diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2b157e346..f7e79e7d4 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -64,13 +64,6 @@ jobs:
         if [[ "${{ runner.os }}" == "Linux" ]] ; then
           export XVFB=xvfb-run
         fi
-        if [[ "${{ github.base_ref }}" == "beta" ]] || [[ "${{ github.ref }}" == "refs/heads/beta" ]] ; then
-          export TESTS_BRANCH=beta
-        else
-          export TESTS_BRANCH=main
-        fi
-        cd build
-        export ASEPRITE=$PWD/bin/aseprite
-        git clone --branch $TESTS_BRANCH --recursive https://github.com/aseprite/tests.git
+        export ASEPRITE=$PWD/build/bin/aseprite
         cd tests
         $XVFB bash run-tests.sh
diff --git a/.gitmodules b/.gitmodules
index 3108b72c0..f053e6d23 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
+[submodule "tests/third_party/json"]
+	path = tests/third_party/json
+	url = https://github.com/aseprite/json.lua
 [submodule "third_party/pixman"]
 	path = third_party/pixman
 	url = https://github.com/aseprite/pixman.git
diff --git a/tests/LICENSE.txt b/tests/LICENSE.txt
new file mode 100644
index 000000000..7d9e58083
--- /dev/null
+++ b/tests/LICENSE.txt
@@ -0,0 +1,21 @@
+Copyright (c) 2018-2022 Igara Studio S.A.
+Copyright (c) 2018 David Capello
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/tests/README.md b/tests/README.md
new file mode 100644
index 000000000..0035a1783
--- /dev/null
+++ b/tests/README.md
@@ -0,0 +1,31 @@
+# Aseprite Tests
+
+Test suite for [Aseprite](https://github.com/aseprite/aseprite)
+to avoid breaking backward compatibility.
+
+This project is cloned by the
+[build.yml](https://github.com/aseprite/aseprite/blob/main/.github/workflows/build.yml) file
+on Aseprite project to do several automated tests:
+
+* Save/load file formats correctly. For this we have `.aseprite`, `.png`,
+  `.gif`, etc. files [sprites](https://github.com/aseprite/tests/tree/main/sprites)
+  folder.
+* Test backward compatibility with [Aseprite CLI](https://www.aseprite.org/docs/cli/) options
+* Future [scripting API](https://github.com/aseprite/api) using [scripts](https://github.com/aseprite/tests/tree/main/scripts)
+
+## How to run tests?
+
+You have to set the `ASEPRITE` environment variable pointing to the
+Aseprite executable and then run `run-tests.sh` from Bash:
+
+    export ASEPRITE=$HOME/your-aseprite-build/bin/aseprite
+    git clone https://github.com/aseprite/tests.git
+    cd tests
+    bash run-tests.sh
+
+You can filter some tests with a regex giving a parameter to
+`run-tests.sh`, for example:
+
+    run-tests.sh color
+
+Should run all tests which have the `color` word in their name.
diff --git a/tests/cli/file-formats.sh b/tests/cli/file-formats.sh
new file mode 100644
index 000000000..cd0b28666
--- /dev/null
+++ b/tests/cli/file-formats.sh
@@ -0,0 +1,61 @@
+#! /bin/bash
+# Copyright (C) 2019  Igara Studio S.A.
+
+# Create a simple image and save it in all formats using scripts
+d=$t/file-formats
+mkdir $d
+cat >$d/gen.lua <<EOF
+local a = Sprite(32, 32)
+app.useTool{ points={{0,0},{31,31}}, tool='filled_ellipse', color=Color(255,255,255) }
+a:saveAs('$d/test.aseprite')
+a:saveAs('$d/test.gif')
+a:saveAs('$d/test.ico')
+a:saveAs('$d/test.jpg')
+a:saveAs('$d/test.pcx')
+a:saveAs('$d/test.svg')
+a:saveAs('$d/test.tga')
+a:saveAs('$d/test.webp')
+EOF
+$ASEPRITE -b -script "$d/gen.lua" || exit 1
+
+# Load image and save in all formats using CLI
+$ASEPRITE -b "$d/test.aseprite" \
+	  -save-as "$d/test2.gif" \
+	  -save-as "$d/test2.ico" \
+	  -save-as "$d/test2.jpg" \
+	  -save-as "$d/test2.pcx" \
+	  -save-as "$d/test2.svg" \
+	  -save-as "$d/test2.tga" \
+	  -save-as "$d/test2.webp" \
+    || exit 1
+
+# Compare that all images are the same/equivalent
+# Note: app.open() and Sprite{fromFile:} are the same
+cat >$d/compare.lua <<EOF
+local a = Sprite{ fromFile="$d/test.aseprite" }
+local b = {
+  app.open("$d/test.gif"), app.open("$d/test2.gif"),
+  app.open("$d/test.ico"), app.open("$d/test2.ico"),
+  app.open("$d/test.jpg"), app.open("$d/test2.jpg"),
+  app.open("$d/test.pcx"), app.open("$d/test2.pcx"),
+  --app.open("$d/test.svg"), -- we don't support loading SVG files
+  app.open("$d/test.tga"), app.open("$d/test2.tga"),
+  app.open("$d/test.webp"), app.open("$d/test2.webp")
+}
+for i,c in ipairs(b) do
+  if c.colorMode == ColorMode.INDEXED then
+    app.activeSprite = c
+    app.command.ChangePixelFormat{ format="rgb" }
+  end
+  assert(c.colorMode == ColorMode.RGB)
+  if c.layers[1].isBackground then   -- jpg and pcx
+    app.activeSprite = c
+    app.command.LayerFromBackground()
+    -- tolerance is 1 to remove jpg noise
+    app.command.ReplaceColor{ from=Color(0, 0, 0, 255), to=Color(0, 0, 0, 0), tolerance=1 }
+    app.command.ReplaceColor{ from=Color(255, 255, 255, 255), to=Color(255, 255, 255, 255), tolerance=1 }
+  end
+  assert(a.cels[1].image:isEqual(c.cels[1].image))
+end
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
diff --git a/tests/cli/help.sh b/tests/cli/help.sh
new file mode 100644
index 000000000..0cedb5f24
--- /dev/null
+++ b/tests/cli/help.sh
@@ -0,0 +1,7 @@
+#! /bin/bash
+# Copyright (C) 2018 Igara Studio S.A.
+
+if ! $ASEPRITE --help | grep "\\-\\-help" > /dev/null ; then
+    echo "FAILED: --help doesn't include usage information"
+    exit 1
+fi
diff --git a/tests/cli/list-layers.sh b/tests/cli/list-layers.sh
new file mode 100644
index 000000000..cd81c1cc9
--- /dev/null
+++ b/tests/cli/list-layers.sh
@@ -0,0 +1,10 @@
+#! /bin/bash
+# Copyright (C) 2018 Igara Studio S.A.
+
+expect "bg
+fg" "$ASEPRITE -b --list-layers sprites/1empty3.aseprite"
+
+expect "a
+b
+c
+d" "$ASEPRITE -b --list-layers sprites/abcd.aseprite"
diff --git a/tests/cli/list-tags.sh b/tests/cli/list-tags.sh
new file mode 100644
index 000000000..0c3c5a2c6
--- /dev/null
+++ b/tests/cli/list-tags.sh
@@ -0,0 +1,5 @@
+#! /bin/bash
+# Copyright (C) 2018 Igara Studio S.A.
+
+expect "a
+b" "$ASEPRITE -b --list-tags sprites/1empty3.aseprite"
diff --git a/tests/cli/save-as.sh b/tests/cli/save-as.sh
new file mode 100644
index 000000000..c8791ed36
--- /dev/null
+++ b/tests/cli/save-as.sh
@@ -0,0 +1,256 @@
+#! /bin/bash
+# Copyright (C) 2018-2021 Igara Studio S.A.
+
+function list_files() {
+    oldwd=$(pwd $PWDARG)
+    cd $1 && ls -1 *.*
+    cd $oldwd
+}
+
+# --save-as
+
+d=$t/save-as
+$ASEPRITE -b sprites/1empty3.aseprite --save-as "$d/image00.png" || exit 1
+expect "image00.png
+image01.png
+image02.png" "list_files $d"
+
+# --ignore-empty --save-as
+
+d=$t/save-as-ignore-empty
+$ASEPRITE -b sprites/1empty3.aseprite --ignore-empty --save-as $d/image00.png || exit 1
+expect "image00.png
+image02.png" "list_files $d"
+
+# --split-layers --save-as
+
+d=$t/save-as-split-layers
+$ASEPRITE -b sprites/1empty3.aseprite --split-layers --save-as $d/layer.png || exit 1
+expect "layer (bg) 0.png
+layer (bg) 1.png
+layer (bg) 2.png
+layer (fg) 0.png
+layer (fg) 1.png
+layer (fg) 2.png" "list_files $d"
+
+# --save-as {layer}
+
+d=$t/save-as-layer
+mkdir $d  # TODO why do we need this?
+$ASEPRITE -b sprites/1empty3.aseprite --save-as $d/layer-{layer}.gif || exit 1
+expect "layer-bg.gif
+layer-fg.gif" "list_files $d"
+
+# --save-as frame8-test.png
+
+d=$t/save-as-frame8-test
+$ASEPRITE -b sprites/1empty3.aseprite --save-as "$d/frame8-test.png" || exit 1
+expect "frame8-test1.png
+frame8-test2.png
+frame8-test3.png" "list_files $d"
+
+# --save-as frame-0.png
+
+d=$t/save-as-frame-0
+$ASEPRITE -b sprites/1empty3.aseprite --save-as "$d/frame-0.png" || exit 1
+expect "frame-0.png
+frame-1.png
+frame-2.png" "list_files $d"
+
+# --save-as frame-00.png
+
+d=$t/save-as-frame-00
+$ASEPRITE -b sprites/1empty3.aseprite --save-as "$d/frame-00.png" || exit 1
+expect "frame-00.png
+frame-01.png
+frame-02.png" "list_files $d"
+
+# --save-as frame-001.png
+
+d=$t/save-as-frame-001
+$ASEPRITE -b sprites/1empty3.aseprite --save-as "$d/frame-001.png" || exit 1
+expect "frame-001.png
+frame-002.png
+frame-003.png" "list_files $d"
+
+# --save-as frame-0032.png
+
+d=$t/save-as-frame-0032
+$ASEPRITE -b sprites/1empty3.aseprite --save-as "$d/frame-0032.png" || exit 1
+expect "frame-0032.png
+frame-0033.png
+frame-0034.png" "list_files $d"
+
+# --trim --save-as
+
+d=$t/save-as-trim
+$ASEPRITE -b --trim sprites/1empty3.aseprite --save-as "$d/trim-000.png" || exit 1
+expect "trim-000.png
+trim-001.png
+trim-002.png" "list_files $d"
+cat >$d/compare.lua <<EOF
+local a = app.open("sprites/1empty3.aseprite")
+assert(a.width == 32)
+assert(a.height == 32)
+app.command.FlattenLayers()
+app.command.AutocropSprite()
+assert(a.width == 22)
+assert(a.height == 26)
+local b = app.open("$d/trim-000.png")
+assert(b.width == 22)
+assert(b.height == 26)
+local cleanImage = Image(b.spec)
+cleanImage:clear()
+for f = 1,3 do
+  local celA = a.layers[1]:cel(f)
+  local celB = b.layers[1]:cel(f)
+  if celA and celB then
+    assert(celA.image:isEqual(celB.image))
+  else
+    assert(not celA)
+    assert(not celB or celB.image:isEqual(cleanImage))
+  end
+end
+EOF
+$ASEPRITE -b --script "$d/compare.lua" || exit 1
+
+# -split-layers -trim -save-as
+
+d=$t/save-as-split-layers-trim
+$ASEPRITE -batch -split-layers -trim sprites/1empty3.aseprite -save-as "$d/{layer}{frame}.png" || exit 1
+expect "bg0.png
+bg1.png
+bg2.png
+fg0.png
+fg1.png
+fg2.png" "list_files $d"
+cat >$d/compare.lua <<EOF
+local orig = app.open("sprites/1empty3.aseprite")
+local bg = app.open("$d/bg0.png")
+local fg = app.open("$d/fg0.png")
+assert(bg.width == 22)
+assert(bg.height == 11)
+assert(fg.width == 19)
+assert(fg.height == 11)
+for f = 1,3 do
+  local origCelBG = orig.layers[1]:cel(f)
+  local origCelFG = orig.layers[2]:cel(f)
+  local celBG = bg.layers[1]:cel(f)
+  local celFG = fg.layers[1]:cel(f)
+  if origCelBG and celBG then
+    assert(origCelBG.image:isEqual(celBG.image))
+  else
+    local cleanImage = Image(celBG.image.spec)
+    cleanImage:clear()
+    assert(not origCelBG)
+    assert(celBG.image:isEqual(cleanImage))
+  end
+  if origCelFG and celFG then
+    assert(origCelFG.image:isEqual(celFG.image))
+  else
+    local cleanImage = Image(celFG.image.spec)
+    cleanImage:clear()
+    assert(not origCelFG)
+    assert(celFG.image:isEqual(cleanImage))
+  end
+end
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# --save-as without path
+# https://github.com/aseprite/aseprite/issues/591
+
+d=$t/save-as-without-path
+mkdir $d
+oldwd=$(pwd $PWDARG)
+cd $d
+$ASEPRITE -b -split-layers $oldwd/sprites/abcd.aseprite -save-as issue591.png || exit 1
+if [[ ! -f "issue591 (a).png" ||
+      ! -f "issue591 (b).png" ||
+      ! -f "issue591 (c).png" ||
+      ! -f "issue591 (d).png" ]]; then
+    echo "FAIL: Regression detected (issue 591)"
+    exit 1
+fi
+cd $oldwd
+
+# --save-as group without showing hidden children
+# https://github.com/aseprite/aseprite/issues/2084#issuecomment-525835889
+
+if [[ "$(uname)" =~ "MINGW" ]] || [[ "$(uname)" =~ "MSYS" ]] ; then
+    # Ignore this test on Windows because we cannot give * as a parameter (?)
+    echo Do nothing
+else
+d=$t/save-as-groups-and-hidden
+mkdir $d
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -save-as "$d/g2-all.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -ignore-layer items -save-as "$d/g2-all-without-items.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -ignore-layer gun -save-as "$d/g2-all-without-gun1.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -ignore-layer sword -save-as "$d/g2-all-without-sword1.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -ignore-layer items/gun -save-as "$d/g2-all-without-gun2.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -ignore-layer items/sword -save-as "$d/g2-all-without-sword2.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer \* -ignore-layer player -save-as "$d/g2-all-without-player.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer player -save-as "$d/g2-player.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer items -save-as "$d/g2-items.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer items/\* -save-as "$d/g2-items-all.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer sword -save-as "$d/g2-sword.png" || exit 1
+$ASEPRITE -b sprites/groups2.aseprite -layer gun -save-as "$d/g2-gun.png" || exit 1
+
+$ASEPRITE -b sprites/groups3abc.aseprite -layer a -save-as "$d/g3-a.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer b -save-as "$d/g3-b.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer c -save-as "$d/g3-c.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer a/\* -save-as "$d/g3-a-all.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer b/\* -save-as "$d/g3-b-all.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer c/\* -save-as "$d/g3-c-all.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer a/a -save-as "$d/g3-aa.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer b/a -save-as "$d/g3-ba.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer c/a -save-as "$d/g3-ca.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer a/b -save-as "$d/g3-ab.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer b/b -save-as "$d/g3-bb.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer c/b -save-as "$d/g3-cb.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer a/c -save-as "$d/g3-ac.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer b/c -save-as "$d/g3-bc.png" || exit 1
+$ASEPRITE -b sprites/groups3abc.aseprite -layer c/c -save-as "$d/g3-cc.png" || exit 1
+
+cat >$d/compare.lua <<EOF
+dofile('scripts/test_utils.lua')
+
+local g2 = app.open("sprites/groups2.aseprite")
+local g3 = app.open("sprites/groups3abc.aseprite")
+
+function img(name)
+  local i = Image{ fromFile="$d/" .. name .. ".png" }
+  if not i then error('file ' .. name .. '.png does not exist') end
+  return i
+end
+
+expect_rendered_layers(img("g2-all"), g2, { "items/gun", "items/sword", "player/head", "player/body" })
+expect_rendered_layers(img("g2-all-without-items"), g2, { "player/head", "player/body" })
+expect_rendered_layers(img("g2-all-without-gun1"), g2, { "items/sword", "player/head", "player/body" })
+expect_rendered_layers(img("g2-all-without-gun2"), g2, { "items/sword", "player/head", "player/body" })
+expect_rendered_layers(img("g2-all-without-sword1"), g2, { "items/gun", "player/head", "player/body" })
+expect_rendered_layers(img("g2-all-without-sword2"), g2, { "items/gun", "player/head", "player/body" })
+expect_rendered_layers(img("g2-player"), g2, { "player/head", "player/body" })
+expect_rendered_layers(img("g2-items"), g2, { "items/sword" })
+expect_rendered_layers(img("g2-items-all"), g2, { "items/gun", "items/sword" })
+expect_rendered_layers(img("g2-sword"), g2, { "items/sword" })
+expect_rendered_layers(img("g2-gun"), g2, { "items/gun" })
+
+expect_rendered_layers(img("g3-a"), g3, { "a/a", "a/b", "a/c" })
+expect_rendered_layers(img("g3-b"), g3, { "b/a", "b/c" })
+expect_rendered_layers(img("g3-c"), g3, { "c/c" })
+expect_rendered_layers(img("g3-a-all"), g3, { "a/a", "a/b", "a/c" })
+expect_rendered_layers(img("g3-b-all"), g3, { "b/a", "b/b", "b/c" })
+expect_rendered_layers(img("g3-c-all"), g3, { "c/a", "c/b", "c/c" })
+expect_rendered_layers(img("g3-aa"), g3, { "a/a" })
+expect_rendered_layers(img("g3-ab"), g3, { "a/b" })
+expect_rendered_layers(img("g3-ac"), g3, { "a/c" })
+expect_rendered_layers(img("g3-ba"), g3, { "b/a" })
+expect_rendered_layers(img("g3-bb"), g3, { "b/b" })
+expect_rendered_layers(img("g3-bc"), g3, { "b/c" })
+expect_rendered_layers(img("g3-ca"), g3, { "c/a" })
+expect_rendered_layers(img("g3-cb"), g3, { "c/b" })
+expect_rendered_layers(img("g3-cc"), g3, { "c/c" })
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+fi
diff --git a/tests/cli/sheet.sh b/tests/cli/sheet.sh
new file mode 100644
index 000000000..27c46b4aa
--- /dev/null
+++ b/tests/cli/sheet.sh
@@ -0,0 +1,402 @@
+#! /bin/bash
+# Copyright (C) 2019-2022 Igara Studio S.A.
+
+# $1 = first sprite sheet json file
+# $2 = second sprite sheet json file
+function compare_sheet_data() {
+    cat $1 | grep -v "\"image\"" > $1-tmp
+    cat $2 | grep -v "\"image\"" > $2-tmp
+    diff -u $1-tmp $2-tmp
+}
+
+# --sheet and STDOUT
+
+d=$t/sheet
+mkdir $d # we need to create the directory because the >STDOUT redirection
+if ! $ASEPRITE -b sprites/1empty3.aseprite --sheet "$d/sheet.png" > "$d/stdout.json" ; then
+   exit 1
+fi
+cat >$d/compare.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local data = json.decode(io.open('$d/stdout.json'):read('a'))
+local frames = { data.frames['1empty3 0.aseprite'],
+                 data.frames['1empty3 1.aseprite'],
+                 data.frames['1empty3 2.aseprite'] }
+assert(frames[1].frame.x == 0)
+assert(frames[2].frame.x == 32)
+assert(frames[3].frame.x == 64)
+for i,v in ipairs(frames) do
+  assert(v.frame.y == 0)
+  assert(v.frame.w == 32)
+  assert(v.frame.h == 32)
+end
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# --sheet --data
+
+d0=$d
+d=$t/sheet-data
+$ASEPRITE -b sprites/1empty3.aseprite --sheet "$d/sheet.png" --data "$d/sheet.json" || exit 1
+compare_sheet_data $d0/stdout.json $d/sheet.json || exit 1
+cat >$d/compare.lua <<EOF
+local orig = app.open("sprites/1empty3.aseprite")
+local sheet = app.open("$d/sheet.png")
+local expected = Image(orig.width*3, orig.height, orig.colorMode)
+expected:clear()
+for f = 1,3 do
+  expected:drawSprite(orig, f, (f-1)*orig.width, 0)
+end
+assert(expected:isEqual(sheet.cels[1].image))
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# vertical sprite sheet
+
+d=$t/vertical-sheet
+mkdir $d
+# TODO this should be possible in a future
+# $ASEPRITE -b sprites/1empty3.aseprite -sheet-type vertical --sheet "$d/sheet.png" --data "$d/sheet.json" || exit 1
+cat >$d/create.lua <<EOF
+local sprite = app.open("sprites/1empty3.aseprite")
+app.command.ExportSpriteSheet {
+  type="vertical",
+  textureFilename="$d/sheet1.png",
+  dataFilename="$d/sheet1.json"
+}
+app.command.ExportSpriteSheet {
+  type=SpriteSheetType.VERTICAL,
+  textureFilename="$d/sheet2.png",
+  dataFilename="$d/sheet2.json"
+}
+EOF
+$ASEPRITE -b -script "$d/create.lua" || exit 1
+compare_sheet_data "$d/sheet1.json" "$d/sheet2.json" || exit 1
+cmp "$d/sheet1.png" "$d/sheet2.png" || exit 1
+cat >$d/compare.lua <<EOF
+local orig = app.open("sprites/1empty3.aseprite")
+local sheet = app.open("$d/sheet1.png")
+local expected = Image(orig.width, orig.height*3, orig.colorMode)
+expected:clear()
+for f = 1,3 do
+  expected:drawSprite(orig, f, 0, (f-1)*orig.height)
+end
+assert(expected:isEqual(sheet.cels[1].image))
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# --split-layers --sheet --data
+
+d=$t/split-layers-sheet-data
+$ASEPRITE -b --split-layers sprites/1empty3.aseprite \
+	  --filename-format "{layer}-{frame}" \
+	  --sheet "$d/sheet.png" \
+	  --data "$d/sheet.json" || exit 1
+cat >$d/compare.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local data = json.decode(io.open('$d/sheet.json'):read('a'))
+assert(data.meta.size.w == 96)
+assert(data.meta.size.h == 64)
+
+local orig = app.open("sprites/1empty3.aseprite")
+local sheet = app.open("$d/sheet.png")
+local expected = Image(orig.width*3, orig.height*2, orig.colorMode)
+expected:clear()
+for lay = 1,2 do
+  orig.layers[1].isVisible = (lay == 1)
+  orig.layers[2].isVisible = (lay == 2)
+  for frm = 1,3 do
+    local x, y = (frm-1)*orig.width, (lay-1)*orig.height
+    expected:drawSprite(orig, frm, x, y)
+
+    local frmData = data.frames[orig.layers[lay].name .. '-' .. (frm-1)]
+    assert(frmData.frame.x == x)
+    assert(frmData.frame.y == y)
+    assert(frmData.frame.w == 32)
+    assert(frmData.frame.h == 32)
+  end
+end
+assert(expected:isEqual(sheet.cels[1].image))
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# Test that the transparent color persists in the output sheet
+
+d=$t/sheet-custom-transparent-index
+if ! $ASEPRITE -b sprites/bg-index-3.aseprite -sheet "$d/sheet.aseprite" -data "$d/sheet.json" ; then
+    exit 1
+fi
+cat >$d/compare.lua <<EOF
+local original = Sprite{ fromFile='sprites/bg-index-3.aseprite' }
+assert(original.transparentColor == 3)
+local sheet = Sprite{ fromFile='$d/sheet.aseprite' }
+assert(sheet.transparentColor == 3)
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# Don't discard empty frames if -ignore-empty is not used (even if -trim is used)
+# https://github.com/aseprite/aseprite/issues/2116
+# -layer -trim -ignore-empty -list-tags -sheet -data
+
+d=$t/sheet-trim-without-ignore-empty
+$ASEPRITE -b \
+	  -list-tags \
+	  -layer "c" \
+	  "sprites/tags3.aseprite" \
+	  -trim \
+	  -sheet-pack \
+	  -sheet "$d/sheet1.png" \
+	  -format json-array \
+	  -data "$d/sheet1.json" || exit 1
+$ASEPRITE -b \
+	  -list-tags \
+	  -layer "c" \
+	  "sprites/tags3.aseprite" \
+	  -trim -ignore-empty \
+	  -sheet-pack \
+	  -sheet "$d/sheet2.png" \
+	  -format json-array \
+	  -data "$d/sheet2.json" || exit 1
+
+cat >$d/check.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local sheet1 = json.decode(io.open('$d/sheet1.json'):read('a'))
+local sheet2 = json.decode(io.open('$d/sheet2.json'):read('a'))
+assert(#sheet1.frames == 12)
+assert(#sheet2.frames == 4)
+EOF
+$ASEPRITE -b -script "$d/check.lua" || exit 1
+
+# -sheet -sheet-columns vs -sheet-rows
+
+d=$t/sheet-columns-and-rows
+$ASEPRITE -b -split-layers sprites/1empty3.aseprite \
+	  -filename-format "{layer}{frame}" \
+	  -sheet "$d/sheet1.png" \
+	  -sheet-type rows \
+	  -sheet-columns 3 \
+	  -data "$d/sheet1.json" || exit $?
+$ASEPRITE -b -split-layers sprites/1empty3.aseprite \
+	  -filename-format "{layer}{frame}" \
+	  -sheet "$d/sheet2.png" \
+	  -sheet-type columns \
+	  -sheet-rows 3 \
+	  -data "$d/sheet2.json" || exit $?
+$ASEPRITE -b \
+	  -script-param file1=$d/sheet1.json \
+	  -script-param file2=$d/sheet2.json \
+	  -script scripts/compare_sprite_sheets.lua || exit $?
+
+# -sheet -trim vs -trim-sprite
+
+d=$t/sheet-columns-and-rows
+$ASEPRITE -b -split-layers sprites/1empty3.aseprite \
+	  -trim \
+	  -filename-format "{layer}{frame}" \
+	  -sheet "$d/sheet1.png" \
+	  -data "$d/sheet1.json" || exit $?
+
+$ASEPRITE -b -split-layers sprites/1empty3.aseprite \
+	  -trim-sprite \
+	  -filename-format "{layer}{frame}" \
+	  -sheet "$d/sheet2.png" \
+	  -data "$d/sheet2.json" || exit $?
+$ASEPRITE -b \
+	  -script-param file1=$d/sheet1.json \
+	  -script-param file2=$d/sheet2.json \
+	  -script scripts/compare_sprite_sheets.lua || exit $?
+
+# Test all sprite sheet types
+# -sheet horizontal/vertical/rows/columns/packed
+d=$t/sheet-all-types
+for type in horizontal vertical rows columns packed ; do
+    $ASEPRITE -b "sprites/tags3.aseprite" \
+	      -sheet-type $type -sheet "$d/$type.png" \
+	      -format json-array -data "$d/$type.json" || exit $?
+
+    $ASEPRITE -b -split-layers "sprites/tags3.aseprite" \
+	      -sheet-type $type -sheet "$d/$type-layers.png" \
+	      -format json-array -data "$d/$type-layers.json" || exit $?
+
+    $ASEPRITE -b -split-layers -merge-duplicates "sprites/tags3.aseprite" \
+	      -sheet-type $type -sheet "$d/$type-layers-merge-duplicates.png" \
+	      -format json-array -data "$d/$type-layers-merge-duplicates.json" || exit $?
+
+    $ASEPRITE -b -split-tags "sprites/tags3.aseprite" \
+	      -sheet-type $type -sheet "$d/$type-tags.png" \
+	      -format json-array -data "$d/$type-tags.json" || exit $?
+
+    $ASEPRITE -b -split-tags -trim "sprites/tags3.aseprite" \
+	      -sheet-type $type -sheet "$d/$type-tags-trim.png" \
+	      -format json-array -data "$d/$type-tags-trim.json" || exit $?
+
+    $ASEPRITE -b -split-layers -split-tags "sprites/tags3.aseprite" \
+	      -sheet-type $type -sheet "$d/$type-layer-tags.png" \
+	      -format json-array -data "$d/$type-layer-tags.json" || exit $?
+done
+
+for type in horizontal vertical rows columns ; do
+    for subtype in "" "-layers" "-layers-merge-duplicates" "-tags" "-tags-trim" "-layer-tags" ; do
+	$ASEPRITE -b \
+		  -script-param file1=$d/packed$subtype.json \
+		  -script-param file2=$d/$type$subtype.json \
+		  -script scripts/compare_sprite_sheets.lua || exit $?
+    done
+done
+
+# "Trim Cels" (-trim) with -merge-duplicates didn't generate the
+# correct "spriteSourceSize" for each frame.
+# https://igarastudio.zendesk.com/agent/tickets/407
+d=$t/ticket-407
+for layer in a b ; do
+    $ASEPRITE -b -layer "$layer" "sprites/point4frames.aseprite" \
+	      -trim \
+	      -data "$d/data1-$layer.json" \
+	      -format json-array -sheet "$d/sheet1-$layer.png" || exit 1
+    $ASEPRITE -b -layer "$layer" "sprites/point4frames.aseprite" \
+	      -trim -merge-duplicates \
+	      -data "$d/data2-$layer.json" \
+	      -format json-array -sheet "$d/sheet2-$layer.png" || exit 1
+    cat >$d/compare.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local data1 = json.decode(io.open('$d/data1-$layer.json'):read('a'))
+local data2 = json.decode(io.open('$d/data2-$layer.json'):read('a'))
+assert(#data1.frames == #data2.frames)
+for i = 1,#data1.frames do
+    local a = data1.frames[i].spriteSourceSize
+    local b = data2.frames[i].spriteSourceSize
+    assert(a.x == b.x)
+    assert(a.y == b.y)
+    assert(a.w == b.w)
+    assert(a.h == b.h)
+end
+EOF
+    $ASEPRITE -b -script "$d/compare.lua" || exit 1
+done
+
+# Same problem as in ticket 407 but with "sourceSize" field and
+# different sprites in the same texture atlas.
+d=$t/ticket-407-w-atlas
+$ASEPRITE -b \
+	  -layer a "sprites/point4frames.aseprite" \
+	  "sprites/point2frames.aseprite" \
+	  -data "$d/data1.json" \
+	  -format json-array -sheet "$d/sheet1.png" || exit 1
+$ASEPRITE -b \
+	  -layer a "sprites/point4frames.aseprite" \
+	  "sprites/point2frames.aseprite" \
+	  -trim \
+	  -data "$d/data2.json" \
+	  -format json-array -sheet-pack -sheet "$d/sheet2.png" || exit 1
+cat >$d/compare.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local data1 = json.decode(io.open('$d/data1.json'):read('a'))
+local data2 = json.decode(io.open('$d/data2.json'):read('a'))
+assert(#data1.frames == #data2.frames)
+for i = 1,#data1.frames do
+    local a = data1.frames[i].sourceSize
+    local b = data2.frames[i].sourceSize
+    assert(a.w == b.w)
+    assert(a.h == b.h)
+end
+EOF
+$ASEPRITE -b -script "$d/compare.lua" || exit 1
+
+# https://github.com/aseprite/aseprite/issues/2380
+# Check that -split-layers and -list-layers include group information
+d=$t/issue-2380
+$ASEPRITE -b -trim -all-layers "sprites/groups3abc.aseprite" -data "$d/sheet1.json" -format json-array -sheet "$d/sheet1.png" -list-layers
+$ASEPRITE -b -trim -all-layers -split-layers "sprites/groups3abc.aseprite" -data "$d/sheet2.json" -format json-array -sheet "$d/sheet2.png" -list-layers
+cat >$d/check.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local sheet1 = json.decode(io.open('$d/sheet1.json'):read('a'))
+local sheet2 = json.decode(io.open('$d/sheet2.json'):read('a'))
+assert(#sheet1.meta.layers == 12)
+assert(#sheet2.meta.layers == 12)
+assert(json.encode(sheet1.meta.layers) == json.encode(sheet2.meta.layers))
+EOF
+$ASEPRITE -b -script "$d/check.lua" || exit 1
+
+# https://github.com/aseprite/aseprite/issues/2432
+# -ignore-layer is ignoring extra layers when -split-layers is used
+d=$t/issue-2432
+$ASEPRITE -b -trim -ignore-layer "c" -all-layers "sprites/groups3abc.aseprite" -data "$d/sheet1.json" -format json-array -sheet "$d/sheet1.png" -list-layers
+$ASEPRITE -b -trim -ignore-layer "c" -all-layers -split-layers "sprites/groups3abc.aseprite" -data "$d/sheet2.json" -format json-array -sheet "$d/sheet2.png" -list-layers
+cat >$d/check.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local sheet1 = json.decode(io.open('$d/sheet1.json'):read('a'))
+local sheet2 = json.decode(io.open('$d/sheet2.json'):read('a'))
+assert(#sheet1.meta.layers == 8)
+assert(#sheet2.meta.layers == 8)
+assert(json.encode(sheet1.meta.layers) == json.encode(sheet2.meta.layers))
+EOF
+$ASEPRITE -b -script "$d/check.lua" || exit 1
+
+# https://github.com/aseprite/aseprite/issues/2600
+# -merge-duplicates -split-layers -trim give incorrect 'frame' coordinates on linked cels
+d=$t/issue-2600
+$ASEPRITE -b -list-layers -format json-array -trim -merge-duplicates -split-layers -all-layers "sprites/link.aseprite" -data "$d/sheet.json" -sheet "$d/sheet.png"
+cat >$d/check.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local sheet = json.decode(io.open('$d/sheet.json'):read('a'))
+local restoredSprite = Sprite(sheet.frames[1].sourceSize.w, sheet.frames[1].sourceSize.h, ColorMode.RGB)
+local spriteSheet = Image{ fromFile="$d/sheet.png" }
+local lay = 1
+repeat
+  local layerName = sheet.meta.layers[lay].name
+  local layer = restoredSprite.layers[lay]
+  for i=1, #sheet.frames do
+    if string.find(sheet.frames[i].filename, layerName) ~= nil then
+      local sample = sheet.frames[i]
+      local dotAseIndex = string.find(sample.filename, ".ase")
+      local frame = (string.sub(sample.filename, dotAseIndex - 2, dotAseIndex - 1)) + 1
+      for f=#restoredSprite.frames, frame-1 do
+        restoredSprite:newEmptyFrame()
+      end
+      local image = Image(sample.frame.w, sample.frame.h)
+      for y=0,image.height-1 do
+        for x=0,image.width-1 do
+          image:drawPixel(x, y, spriteSheet:getPixel(sample.frame.x + x, sample.frame.y + y))
+        end
+      end
+      restoredSprite:newCel(layer, frame, image, Point(sample.spriteSourceSize.x, sample.spriteSourceSize.y))
+    end
+  end
+  if lay < #sheet.meta.layers then
+    restoredSprite:newLayer()
+  end
+  lay = lay + 1
+until(lay > #sheet.meta.layers)
+
+app.activeSprite = restoredSprite
+app.activeLayer = restoredSprite.layers[#restoredSprite.layers]
+for i=1,#restoredSprite.layers-1 do
+  app.command.MergeDownLayer()
+end
+
+local orig = app.open("sprites/link.aseprite")
+app.activeSprite = orig
+app.activeLayer = orig.layers[#orig.layers]
+for i=1,#orig.layers-1 do
+  app.command.MergeDownLayer()
+end
+
+assert(orig.width == restoredSprite.width)
+assert(orig.height == restoredSprite.height)
+assert(#orig.frames == #restoredSprite.frames)
+for fr=1,#restoredSprite.frames do
+  for celIndex1=1,#restoredSprite.cels do
+    if restoredSprite.cels[celIndex1].frameNumber == fr then
+      for celIndex2=1,#orig.cels do
+        if orig.cels[celIndex2].frameNumber == fr then
+          assert(orig.cels[celIndex2].position == restoredSprite.cels[celIndex1].position)
+          if orig.cels[celIndex2].image ~= nil and restoredSprite.cels[celIndex1].image ~= nil then
+            assert(orig.cels[celIndex2].image:isEqual(restoredSprite.cels[celIndex1].image))
+          end
+        end
+      end
+    end
+  end
+end
+EOF
+$ASEPRITE -b -script "$d/check.lua" || exit 1
diff --git a/tests/cli/version.sh b/tests/cli/version.sh
new file mode 100644
index 000000000..4e64cd7a0
--- /dev/null
+++ b/tests/cli/version.sh
@@ -0,0 +1,7 @@
+#! /bin/bash
+# Copyright (C) 2018 Igara Studio S.A.
+
+if ! $ASEPRITE --version | grep "Aseprite 1\\." > /dev/null ; then
+    echo "FAILED: --version doesn't include 'Aseprite 1.' string"
+    exit 1
+fi
diff --git a/tests/run-tests.sh b/tests/run-tests.sh
new file mode 100755
index 000000000..f94e90136
--- /dev/null
+++ b/tests/run-tests.sh
@@ -0,0 +1,107 @@
+#! /bin/bash
+# Copyright (C) 2018 Igara Studio S.A.
+# Copyright (C) 2018 David Capello
+
+if [[ "$ASEPRITE" == "" ]]; then
+    echo ASEPRITE env var must be pointing to the Aseprite executable
+    exit 1
+fi
+
+function fail() {
+    echo FAIL
+    echo $BASH_SOURCE:$BASH_LINENO: error: $*
+    exit 1
+}
+
+function expect() {
+    if [[ $1 != "$($2 | tr -d "\r")" ]] ; then
+	echo "FAILED: $2"
+	echo "EXPECTED: $1"
+	echo "RESULT: $($2)"
+	exit 1
+    fi
+}
+
+# General information
+echo ----------------------------------------------------------------------
+echo $ASEPRITE --version
+$ASEPRITE --version
+
+filter="$*"
+if [[ "$filter" != "" ]]; then
+    echo Filter: $filter
+fi
+
+t=$(mktemp -d)
+if [[ "$(uname)" =~ "MINGW" ]] || [[ "$(uname)" =~ "MSYS" ]] ; then
+    PWDARG=-W
+    t=$(cd "$t" && pwd $PWDARG)
+else
+    PWDARG=
+fi
+echo Temp dir: $t
+export ASEPRITE_USER_FOLDER=$t
+
+if [[ "$filter" == "" ]] || [[ "console" =~ $filter ]]; then
+    echo ----------------------------------------------------------------------
+    echo "Testing console..."
+    echo "uname=$(uname)"
+
+    $ASEPRITE -b --script scripts/console_assert.lua >$t/tmp 2>&1
+    ! grep -q "this should be in the output" $t/tmp && fail "print() text not found in output"
+    ! grep -q "assertion failed" $t/tmp && fail "assert() text not found in output"
+    grep -q "this should not be in the output" $t/tmp && fail "text that shouldn't be in the output is"
+
+    if [[ "$(uname)" =~ "MINGW" ]] || [[ "$(uname)" =~ "MSYS" ]] ; then
+	echo Ignore console tests on Windows
+    else
+	$ASEPRITE -b --script scripts/console_print.lua >$t/tmp 2>&1
+	cat >$t/tmp_expected <<EOF
+hello world
+1	2	3
+EOF
+	! diff -u $t/tmp $t/tmp_expected && fail
+    fi
+fi
+
+first=0
+result=0
+for script in scripts/*.lua ; do
+    [[ $script =~ console ]] && continue
+    if [[ "$filter" != "" ]]; then
+	[[ $script =~ $filter ]] || continue
+    fi
+    if [ $first == 0 ]; then
+	echo ----------------------------------------------------------------------
+	echo "Testing scripts..."
+	first=1
+    fi
+    echo "Running $script"
+    if ! $ASEPRITE -b --script $script >$t/tmp 2>&1 ; then
+	echo FAILED && cat $t/tmp
+	result=1
+    fi
+done
+
+first=0
+for script in cli/*.sh ; do
+    if [[ "$filter" == "" ]] || [[ $script =~ $filter ]]; then
+	if [ $first == 0 ]; then
+	    echo ----------------------------------------------------------------------
+	    echo "Testing CLI..."
+	    first=1
+	fi
+	echo "Running $script"
+	source $script
+    fi
+done
+
+echo ----------------------------------------------------------------------
+if [ $result == 0 ] ; then
+    echo Done
+else
+    echo FAILED
+fi
+echo ----------------------------------------------------------------------
+
+exit $result
diff --git a/tests/scripts/app_active.lua b/tests/scripts/app_active.lua
new file mode 100644
index 000000000..c01eb15d9
--- /dev/null
+++ b/tests/scripts/app_active.lua
@@ -0,0 +1,25 @@
+-- Copyright (C) 2018-2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local s = Sprite(32, 64)
+assert(s == app.activeSprite)
+assert(s == app.site.sprite)
+assert(s == app.activeFrame.sprite)
+assert(s == app.site.frame.sprite)
+assert(1 == app.activeFrame.frameNumber)
+assert(1 == app.site.frame.frameNumber)
+assert(1 == app.site.frameNumber)
+assert(0.100 == app.activeFrame.duration) -- Default frame duration
+assert(0.100 == app.site.frame.duration)
+assert(s == app.activeLayer.sprite)
+assert(s == app.site.layer.sprite)
+assert(s == app.activeCel.sprite)
+assert(s == app.site.cel.sprite)
+
+app.activeFrame.duration = 0.8
+
+app.command.NewFrame()
+assert(2 == app.activeFrame.frameNumber)
+assert(0.8 == app.activeFrame.duration) -- Copy frame duration of previous frame
diff --git a/tests/scripts/app_command.lua b/tests/scripts/app_command.lua
new file mode 100644
index 000000000..42d66c89c
--- /dev/null
+++ b/tests/scripts/app_command.lua
@@ -0,0 +1,606 @@
+-- Copyright (C) 2019-2020  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+local rgba = app.pixelColor.rgba
+local rgbaR = app.pixelColor.rgbaR
+local rgbaG = app.pixelColor.rgbaG
+local rgbaB = app.pixelColor.rgbaB
+
+do -- Undo/Redo commands (like app.undo/redo())
+  local s = Sprite(32, 32)
+  assert(s.width == 32)
+  assert(s.height == 32)
+
+  s:resize(50, 40)
+  assert(s.width == 50)
+  assert(s.height == 40)
+
+  app.command.Undo()
+  assert(s.width == 32)
+  assert(s.height == 32)
+
+  app.command.Redo()
+  assert(s.width == 50)
+  assert(s.height == 40)
+end
+
+do -- NewSprite
+  local s1 = app.activeSprite
+  app.command.NewFile{ }
+  assert(s1 == app.activeSprite)
+  app.command.NewFile{ width=256, height=128, colorMode=ColorMode.INDEXED }
+  local s2 = app.activeSprite
+  assert(s1 ~= s2)
+  assert(s2.width == 256)
+  assert(s2.height == 128)
+  assert(s2.colorMode == ColorMode.INDEXED)
+end
+
+do -- ExportSpriteSheet
+  local s = Sprite{ fromFile="sprites/2f-index-3x3.aseprite" }
+  app.command.ExportSpriteSheet {
+    type="horizontal",
+    textureFilename="_test_export_spritesheet1.png",
+    shapePadding=1
+  }
+  local i = Image{ fromFile="_test_export_spritesheet1.png" }
+  expect_img(i,  {
+    11,8,11,21,8,11,11,
+    11,8,11,21,11,8,11,
+    11,8,11,21,11,11,8,
+  })
+end
+
+do -- NewLayer/RemoveLayer
+  local s = Sprite(32, 32)
+  assert(#s.layers == 1)
+  local lay = s.layers[1]
+  app.command.NewLayer{top=true}
+  local lay2 = app.activeLayer
+  assert(#s.layers == 2)
+  assert(s.layers[2].isImage)
+
+  app.command.NewLayer{top=true, group=true}
+  local lay3 = app.activeLayer
+  assert(#s.layers == 3)
+  assert(s.layers[3].isGroup)
+
+  assert(app.activeLayer == lay3)
+  app.command.RemoveLayer()
+  assert(app.activeLayer == lay2)
+  assert(#s.layers == 2)
+
+  app.command.RemoveLayer()
+  assert(app.activeLayer == lay)
+  assert(#s.layers == 1)
+end
+
+do -- Background/Transparent layers
+  local s = Sprite(32, 32)
+  assert(s.layers[1].isTransparent)
+  assert(s.cels[1].image:getPixel(0, 0) == app.pixelColor.rgba(0, 0, 0, 0))
+
+  app.bgColor = Color(32, 64, 128)
+  app.command.BackgroundFromLayer() -- the layer will be filled with app.bgColor
+  assert(s.layers[1].isBackground)
+  assert(s.layers[1] == s.backgroundLayer)
+  assert(s.cels[1].image:getPixel(0, 0) == app.pixelColor.rgba(32, 64, 128, 255))
+
+  app.command.LayerFromBackground()
+  assert(s.layers[1].isTransparent)
+  assert(s.cels[1].image:getPixel(0, 0) == app.pixelColor.rgba(32, 64, 128, 255))
+end
+
+do -- Crop and Trim
+  local s = Sprite(32, 32)
+  s.selection:select(4, 5, 8, 10)
+  assert(s.cels[1].bounds == Rectangle(0, 0, 32, 32))
+
+  -- Crop
+
+  app.command.CropSprite()
+  assert(s.width == 8)
+  assert(s.height == 10)
+  assert(s.cels[1].bounds == Rectangle(-4, -5, 32, 32))
+
+  -- Autocrop (Trim)
+
+  app.command.AutocropSprite() -- Trim does nothing when we should remove all pixels
+  assert(s.width == 8)
+  assert(s.height == 10)
+
+  s.cels[1].image:putPixel(5, 5, Color(255, 0, 0))
+  s.cels[1].image:putPixel(4, 6, Color(255, 0, 0))
+  app.command.AutocropSprite()
+  assert(s.width == 2)
+  assert(s.height == 2)
+end
+
+do -- Cel Opacity
+  local s = Sprite(32, 32)
+  local c = s.cels[1]
+  assert(c.opacity == 255)
+
+  app.command.CelOpacity{opacity=128}
+  assert(c.opacity == 128)
+
+  s.cels[1].opacity = 255
+  assert(c.opacity == 255)
+
+  app.undo()
+  assert(c.opacity == 128)
+  app.undo()
+  assert(c.opacity == 255)
+end
+
+do -- PaletteSize
+  local s = Sprite(32, 32)
+  assert(#s.palettes[1] == 256)
+  app.command.PaletteSize{ size=32 }
+  assert(#s.palettes[1] == 32)
+  app.command.PaletteSize{ size=8 }
+  assert(#s.palettes[1] == 8)
+end
+
+do -- CanvasSize
+  local s = Sprite(32, 32)
+  assert(s.bounds == Rectangle(0, 0, 32, 32))
+  app.command.CanvasSize{ left=2 }
+  assert(s.bounds == Rectangle(0, 0, 34, 32))
+  app.command.CanvasSize{ top=2, right=4, bottom=8 }
+  assert(s.bounds == Rectangle(0, 0, 38, 42))
+end
+
+do -- ReplaceColor
+  local s = Sprite(4, 4)
+  local cel = app.activeCel
+  local red = Color(255, 0, 0)
+  local yellow = Color(255, 255, 0)
+  local blue = Color(0, 0, 255)
+  local r = red.rgbaPixel
+  local y = yellow.rgbaPixel
+  local b = blue.rgbaPixel
+
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { 0, 0, 0, 0,
+               0, 0, 0, 0,
+               0, 0, 0, 0,
+               0, 0, 0, 0 })
+
+  app.useTool{ brush=Brush(1), color=red, points={Point(1,1)} }
+  app.useTool{ brush=Brush(1), color=yellow, points={Point(2,2)} }
+  expect_eq(cel.bounds, Rectangle(1, 1, 2, 2))
+  expect_img(cel.image,
+             { r, 0,
+               0, y })
+
+  app.command.ReplaceColor{ from=red, to=blue }
+  expect_eq(cel.bounds, Rectangle(1, 1, 2, 2))
+  expect_img(cel.image,
+             { b, 0,
+               0, y })
+end
+
+do -- Invert
+  local s = Sprite(2, 2)
+  local cel = app.activeCel
+  local aa = Color(255, 128, 128).rgbaPixel
+  local na = Color(0, 127, 127).rgbaPixel
+  local bb = Color(128, 128, 255).rgbaPixel
+  local nb = Color(127, 127, 0).rgbaPixel
+  local i = cel.image
+
+  i:drawPixel(0, 0, aa)
+  i:drawPixel(1, 0, bb)
+  i:drawPixel(0, 1, bb)
+  i:drawPixel(1, 1, aa)
+  expect_img(cel.image,
+             { aa, bb,
+               bb, aa })
+
+  app.command.InvertColor()
+  expect_img(cel.image,
+             { na, nb,
+               nb, na })
+
+  local Na = Color(0, 127, 128).rgbaPixel
+  local Ng = Color(127, 127, 255).rgbaPixel
+  app.command.InvertColor{ channels=FilterChannels.BLUE }
+  expect_img(cel.image,
+             { Na, Ng,
+               Ng, Na })
+end
+
+do -- Outline
+  local s = Sprite(4, 4)
+  local cel = app.activeCel
+  local red = Color(255, 0, 0)
+  local yellow = Color(255, 255, 0)
+  local blue = Color(0, 0, 255)
+  local r = red.rgbaPixel
+  local y = yellow.rgbaPixel
+  local b = blue.rgbaPixel
+
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { 0, 0, 0, 0,
+               0, 0, 0, 0,
+               0, 0, 0, 0,
+               0, 0, 0, 0 })
+
+  app.useTool{ brush=Brush(1), color=red, points={Point(1,1)} }
+  app.useTool{ brush=Brush(1), color=yellow, points={Point(2,2)} }
+  expect_eq(cel.bounds, Rectangle(1, 1, 2, 2))
+  expect_img(cel.image,
+             { r, 0,
+               0, y })
+
+  app.command.Outline{ color=blue }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { 0, b, 0, 0,
+               b, r, b, 0,
+               0, b, y, b,
+               0, 0, b, 0 })
+
+  -- Test "bgColor", "matrix", "place" params
+
+  app.useTool{ tool='filled_rectangle', brush=Brush(1), color=blue, points={Point(0,0), Point(3,3)} }
+  app.useTool{ tool='filled_rectangle', brush=Brush(1), color=yellow, points={Point(1,1), Point(2,2)} }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { b, b, b, b,
+               b, y, y, b,
+               b, y, y, b,
+               b, b, b, b })
+
+  app.command.Outline{ color=red, bgColor=blue, matrix='circle' }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { b, r, r, b,
+               r, y, y, r,
+               r, y, y, r,
+               b, r, r, b })
+  app.undo()
+
+  app.command.Outline{ color=red, bgColor=blue, matrix='square' }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { r, r, r, r,
+               r, y, y, r,
+               r, y, y, r,
+               r, r, r, r })
+  app.undo()
+
+  app.command.Outline{ color=red, bgColor=blue, place='inside' }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(cel.image,
+             { b, b, b, b,
+               b, r, r, b,
+               b, r, r, b,
+               b, b, b, b })
+
+end
+
+do -- BrightnessContrast
+  local s = Sprite(2, 2)
+  local cel = app.activeCel
+  local c = { rgba(255, 128, 64), rgba(250, 225, 110),
+              rgba( 30,  60,  0), rgba(200, 100,  50), }
+  local i = cel.image
+
+  i:drawPixel(0, 0, c[1])
+  i:drawPixel(1, 0, c[2])
+  i:drawPixel(0, 1, c[3])
+  i:drawPixel(1, 1, c[4])
+  expect_img(i,
+             { c[1], c[2],
+               c[3], c[4] })
+
+  app.command.BrightnessContrast() -- Do nothing by default
+  expect_img(i,
+             { c[1], c[2],
+               c[3], c[4] })
+
+  local d = {}
+  for k,v in ipairs(c) do
+    d[k] = rgba(math.min(255, rgbaR(v)*1.5),
+                math.min(255, rgbaG(v)*1.5),
+                math.min(255, rgbaB(v)*1.5), 255)
+  end
+  app.command.BrightnessContrast{ brightness=50 } -- Do nothing by default
+  expect_img(i,
+             { d[1], d[2],
+               d[3], d[4] })
+end
+
+do -- Despeckle
+  local s = Sprite(5, 5)
+  local white = Color(255, 255, 255)
+  local red = Color(255, 0, 0)
+
+  app.bgColor = white
+  app.command.BackgroundFromLayer()
+
+  local cel = app.activeCel
+  local i = cel.image
+  local b = white.rgbaPixel
+  local c = red.rgbaPixel
+  expect_img(i,
+             { b,b,b,b,b,
+               b,b,b,b,b,
+               b,b,b,b,b,
+               b,b,b,b,b,
+               b,b,b,b,b })
+
+  app.useTool{ tool='filled_rectangle', brush=Brush(1), color=red,
+               points={Point(1,1),Point(3,3)} }
+  expect_img(i,
+             { b,b,b,b,b,
+               b,c,c,c,b,
+               b,c,c,c,b,
+               b,c,c,c,b,
+               b,b,b,b,b })
+
+  app.command.Despeckle()
+  expect_img(i,
+             { b,b,b,b,b,
+               b,b,c,b,b,
+               b,c,c,c,b,
+               b,b,c,b,b,
+               b,b,b,b,b })
+
+  app.command.Despeckle()
+  expect_img(i,
+             { b,b,b,b,b,
+               b,b,b,b,b,
+               b,b,c,b,b,
+               b,b,b,b,b,
+               b,b,b,b,b })
+end
+
+do -- HueSaturation
+  local s = Sprite(1, 1)
+  local cel = app.activeCel
+  local i = cel.image
+  local b = Color(255, 0, 0).rgbaPixel
+
+  i:drawPixel(0, 0, b)
+  expect_img(i, { b })
+
+  app.command.HueSaturation{ hue=360 } -- Do nothing (change hue to a full 360 circle)
+  expect_img(i, { b })
+
+  app.command.HueSaturation{ hue=60 }
+  b = Color(255, 255, 0).rgbaPixel
+  expect_img(i, { b })
+
+  app.command.HueSaturation{ hue=60 }
+  b = Color(0, 255, 0).rgbaPixel
+  expect_img(i, { b })
+
+  app.command.HueSaturation{ saturation=-50 }
+  b = Color(64, 191, 64).rgbaPixel
+  expect_img(i, { b })
+
+  app.undo()
+  app.command.HueSaturation{ saturation=-100 }
+  b = Color(128, 128, 128).rgbaPixel
+  expect_img(i, { b })
+
+  app.undo()
+  app.command.HueSaturation{ saturation=-50, mode='hsv' }
+  b = Color(128, 255, 128).rgbaPixel
+  expect_img(i, { b })
+
+  app.undo()
+  app.command.HueSaturation{ value=75 }
+  b = Color(191, 255, 191).rgbaPixel
+  expect_img(i, { b })
+
+  app.undo()
+  app.command.HueSaturation{ alpha=-50 }
+  b = Color(0, 255, 0, 127).rgbaPixel
+  expect_img(i, { b })
+
+end
+
+do -- ColorCurve
+  local s = Sprite(2, 1)
+  local cel = app.activeCel
+  local i = cel.image
+
+  i:drawPixel(0, 0, rgba(255, 128, 0))
+  i:drawPixel(1, 0, rgba(64, 0, 32))
+  expect_img(i, { rgba(255, 128, 0), rgba(64, 0, 32) })
+
+  app.command.ColorCurve() -- Do nothing
+  expect_img(i, { rgba(255, 128, 0), rgba(64, 0, 32) })
+
+  app.command.ColorCurve{ curve={{0,0},{255,128}} }
+  expect_img(i, { rgba(128, 64, 0), rgba(32, 0, 16) })
+
+  app.command.ColorCurve{ channels=FilterChannels.ALPHA, curve={{0,0},{255,128}} }
+  expect_img(i, { rgba(128, 64, 0, 128), rgba(32, 0, 16, 128) })
+
+  app.command.ColorCurve{ channels=FilterChannels.RGBA, curve={{0,255},{255,255}} }
+  expect_img(i, { rgba(255, 255, 255), rgba(255, 255, 255) })
+
+  app.command.ColorCurve{ channels=FilterChannels.GREEN, curve={{0,0},{255,0}} }
+  expect_img(i, { rgba(255, 0, 255), rgba(255, 0, 255) })
+
+  app.command.ColorCurve{ channels=FilterChannels.BLUE, curve="0,128,255,128" }
+  expect_img(i, { rgba(255, 0, 128), rgba(255, 0, 128) })
+end
+
+do -- ConvolutionMatrix
+  local s = Sprite(3, 3)
+  local cel = app.activeCel
+  local i = cel.image
+  local b = rgba(0, 0, 0)
+  local w = rgba(255, 255, 255)
+
+  app.bgColor = Color(255, 255, 255)
+  app.command.BackgroundFromLayer()
+  i:drawPixel(1, 1, b)
+  expect_img(i, { w, w, w,
+                  w, b, w,
+                  w, w, w })
+
+  local u = rgba(239, 239, 239)
+  local v = rgba(223, 223, 223)
+  local w = rgba(191, 191, 191)
+  app.command.ConvolutionMatrix{ fromResource="blur-3x3" }
+  expect_img(i, { u, v, u,
+                  v, w, v,
+                  u, v, u })
+end
+
+-- MoveColors and CopyColors
+do
+  local s = Sprite(32, 32, ColorMode.INDEXED)
+  local p = Palette(4)
+  p:setColor(0, Color(0, 0, 0))
+  p:setColor(1, Color(255, 0, 0))
+  p:setColor(2, Color(0, 255, 0))
+  p:setColor(3, Color(0, 0, 255))
+  s:setPalette(p)
+  assert(#app.range.colors == 0)
+  app.range.colors = { 0, 2 }
+  assert(#app.range.colors == 2)
+  assert(app.range.colors[1] == 0)
+  assert(app.range.colors[2] == 2)
+  app.command.MoveColors{ before=0 }
+  p = s.palettes[1]
+  p:setColor(0, Color(0, 0, 0))
+  p:setColor(1, Color(0, 255, 0))
+  p:setColor(2, Color(255, 0, 0))
+  p:setColor(3, Color(0, 0, 255))
+
+  app.range.colors = { 0, 1 }
+  assert(#app.range.colors == 2)
+  assert(app.range.colors[1] == 0)
+  assert(app.range.colors[2] == 1)
+  app.command.CopyColors{ before=4 }
+  p = s.palettes[1]
+  p:setColor(0, Color(0, 0, 0))
+  p:setColor(1, Color(0, 255, 0))
+  p:setColor(2, Color(255, 0, 0))
+  p:setColor(3, Color(0, 0, 255))
+  p:setColor(4, Color(0, 0, 0))
+  p:setColor(5, Color(0, 255, 0))
+end
+
+-- AddColor
+do
+  local s = Sprite(32, 32)
+  local p = s.palettes[1]
+
+  function testAddColor(color)
+    assert(p:getColor(#p-1) ~= color)
+    app.command.AddColor{ color=color }
+    assert(p:getColor(#p-1) == color)
+  end
+  testAddColor(Color(255, 0, 0))
+  testAddColor(Color(0, 255, 0))
+  testAddColor(Color(0, 0, 255))
+
+  local color = Color(128, 0, 0)
+  app.preferences.color_bar.fg_color = color
+  app.command.AddColor{ source="fg" }
+  assert(p:getColor(#p-1) == color)
+
+  local color = Color(0, 0, 128)
+  app.preferences.color_bar.bg_color = color
+  app.command.AddColor{ source="bg" }
+  assert(p:getColor(#p-1) == color)
+end
+
+-- Flip
+do
+  local s = Sprite(4, 2, ColorMode.INDEXED)
+  local i = s.cels[1].image
+  array_to_pixels({ 0, 1, 2, 3,
+                    4, 5, 6, 7 }, i)
+  app.command.Flip{ orientation="horizontal" }
+  expect_img(i, { 3, 2, 1, 0,
+                  7, 6, 5, 4 })
+
+  app.command.Flip{ orientation="vertical" }
+  expect_img(i, { 7, 6, 5, 4,
+                  3, 2, 1, 0 })
+
+  s.selection:select{ 1, 0, 2, 2 }
+  app.command.Flip{ orientation="horizontal", target="mask" }
+  expect_img(i, { 7, 5, 6, 4,
+                  3, 1, 2, 0 })
+
+  s:newFrame()
+
+  assert(app.activeCel.frameNumber == 2)
+  local j = app.activeImage
+  app.command.Flip{ orientation="vertical", target="mask" }
+  expect_img(i, { 7, 5, 6, 4,
+                  3, 1, 2, 0 })
+  expect_img(j, { 7, 1, 2, 4,
+                  3, 5, 6, 0 })
+
+  app.range.frames = { 1, 2 }
+  app.command.Flip{ orientation="horizontal", target="mask" }
+  expect_img(i, { 7, 6, 5, 4,
+                  3, 2, 1, 0 })
+  expect_img(j, { 7, 2, 1, 4,
+                  3, 6, 5, 0 })
+end
+
+-- Fill
+do
+  local s = Sprite(4, 2, ColorMode.INDEXED)
+  local c = s.cels[1]
+  local i = c.image
+  i:clear(1)
+  array_to_pixels({ 1, 1, 1, 1,
+                    1, 1, 1, 1 }, i)
+  app.fgColor = Color{ index=0 }
+  s.selection = Selection(Rectangle(1, 1, 2, 1))
+  app.command.Fill()
+  expect_eq(Rectangle(0, 0, 4, 2), c.bounds)
+  expect_img(i, { 1, 1, 1, 1,
+                  1, 0, 0, 1 })
+
+  c.position = { x=0, y=1 }
+  app.fgColor = Color{ index=2 }
+  s.selection = Selection(Rectangle(1, 0, 2, 2))
+  app.command.Fill()
+  expect_eq(Rectangle(0, 0, 4, 3), c.bounds)
+  expect_img(i, { 0, 2, 2, 0,
+                  1, 2, 2, 1,
+                  1, 0, 0, 1 })
+
+  app.fgColor = Color{ index=0 }
+  s.selection = Selection(Rectangle(0, 0, 3, 3))
+  app.command.Fill()
+  expect_eq(Rectangle(3, 1, 1, 2), c.bounds)
+  expect_img(i, { 1,
+                  1 })
+
+  app.undo() -- undo Fill
+  expect_eq(Rectangle(0, 0, 4, 3), c.bounds)
+  expect_img(i, { 0, 2, 2, 0,
+                  1, 2, 2, 1,
+                  1, 0, 0, 1 })
+
+  expect_eq(Rectangle(0, 0, 3, 3), s.selection.bounds)
+  app.undo() -- undo selection change
+  expect_eq(Rectangle(1, 0, 2, 2), s.selection.bounds)
+  app.undo() -- undo Fill
+  expect_eq(Rectangle(0, 1, 4, 2), c.bounds)
+  expect_img(i, { 1, 1, 1, 1,
+                  1, 0, 0, 1 })
+end
diff --git a/tests/scripts/app_fs.lua b/tests/scripts/app_fs.lua
new file mode 100644
index 000000000..e3e38949c
--- /dev/null
+++ b/tests/scripts/app_fs.lua
@@ -0,0 +1,77 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local fs = app.fs
+local sep = fs.pathSeparator
+
+assert('' == fs.filePath('first.png'))
+assert('path' == fs.filePath('path/second.png'))
+assert('C:\\path' == fs.filePath('C:\\path\\third.png'))
+
+assert('first.png' == fs.fileName('first.png'))
+assert('second.png' == fs.fileName('path/second.png'))
+assert('third.png' == fs.fileName('C:\\path\\third.png'))
+
+assert('png' == fs.fileExtension('path/file.png'))
+
+assert('first' == fs.fileTitle('first.png'))
+assert('second' == fs.fileTitle('path/second.png'))
+assert('third' == fs.fileTitle('C:\\path\\third.png'))
+
+assert('first' == fs.filePathAndTitle('first.png'))
+assert('path/second' == fs.filePathAndTitle('path/second.png'))
+assert('C:\\path\\third' == fs.filePathAndTitle('C:\\path\\third.png'))
+
+assert('hi/bye' == fs.joinPath('hi/', 'bye'))
+assert('hi/bye' .. sep .. 'smth.png' == fs.joinPath('hi/', 'bye', 'smth.png'))
+
+local pwd = fs.currentPath
+assert(pwd ~= nil)
+assert(fs.isDirectory(pwd))
+assert(not fs.isFile(pwd))
+assert(fs.isFile(fs.joinPath(pwd, 'run-tests.sh')))
+
+do
+  local runTestsFound = false
+  local readmeFound = false
+  local files = fs.listFiles(pwd)
+  for i in pairs(files) do
+    if files[i] == 'run-tests.sh' then
+      runTestsFound = true
+    elseif files[i] == 'README.md' then
+      readmeFound = true
+    end
+
+    local fullFs = fs.joinPath(pwd, files[i])
+    if fs.isFile(fullFs) then
+      assert(fs.fileSize(fullFs) > 0)
+    end
+  end
+  assert(runTestsFound)
+  assert(readmeFound)
+end
+
+-- Create directories
+do
+  assert(fs.makeDirectory("_tmp"))
+  assert(fs.isDirectory("_tmp"))
+
+  assert(fs.makeAllDirectories("_tmp/a/b"))
+  assert(fs.isDirectory("_tmp/a"))
+  assert(fs.isDirectory("_tmp/a/b"))
+
+  assert(fs.removeDirectory("_tmp/a/b"))
+  assert(not fs.isDirectory("_tmp/a/b"))
+  assert(fs.isDirectory("_tmp/a"))
+
+  assert(not fs.removeDirectory("_tmp")) -- Should fail
+  assert(fs.isDirectory("_tmp/a"))
+  assert(fs.isDirectory("_tmp"))
+
+  assert(fs.removeDirectory("_tmp/a"))
+  assert(fs.removeDirectory("_tmp"))
+  assert(not fs.isDirectory("_tmp/a"))
+  assert(not fs.isDirectory("_tmp"))
+end
diff --git a/tests/scripts/app_pixel_color.lua b/tests/scripts/app_pixel_color.lua
new file mode 100644
index 000000000..a86c1d3f0
--- /dev/null
+++ b/tests/scripts/app_pixel_color.lua
@@ -0,0 +1,12 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local pc = app.pixelColor
+assert(0 == pc.rgba(0, 0, 0, 0))
+assert(1 == pc.rgbaR(pc.rgba(1, 2, 3, 4)))
+assert(2 == pc.rgbaG(pc.rgba(1, 2, 3, 4)))
+assert(3 == pc.rgbaB(pc.rgba(1, 2, 3, 4)))
+assert(4 == pc.rgbaA(pc.rgba(1, 2, 3, 4)))
+assert(0xff104080 == pc.rgba(0x80, 0x40, 0x10, 0xff))
diff --git a/tests/scripts/app_preferences.lua b/tests/scripts/app_preferences.lua
new file mode 100644
index 000000000..5c11bc82d
--- /dev/null
+++ b/tests/scripts/app_preferences.lua
@@ -0,0 +1,140 @@
+-- Copyright (C) 2019-2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+-- Preferences for tools
+do
+  -- The first time we get the tool preferences in CLI mode, we get
+  -- the default options for this tool (in GUI, we get the current
+  -- user-defined options).
+  local t = app.preferences.tool('pencil')
+  assert(t.opacity == 255)
+  assert(t.tolerance == 0)
+  assert(t.contiguous == true)
+  assert(t.brush.type == BrushType.CIRCLE)
+  assert(t.brush.size == 1)
+  t.brush.size = 2
+  assert(t.brush.size == 2)
+
+  -- Getting the tool again must give us the configuration that was
+  -- set inside the script
+  t = app.preferences.tool('pencil')
+  assert(t.brush.size == 2)
+end
+
+-- Preferences for documents
+do
+  local defPref = app.preferences.document(nil)
+  defPref.grid.bounds = Rectangle(0, 0, 16, 16)
+
+  local s = Sprite(32, 32)
+  local p = app.preferences.document(s)
+  assert(s.gridBounds == Rectangle(0, 0, 16, 16))
+  assert(p.grid.bounds == Rectangle(0, 0, 16, 16))
+  assert(p.grid.color == Color(0, 0, 255))
+  p.grid.color = Color(255, 0, 0)
+  assert(p.grid.color == Color(255, 0, 0))
+end
+
+-- Default & doc preferences combinations (related to https://community.aseprite.org/t/4305)
+do
+  -- Set default preferences
+  local defPref = app.preferences.document(nil)
+  defPref.grid.bounds = Rectangle(0, 0, 10, 10)
+  defPref.grid.color = Color(255, 255, 0) -- Yellow
+  assert(defPref.grid.bounds == Rectangle(0, 0, 10, 10))
+  assert(defPref.grid.color == Color(255, 255, 0))
+
+  do -- File with default preferences
+    local doc = Sprite(32, 32)
+    local docPref = app.preferences.document(doc)
+    assert(doc.gridBounds == Rectangle(0, 0, 10, 10))
+    assert(docPref.grid.bounds == Rectangle(0, 0, 10, 10))
+    assert(docPref.grid.color == Color(255, 255, 0))
+    doc:saveAs('_test_pref.png')
+    doc:close()
+  end
+
+  do -- File with specific preferences
+    local doc = Sprite(32, 32)
+    local docPref = app.preferences.document(doc)
+    docPref.grid.color = Color(0, 128, 0) -- Green
+    assert(docPref.grid.bounds == Rectangle(0, 0, 10, 10))
+    assert(docPref.grid.color == Color(0, 128, 0))
+    doc:saveAs('_test_pref2.png')
+    doc:close()
+  end
+
+  -- Now we change default preferences
+  defPref.grid.bounds = Rectangle(0, 0, 64, 64)
+  defPref.grid.color = Color(255, 0, 0) -- Red
+  assert(defPref.grid.bounds == Rectangle(0, 0, 64, 64))
+  assert(defPref.grid.color == Color(255, 0, 0))
+  do -- A new document should have the new default preferences
+    local doc = Sprite(32, 32)
+    local docPref = app.preferences.document(doc)
+    assert(docPref.grid.bounds == Rectangle(0, 0, 64, 64))
+    assert(docPref.grid.color == Color(255, 0, 0))
+    doc:close()
+  end
+  do -- The first document should have the new default preferences (because it was saved with the defaults)
+
+    -- TODO maybe related to https://community.aseprite.org/t/grid-for-new-documents/3303
+    --      should we get the new defaults or the values when we saved the document?
+    --      (e.g. even if we didn't change the grid values, it looks
+    --      like if the user changed something about the grid or the
+    --      background colors, the expected behavior would be to
+    --      restore the exact same colors, no the new defaults)
+
+    local doc = Sprite{ fromFile="_test_pref.png" }
+    local docPref = app.preferences.document(doc)
+    assert(docPref.grid.bounds == Rectangle(0, 0, 64, 64))
+    assert(docPref.grid.color == Color(255, 0, 0))
+    doc:close()
+  end
+  do -- The second document should have the new specific preferences for the grid color
+    local doc = Sprite{ fromFile="_test_pref2.png" }
+    local docPref = app.preferences.document(doc)
+    assert(docPref.grid.bounds == Rectangle(0, 0, 64, 64))
+    assert(docPref.grid.color == Color(0, 128, 0))
+    doc:close()
+  end
+end
+
+do -- Test that undoing grid bounds, updates the grid in the preferences correctly
+  local doc = Sprite(32, 32)
+  assert(doc.gridBounds == Rectangle(0, 0, 64, 64))
+  assert(app.preferences.document(doc).grid.bounds == Rectangle(0, 0, 64, 64))
+
+  doc.gridBounds = Rectangle(0, 0, 4, 4)
+  assert(doc.gridBounds == Rectangle(0, 0, 4, 4))
+  assert(app.preferences.document(doc).grid.bounds == Rectangle(0, 0, 4, 4))
+
+  app.undo()
+  assert(doc.gridBounds == Rectangle(0, 0, 64, 64))
+  assert(app.preferences.document(doc).grid.bounds == Rectangle(0, 0, 64, 64))
+
+  app.redo()
+  assert(doc.gridBounds == Rectangle(0, 0, 4, 4))
+  assert(app.preferences.document(doc).grid.bounds == Rectangle(0, 0, 4, 4))
+end
+
+do -- Test symmetry preferences
+  do -- File with default preferences
+    local doc = Sprite(200, 100)
+    local docPref = app.preferences.document(doc)
+    assert(docPref.symmetry.x_axis == 100)
+    assert(docPref.symmetry.y_axis == 50)
+    docPref.symmetry.x_axis = 25
+    doc:saveAs('_test_symmetry.png')
+    doc:close()
+  end
+  do -- File with default preferences
+    local doc = Sprite{ fromFile='_test_symmetry.png' }
+    local docPref = app.preferences.document(doc)
+    assert(docPref.symmetry.x_axis == 25)
+    assert(docPref.symmetry.y_axis == 50)
+    doc:close()
+  end
+end
diff --git a/tests/scripts/app_transaction.lua b/tests/scripts/app_transaction.lua
new file mode 100644
index 000000000..ea928b950
--- /dev/null
+++ b/tests/scripts/app_transaction.lua
@@ -0,0 +1,40 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local s = Sprite(16, 32)
+assert(s.width == 16)
+assert(s.height == 32)
+
+s.width = 20
+assert(s.width == 20)
+assert(s.height == 32)
+
+s.height = 40
+assert(s.width == 20)
+assert(s.height == 40)
+
+app.undo()
+assert(s.width == 20)
+assert(s.height == 32)
+
+app.undo()
+assert(s.width == 16)
+assert(s.height == 32)
+
+app.transaction(
+  function()
+    s.width = 20
+    s.height = 40
+  end)
+assert(s.width == 20)
+assert(s.height == 40)
+
+app.undo()
+assert(s.width == 16)
+assert(s.height == 32)
+
+app.redo()
+assert(s.width == 20)
+assert(s.height == 40)
diff --git a/tests/scripts/brush.lua b/tests/scripts/brush.lua
new file mode 100644
index 000000000..2f9accdeb
--- /dev/null
+++ b/tests/scripts/brush.lua
@@ -0,0 +1,74 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+do
+  local b = Brush()
+  assert(b.type == BrushType.CIRCLE)
+  assert(b.size == 1)
+  assert(b.angle == 0)
+  assert(b.center == Point{ x=0, y=0 })
+  assert(b.pattern == BrushPattern.NONE)
+  assert(b.patternOrigin == Point{ x=0, y=0 })
+
+  local c = Brush(3)
+  assert(c.type == BrushType.CIRCLE)
+  assert(c.size == 3)
+  assert(c.center == Point{ x=1, y=1 })
+
+  local d = Brush(4)
+  assert(d.type == BrushType.CIRCLE)
+  assert(d.size == 4)
+  assert(d.center == Point{ x=2, y=2 })
+end
+
+do
+  local b = Brush{ type=BrushType.SQUARE, size=4 }
+  assert(b.type == BrushType.SQUARE)
+  assert(b.size == 4)
+  assert(b.angle == 0)
+end
+
+do
+  local b = Brush{ type=BrushType.LINE, size=5, angle=90 }
+  assert(b.type == BrushType.LINE)
+  assert(b.size == 5)
+  assert(b.angle == 90)
+end
+
+do
+  local b = Brush{ type=BrushType.IMAGE, image=Image(4, 8) }
+  local c = Brush{ image=Image(4, 8) }
+  assert(b.type == BrushType.IMAGE)
+  assert(c.type == BrushType.IMAGE)
+  assert(b.image.width == 4)
+  assert(b.image.height == 8)
+  assert(b.pattern == BrushPattern.NONE)
+  assert(b.patternOrigin.x == 0)
+  assert(b.patternOrigin.y == 0)
+end
+
+do
+  local rgba = app.pixelColor.rgba
+  local r = rgba(255, 0, 0)
+  local g = rgba(0, 128, 0)
+  local b = rgba(0, 0, 255)
+
+  local img = Image(2, 2)
+  img:putPixel(0, 0, r)
+  img:putPixel(1, 0, b)
+  img:putPixel(0, 1, b)
+  img:putPixel(1, 1, r)
+
+  local brush = Brush{ image=img }
+  expect_img(brush.image, { r, b, b, r })
+
+  brush:setFgColor(g)
+  expect_img(brush.image, { r, g, g, r })
+
+  brush:setBgColor(b)
+  expect_img(brush.image, { b, g, g, b })
+end
diff --git a/tests/scripts/cel.lua b/tests/scripts/cel.lua
new file mode 100644
index 000000000..c7ee77905
--- /dev/null
+++ b/tests/scripts/cel.lua
@@ -0,0 +1,29 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local s = Sprite(32, 64)
+assert(#s.layers == 1)
+assert(#s.cels == 1)
+
+local c = s.cels[1]
+assert(c.sprite == s)
+assert(c.layer == s.layers[1])
+assert(c.frame == s.frames[1])
+assert(c.frame.frameNumber == 1)
+assert(c.frameNumber == 1)
+assert(c.image)
+assert(c.bounds == Rectangle(0, 0, 32, 64))
+assert(c.position == Point(0, 0))
+assert(c.color == Color())
+assert(c.data == "")
+
+c.color = Color{ r=255, g=100, b=20 }
+c.data = "test"
+assert(c.color == Color{ r=255, g=100, b=20 })
+assert(c.data == "test")
+
+c.position = Point(2, 4)
+assert(c.position == Point(2, 4))
+assert(c.bounds == Rectangle(2, 4, 32, 64))
diff --git a/tests/scripts/cels.lua b/tests/scripts/cels.lua
new file mode 100644
index 000000000..2c68aeab6
--- /dev/null
+++ b/tests/scripts/cels.lua
@@ -0,0 +1,86 @@
+-- Copyright (C) 2020  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+do
+  local s = Sprite(32, 32)
+  for i = 1,3 do s:newFrame() end
+  assert(#s.frames == 4)
+
+  -- Layer a and b
+  local a = s.layers[1]
+  local b = s:newLayer()
+
+  local ca = { s.cels[1],
+               s.cels[2],
+               s.cels[3] }
+
+  local cb = { s:newCel(b, 1),
+               s:newCel(b, 2, Image(8, 8), 4, 4),
+               s:newCel(b, 3, Image(32, 10), 16, 10) }
+
+  assert(cb[1].bounds == Rectangle(0, 0, 32, 32))
+  assert(cb[2].bounds == Rectangle(4, 4, 8, 8))
+  assert(cb[3].bounds == Rectangle(16, 10, 32, 10))
+
+  -- Check how layer cels are updated when we delete a cel in the middle
+
+  assert(cb[1] == b.cels[1])
+  assert(cb[2] == b.cels[2])
+  assert(cb[3] == b.cels[3])
+
+  local i = 1
+  for k,v in ipairs(b.cels) do
+    assert(i == k)
+    assert(v == b.cels[k])
+    i = i+1
+  end
+
+  s:deleteCel(cb[2])
+  assert(cb[1] == b.cels[1])
+  assert(cb[3] == b.cels[2])
+end
+
+-- Some extra tests of newCel() and deleteCel()
+do
+  local s = Sprite(4, 4, ColorMode.INDEXED)
+  local layer = app.activeLayer
+  app.bgColor = 0
+  app.command.BackgroundFromLayer()
+  expect_img(s.cels[1].image, { 0, 0, 0, 0,
+                                0, 0, 0, 0,
+                                0, 0, 0, 0,
+                                0, 0, 0, 0 })
+
+  -- Crash in old versions undoing newCel() in a background layer
+  s:newCel(layer, 1)
+  app.undo()
+
+  -- Check that newCel clears with bgColor in background layer
+  local img = Image(ImageSpec{ width=2, height=2,
+                               colorMode=ColorMode.INDEXED })
+  array_to_pixels({ 0, 1,
+                    2, 3 }, img)
+
+  app.bgColor = Color(1) -- bgColor used to clear the background cel
+  s:newCel(layer, 1, img, Point(1, 1))
+  expect_img(s.cels[1].image, { 1, 1, 1, 1,
+                                1, 0, 1, 1,
+                                1, 2, 3, 1,
+                                1, 1, 1, 1 })
+  app.undo()
+
+  -- Check deleteCel()
+  app.bgColor = Color(2)
+  s:deleteCel(layer, 1)
+  expect_img(s.cels[1].image, { 2, 2, 2, 2,
+                                2, 2, 2, 2,
+                                2, 2, 2, 2,
+                                2, 2, 2, 2 })
+  app.undo()
+
+end
diff --git a/tests/scripts/color.lua b/tests/scripts/color.lua
new file mode 100644
index 000000000..ab2751837
--- /dev/null
+++ b/tests/scripts/color.lua
@@ -0,0 +1,45 @@
+-- Copyright (C) 2022  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local a, b
+
+a = Color()
+assert(a.red == 0)
+assert(a.green == 0)
+assert(a.blue == 0)
+assert(a.alpha == 0)
+
+a = Color{ r=100, g=50, b=10 }
+b = Color(100, 50, 10)
+assert(a.red == 100)
+assert(a.green == 50)
+assert(a.blue == 10)
+assert(a.alpha == 255)
+assert(a == b)
+
+a = Color{ red=200, green=100, blue=20, alpha=200 }
+b = Color(200, 100, 20, 200)
+assert(a.red == 200)
+assert(a.green == 100)
+assert(a.blue == 20)
+assert(a.alpha == 200)
+assert(a == b)
+print(a.rgbaPixel)
+print(app.pixelColor.rgba(200, 100, 20, 200))
+assert(a.rgbaPixel == app.pixelColor.rgba(200, 100, 20, 200))
+
+a = Color{ h=180, s=0.4, v=0.5, a=200 }
+b = Color{ hue=180, saturation=0.4, value=0.5, alpha=200 }
+assert(a.hue == 180)
+assert(a.saturation == 0.4)
+assert(a.value == 0.5)
+assert(a.alpha == 200)
+assert(b.hue == 180)
+assert(b.saturation == 0.4)
+assert(b.value == 0.5)
+assert(b.alpha == 200)
+assert(a == b)
+assert(a ~= 1) -- Comparing with other type fails
diff --git a/tests/scripts/color_convert.lua b/tests/scripts/color_convert.lua
new file mode 100644
index 000000000..3babcef41
--- /dev/null
+++ b/tests/scripts/color_convert.lua
@@ -0,0 +1,51 @@
+-- Copyright (C) 2019-2022  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+-- this tests and ensures that the alpha-ness of a background
+-- layer is maintained when sprite conversion takes place from
+-- Indexed to RGB
+
+do
+  local sprite = Sprite(2, 2, ColorMode.INDEXED)
+  local pal = sprite.palettes[1]
+
+  assert(sprite.layers[1].isTransparent)
+  assert(sprite.colorMode == ColorMode.INDEXED)
+  assert(#pal == 256)
+
+  local color = pal:getColor(3)
+  color.alpha = 200
+  pal:setColor(3, color)
+
+  local image = sprite.cels[1].image
+  image:drawPixel(0, 0, pal:getColor(2))
+  image:drawPixel(0, 1, pal:getColor(3))
+  image:drawPixel(1, 0, pal:getColor(4))
+  image:drawPixel(1, 1, pal:getColor(5))
+
+  app.bgColor = Color{ index=0 }
+  app.command.BackgroundFromLayer()
+
+  local layer = sprite.layers[1]
+  assert(layer.isTransparent == false)
+  assert(layer.name == "Background")
+
+  -- change color mode from Indexed to RGB
+  app.command.ChangePixelFormat {
+    format="rgb"
+  }
+
+  assert(sprite.colorMode == ColorMode.RGB)
+  image = sprite.cels[1].image
+
+  for x=0, 1, 1 do
+    for y=0, 1, 1 do
+      local pixel = image:getPixel(x, y)
+      assert(app.pixelColor.rgbaA(pixel) == 255)
+    end
+  end
+end
diff --git a/tests/scripts/color_quantization.lua b/tests/scripts/color_quantization.lua
new file mode 100644
index 000000000..b37a9c13a
--- /dev/null
+++ b/tests/scripts/color_quantization.lua
@@ -0,0 +1,201 @@
+-- Copyright (C) 2019-2022  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile("./test_utils.lua")
+
+local rgba = app.pixelColor.rgba
+
+----------------------------------------------------------------------
+-- app.command.ColorQuantization
+
+do
+  -- One sprite with a background layer
+  local s = Sprite(2, 2)
+  app.command.BackgroundFromLayer()
+
+  local i = s.cels[1].image
+  local p = s.palettes[1]
+  assert(#p == 256)
+  assert(s.colorMode == ColorMode.RGB)
+  app.command.ColorQuantization{ algorithm="rgb5a3" }
+  assert(#p == 1)
+
+  array_to_pixels({ rgba(255, 255, 0), rgba(255, 255, 0),
+                    rgba(255, 255, 0), rgba(255, 255, 0) }, i)
+  app.command.ColorQuantization{ algorithm="rgb5a3" }
+  assert(#p == 1)
+  assert(p:getColor(0) == Color(255, 255, 0))
+
+  array_to_pixels({ rgba(255,   0, 0), rgba(255, 0,   0),
+                    rgba(255, 255, 0), rgba(255, 255, 0) }, i)
+  app.command.ColorQuantization{ algorithm="rgb5a3" }
+  assert(#p == 2)
+  assert(p:getColor(0) == Color(255, 0, 0))
+  assert(p:getColor(1) == Color(255, 255, 0))
+
+  array_to_pixels({ rgba(255,   0, 0), rgba(255, 0,   0),
+                    rgba(255, 255, 0), rgba(0,   0, 255) }, i)
+  app.command.ColorQuantization{ algorithm="rgb5a3" }
+  assert(#p == 3)
+  assert(p:getColor(0) == Color(255, 0, 0))
+  assert(p:getColor(1) == Color(255, 255, 0))
+  assert(p:getColor(2) == Color(0, 0, 255))
+
+  -- Convert the background layer to a transparent layer
+
+  app.command.LayerFromBackground()
+  app.command.ColorQuantization{ algorithm="rgb5a3", withAlpha=false }
+  assert(#p == 4) -- One extra color for transparent layer
+  assert(p:getColor(0) == Color(0, 0, 0))
+  assert(p:getColor(1) == Color(255, 0, 0))
+  assert(p:getColor(2) == Color(255, 255, 0))
+  assert(p:getColor(3) == Color(0, 0, 255))
+
+  app.command.ColorQuantization()
+  assert(#p == 4)
+  assert(p:getColor(0) == Color(0, 0, 0, 0))
+  assert(p:getColor(1) == Color(255, 0, 0))
+  assert(p:getColor(2) == Color(255, 255, 0))
+  assert(p:getColor(3) == Color(0, 0, 255))
+
+  array_to_pixels({ rgba(0,     0, 0), rgba(255, 0,   0),
+                    rgba(255,   0, 0), rgba(0,   0, 255) }, i)
+  app.command.ColorQuantization{ algorithm="rgb5a3", withAlpha=false }
+  assert(#p == 4)
+  assert(p:getColor(0) == Color(0, 0, 0))
+  assert(p:getColor(1) == Color(0, 0, 0))
+  assert(p:getColor(2) == Color(255, 0, 0))
+  assert(p:getColor(3) == Color(0, 0, 255))
+
+  app.command.ColorQuantization{ algorithm="rgb5a3" }
+  assert(#p == 4)
+  assert(p:getColor(0) == Color(0, 0, 0, 0))
+  assert(p:getColor(1) == Color(0, 0, 0))
+  assert(p:getColor(2) == Color(255, 0, 0))
+  assert(p:getColor(3) == Color(0, 0, 255))
+end
+
+do
+  -- One sprite with a transparent layer + a background layer
+  local s = Sprite(2, 2)
+  local p = s.palettes[1]
+  app.command.BackgroundFromLayer()
+  local bg = s.cels[1].image
+  local fg = s:newCel(s:newLayer(), 1).image
+
+  assert(#s.frames == 1)
+  assert(#s.layers == 2)
+  assert(#s.cels == 2)
+
+  array_to_pixels({ rgba(0, 0, 0, 0), rgba(0, 255, 0),
+                    rgba(255, 0, 0), rgba(0, 0, 0, 0) }, fg)
+  array_to_pixels({ rgba(0, 0, 0), rgba(0, 0, 0),
+                    rgba(0, 0, 0), rgba(0, 0, 255) }, bg)
+
+  app.command.ColorQuantization{ algorithm="rgb5a3" }
+  assert(#p == 5)
+  assert(p:getColor(0) == Color(0, 0, 0, 0))
+  assert(p:getColor(1) == Color(0, 0, 0))
+  assert(p:getColor(2) == Color(0, 255, 0))
+  assert(p:getColor(3) == Color(255, 0, 0))
+  assert(p:getColor(4) == Color(0, 0, 255))
+end
+
+----------------------------------------------------------------------
+-- app.command.ChangePixelFormat
+
+do
+  local s = Sprite(2, 2, ColorMode.RGB)
+  local p = Palette(4)
+  p:setColor(0, Color(0, 0, 0))
+  p:setColor(1, Color(101, 90, 200))
+  p:setColor(2, Color(102, 91, 201))
+  p:setColor(3, Color(103, 92, 203))
+  s:setPalette(p)
+
+  app.command.BackgroundFromLayer()
+
+  local bg = s.cels[1].image
+  array_to_pixels({ rgba(0, 0, 0), rgba(101, 90, 200),
+                    rgba(102, 91, 201), rgba(103, 92, 203) }, bg)
+
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="rgb5a3" }
+  -- Using the 5-bit precision of RGB5A3 will match everything with
+  -- the first palette entry.
+  bg = s.cels[1].image
+  expect_img(bg, { 0, 1,
+                   1, 1 })
+  app.undo()
+
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="octree" }
+  bg = s.cels[1].image
+  expect_img(bg, { 0, 1,
+                   2, 3 })
+  app.undo()
+
+  p:setColor(0, Color(0, 0, 0, 0))
+  bg = s.cels[1].image
+  array_to_pixels({ rgba(101, 90, 200, 0), rgba(101, 90, 200),
+                    rgba(102, 91, 201), rgba(103, 92, 203, 0) }, bg)
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="octree" }
+  bg = s.cels[1].image
+  expect_img(bg, { 0, 1,
+                   2, 0 })
+
+end
+
+----------------------------------------------------------------------
+-- Tests for issue aseprite/aseprite#3207
+-- Conversion RGB to INDEXED color mode, in transparent layers, always
+-- picks index 0 as transparent color, even if the mask color is present
+-- in the palette.
+
+do
+  local s = Sprite(2, 3, ColorMode.RGB)
+  local p = Palette(4)
+  p:setColor(0, Color(0, 0, 0))
+  p:setColor(1, Color(255, 0, 0))
+  p:setColor(2, Color(0, 0, 0, 0))
+  p:setColor(3, Color(0, 255, 0))
+  s:setPalette(p)
+
+  local bg = s.cels[1].image
+  array_to_pixels({ rgba(0, 0, 0),rgba(255, 0, 0),
+                    rgba(255, 0, 0), rgba(0, 0, 0, 0),
+                    rgba(0, 0, 0, 0), rgba(0, 0, 0, 0), }, bg)
+
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="rgb5a3" }
+  -- Using the 5-bit precision of RGB5A3 will match everything with
+  -- the first palette entry.
+  bg = s.cels[1].image
+  expect_img(bg, { 0, 1,
+                   1, 2,
+                   2, 2 })
+  app.undo()
+
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="octree" }
+  bg = s.cels[1].image
+  expect_img(bg, { 0, 1,
+                   1, 2,
+                   2, 2 })
+  app.undo()
+
+  p:setColor(2, Color(0, 0, 255))
+  s:setPalette(p)
+  bg = s.cels[1].image
+
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="rgb5a3" }
+  bg = s.cels[1].image
+  expect_img(bg, { 2, 1,
+                   1, 0,
+                   0, 0 })
+  app.undo()
+
+  app.command.ChangePixelFormat{ format="indexed", rgbmap="octree" }
+  bg = s.cels[1].image
+  expect_img(bg, { 2, 1,
+                   1, 0,
+                   0, 0 })
+end
diff --git a/tests/scripts/color_space.lua b/tests/scripts/color_space.lua
new file mode 100644
index 000000000..103c89209
--- /dev/null
+++ b/tests/scripts/color_space.lua
@@ -0,0 +1,21 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local none = ColorSpace()         -- None
+local srgb = ColorSpace{ sRGB=true }
+local none2 = ColorSpace{ sRGB=false }
+assert(none ~= srgb)
+assert(none == none2)
+
+local spr = Sprite(32, 32)
+local cs1 = spr.colorSpace
+local cs2 = spr.spec.colorSpace
+assert(cs1 == cs2)
+assert(cs1 ~= none)
+assert(cs1 == srgb)    -- Default color profile: sRGB
+
+local spr3 = Sprite(32, 32)
+local cs3 = spr.spec.colorSpace
+assert(cs1 == cs3)
diff --git a/tests/scripts/compare_sprite_sheets.lua b/tests/scripts/compare_sprite_sheets.lua
new file mode 100644
index 000000000..d786ceb7b
--- /dev/null
+++ b/tests/scripts/compare_sprite_sheets.lua
@@ -0,0 +1,60 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local file1 = app.params["file1"]
+local file2 = app.params["file2"]
+if file1 == nil or file2 == nil then
+  return 0
+end
+
+local json = dofile('../third_party/json/json.lua')
+local data1 = json.decode(io.open(file1):read('a'))
+local data2 = json.decode(io.open(file2):read('a'))
+
+if data1 == nil then
+  print('Cannot read file ' .. file1)
+  return 1
+elseif data2 == nil then
+  print('Cannot read file ' .. file2)
+  return 1
+end
+
+local function replace_filename(fn, newfn)
+  return string.gsub(fn, "(.*)[/\\]([^/\\]+)", "%1/"..newfn)
+end
+
+local sheet1 = app.open(replace_filename(file1, data1.meta.image))
+local sheet2 = app.open(replace_filename(file2, data2.meta.image))
+
+for k,v in pairs(data1.frames) do
+  local fr1 = data1.frames[k]
+  local fr2 = data2.frames[k]
+  if fr1.duration ~= fr2.duration then
+    print('Frame '..k..' doesn\'t match duration')
+    return 1
+  end
+  if fr1.sourceSize.w ~= fr2.sourceSize.w or
+     fr1.sourceSize.h ~= fr2.sourceSize.h then
+    print('Frame '..k..' doesn\'t match sourceSize')
+    return 1
+  end
+
+  local celImage1 = Image(fr1.frame.w, fr1.frame.h, sheet1.colorMode)
+  local celImage2 = Image(fr2.frame.w, fr2.frame.h, sheet2.colorMode)
+  celImage1:drawSprite(sheet1, 1, -fr1.frame.x, -fr1.frame.y)
+  celImage2:drawSprite(sheet2, 1, -fr2.frame.x, -fr2.frame.y)
+
+  local frImage1 = Image(fr1.sourceSize.w, fr1.sourceSize.h, sheet1.colorMode)
+  local frImage2 = Image(fr2.sourceSize.w, fr2.sourceSize.h, sheet2.colorMode)
+  frImage1:drawImage(celImage1, fr1.spriteSourceSize.x, fr1.spriteSourceSize.y)
+  frImage2:drawImage(celImage2, fr2.spriteSourceSize.x, fr2.spriteSourceSize.y)
+
+  -- To debug this function
+  --frImage1:saveAs(replace_filename(file1, k .. "-fr1.png"))
+  --frImage2:saveAs(replace_filename(file2, k .. "-fr2.png"))
+  --print(k, "fr1", fr1.frame.x, fr1.frame.y, "fr2", fr2.frame.x, fr2.frame.y)
+
+  assert(frImage1:isEqual(frImage2))
+end
diff --git a/tests/scripts/console_assert.lua b/tests/scripts/console_assert.lua
new file mode 100644
index 000000000..2587e9675
--- /dev/null
+++ b/tests/scripts/console_assert.lua
@@ -0,0 +1,9 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+assert(true)
+print("this should be in the output")
+assert(false)
+print("this should not be in the output")
diff --git a/tests/scripts/console_print.lua b/tests/scripts/console_print.lua
new file mode 100644
index 000000000..dc402169a
--- /dev/null
+++ b/tests/scripts/console_print.lua
@@ -0,0 +1,7 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+print("hello world")
+print(1, 2, 3)
diff --git a/tests/scripts/constants.lua b/tests/scripts/constants.lua
new file mode 100644
index 000000000..8eb9ab970
--- /dev/null
+++ b/tests/scripts/constants.lua
@@ -0,0 +1,8 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+assert(ColorMode.RGB == 0)
+assert(ColorMode.GRAYSCALE == 1)
+assert(ColorMode.INDEXED == 2)
diff --git a/tests/scripts/drawing.lua b/tests/scripts/drawing.lua
new file mode 100644
index 000000000..a4b40332a
--- /dev/null
+++ b/tests/scripts/drawing.lua
@@ -0,0 +1,83 @@
+-- Copyright (C) 2018-2022  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local pc = app.pixelColor
+
+-- Image:clear
+local function test_clear(colorMode, transparentColor)
+  local i = Image(ImageSpec{ width=2, height=2, colorMode=colorMode, transparentColor=transparentColor })
+  i:putPixel(0, 0, 1)
+  i:putPixel(1, 0, 2)
+  i:putPixel(0, 1, 3)
+  i:putPixel(1, 1, 4)
+  assert(1 == i:getPixel(0, 0))
+  assert(2 == i:getPixel(1, 0))
+  assert(3 == i:getPixel(0, 1))
+  assert(4 == i:getPixel(1, 1))
+  i:clear(5)
+  assert(5 == i:getPixel(0, 0))
+  assert(5 == i:getPixel(1, 0))
+  assert(5 == i:getPixel(0, 1))
+  assert(5 == i:getPixel(1, 1))
+
+  print("transparentColor = ", transparentColor)
+  assert(transparentColor == i.spec.transparentColor)
+
+  i:clear()  -- Image:clear() clears with i.spec.transparentColor by default
+  assert(transparentColor == i:getPixel(0, 0))
+  assert(transparentColor == i:getPixel(1, 0))
+  assert(transparentColor == i:getPixel(0, 1))
+  assert(transparentColor == i:getPixel(1, 1))
+end
+test_clear(ColorMode.RGB, 0)
+test_clear(ColorMode.GRAYSCALE, 0)
+test_clear(ColorMode.INDEXED, 0)
+test_clear(ColorMode.INDEXED, 255)
+
+-- Image:drawSprite
+do
+   local spr = Sprite(4, 4)
+   local cel = spr.cels[1]
+   cel.image:putPixel(0, 0, pc.rgba(255, 0, 0, 255))
+   cel.image:putPixel(1, 0, pc.rgba(0, 255, 0, 255))
+   cel.image:putPixel(0, 1, pc.rgba(0, 0, 255, 255))
+   cel.image:putPixel(1, 1, pc.rgba(255, 255, 0, 255))
+
+   local r = Image(spr.spec) -- render
+   r:drawSprite(spr, 1, 0, 0)
+
+   assert(r:getPixel(0, 0) == pc.rgba(255, 0, 0, 255))
+   assert(r:getPixel(1, 0) == pc.rgba(0, 255, 0, 255))
+   assert(r:getPixel(0, 1) == pc.rgba(0, 0, 255, 255))
+   assert(r:getPixel(1, 1) == pc.rgba(255, 255, 0, 255))
+
+   r = Image(3, 3, spr.colorMode)
+   r:drawSprite(spr, 1, Point{x=1, y=1})
+   assert(r:getPixel(0, 0) == pc.rgba(0, 0, 0, 0))
+   assert(r:getPixel(1, 0) == pc.rgba(0, 0, 0, 0))
+   assert(r:getPixel(2, 0) == pc.rgba(0, 0, 0, 0))
+   assert(r:getPixel(0, 1) == pc.rgba(0, 0, 0, 0))
+   assert(r:getPixel(1, 1) == pc.rgba(255, 0, 0, 255))
+   assert(r:getPixel(2, 1) == pc.rgba(0, 255, 0, 255))
+   assert(r:getPixel(0, 2) == pc.rgba(0, 0, 0, 0))
+   assert(r:getPixel(1, 2) == pc.rgba(0, 0, 255, 255))
+   assert(r:getPixel(2, 2) == pc.rgba(255, 255, 0, 255))
+end
+
+
+-- Image:drawPixel with indexed color
+do
+  local a = Sprite(32, 32, ColorMode.INDEXED)
+  local i = a.cels[1].image
+  assert(i:getPixel(0, 0) == 0)
+  assert(i:getPixel(1, 0) == 0)
+  assert(i:getPixel(2, 0) == 0)
+  i:drawPixel(0, 0, Color{ index=2 })
+  i:drawPixel(1, 0, Color{ index=3 }.index)
+  i:drawPixel(2, 0, Color(4))
+  assert(i:getPixel(0, 0) == 2)
+  assert(i:getPixel(1, 0) == 3)
+  assert(i:getPixel(2, 0) == 4)
+end
diff --git a/tests/scripts/events.lua b/tests/scripts/events.lua
new file mode 100644
index 000000000..0a523bb45
--- /dev/null
+++ b/tests/scripts/events.lua
@@ -0,0 +1,136 @@
+-- Copyright (C) 2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+-- Test app.events
+do
+  local i = 0
+  local listener = app.events:on('sitechange',
+                                 function() i = i + 1 end)
+  assert(i == 0)
+  local a = Sprite(32, 32)
+  expect_eq(a, app.activeSprite)
+  expect_eq(1, i)
+  local b = Sprite(32, 32)
+  expect_eq(b, app.activeSprite)
+  expect_eq(2, i)
+  app.activeSprite = a
+  expect_eq(3, i)
+  app.events:off(listener)
+  app.activeSprite = b
+  expect_eq(3, i)
+end
+
+do
+  local pref = app.preferences
+  pref.color_bar.fg_color = Color(0, 0, 0)
+  pref.color_bar.bg_color = Color(0, 0, 0)
+
+  local fg, bg = 0, 0
+  local a = app.events:on('fgcolorchange', function() fg = fg + 1 end)
+  local b = app.events:on('bgcolorchange', function() bg = bg + 1 end)
+  assert(fg == 0)
+  assert(bg == 0)
+
+  pref.color_bar.fg_color = Color(255, 0, 0)
+  pref.color_bar.bg_color = Color(255, 0, 0)
+  assert(fg == 1)
+  assert(bg == 1)
+  pref.color_bar.fg_color = Color(255, 0, 0) -- No change (same color)
+  assert(fg == 1)
+  pref.color_bar.fg_color = Color(0, 0, 0)
+  assert(fg == 2)
+  app.events:off(a)
+  app.events:off(b)
+  pref.color_bar.fg_color = Color(255, 0, 0)
+  assert(fg == 2)
+end
+
+-- Test Sprite.events
+do
+  local spr = Sprite(32, 64)
+  local changes = 0
+  function incChanges() changes = changes + 1 end
+  spr.events:on('change', incChanges)
+  expect_eq(0, changes)
+  spr.width = 64
+  expect_eq(1, changes)
+  app.undo()
+  expect_eq(2, changes)
+  app.redo()
+  expect_eq(3, changes)
+  spr.events:off(incChanges)
+  app.undo()
+  expect_eq(3, changes)
+end
+
+-- Multiple listeners
+do
+  local spr = Sprite(2, 2)
+  local ai, bi = 0, 0
+  function a() ai = ai + 1 end
+  function b() bi = bi + 1 end
+
+  spr.events:on('change', a)
+  spr.events:on('change', b)
+  spr.width = 4
+  expect_eq(1, ai)
+  expect_eq(1, bi)
+
+  spr.events:off(a)
+  spr.width = 8
+  expect_eq(1, ai)
+  expect_eq(2, bi)
+
+  spr.events:off(b)
+  spr.width = 16
+  expect_eq(1, ai)
+  expect_eq(2, bi)
+end
+
+-- Avoid removing invalid listener when we use Events:off(function)
+do
+  local spr = Sprite(2, 2)
+
+  local i = 0
+  function inc() i = i + 1 end
+  spr.events:on('change', inc)
+
+  spr.width = 4
+  expect_eq(1, i)
+
+  app.events:off(inc)
+  spr.width = 8
+
+  -- If this fails is because app.events:off(inc) removed the sprite
+  -- listener instead of doing nothing.
+  expect_eq(2, i)
+end
+
+-- Accessing Sprite.events when closing the same sprite will call
+-- push_sprite_events() creating a new app::script::SpriteEvents
+-- instance again even when we've just destroyed the old one (because
+-- we're just closing the sprite).
+do
+  local s = Sprite(32, 32)
+  function onSpriteChange()
+    -- Do nothing
+  end
+  -- Here we access s.events for first time, creating the
+  -- app::script::SpriteEvents for this sprite.
+  s.events:on('change', onSpriteChange)
+  function onSiteChange()
+    -- Accessing s.events again on 'sitechange' when we're just
+    -- closing the sprite, re-generating its SpriteEvents instance.
+    -- We've to have special care of this case.
+    s.events:off(onSpriteChange)
+  end
+  app.events:on('sitechange', onSiteChange)
+  -- Closing the sprite will create a 'sitechange' event calling
+  -- onSiteChange() function.
+  s:close()
+  app.events:off(onSiteChange)
+end
diff --git a/tests/scripts/frames.lua b/tests/scripts/frames.lua
new file mode 100644
index 000000000..b33a668d6
--- /dev/null
+++ b/tests/scripts/frames.lua
@@ -0,0 +1,95 @@
+-- Copyright (C) 2018  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local a = Sprite(32, 32)
+  assert(#a.frames == 1)
+  assert(a.frames[1].frameNumber == 1)
+  assert(a.frames[1].duration == 0.1)
+  a.frames[1].duration = 0.2
+  assert(a.frames[1].duration == 0.2)
+  assert(a.layers[1]:cel(1) ~= nil)
+
+  -- Sprite:newEmptyFrame()
+  local fr0 = a:newEmptyFrame()
+  assert(fr0.frameNumber == 2) -- returned the second frame
+  assert(#a.frames == 2)
+  assert(a.frames[1].frameNumber == 1)
+  assert(a.frames[2].frameNumber == 2)
+  assert(a.frames[1].duration == 0.2)
+  assert(a.frames[2].duration == 0.2) -- the duration is copied
+  assert(a.layers[1]:cel(1) ~= nil)
+  assert(a.layers[1]:cel(fr0) == nil) -- no cel
+  assert(fr0 == a.frames[2])
+  a:deleteFrame(fr0)
+  assert(#a.frames == 1)
+
+  -- Sprite:newFrame() without arguments
+  local fr = a:newFrame()
+  assert(fr.frameNumber == 2) -- returned the second frame
+  assert(#a.frames == 2)
+  assert(a.frames[1].frameNumber == 1)
+  assert(a.frames[2].frameNumber == 2)
+  assert(a.frames[1].duration == 0.2)
+  assert(a.frames[2].duration == 0.2)
+  assert(fr == a.frames[2])
+
+  fr.duration = 0.3
+  assert(a.frames[1].duration == 0.2)
+  assert(a.frames[2].duration == 0.3)
+
+  local i = 1
+  for k,v in ipairs(a.frames) do
+    assert(i == k)
+    assert(v == a.frames[k])
+    i = i+1
+  end
+
+  a:deleteFrame(1)
+  assert(#a.frames == 1)
+  assert(a.frames[1].duration == 0.3)
+
+  -- TODO This is a big issue, if we add/delete frames, we don't
+  --      update frame objects, they are still pointing to the same frame
+  --      number, which could lead to confusion.
+  assert(fr.frameNumber == 2)
+  fr.duration = 1   -- This is a do nothing operation
+
+  -- Sprite:newEmptyFrame(n)
+  local fr2 = a:newEmptyFrame(1)
+  assert(#a.frames == 2)
+  assert(fr2.frameNumber == 1) -- returned the first frame
+  print(a.frames[1].duration)
+  assert(a.frames[1].duration == 0.3) -- the duration is copied from the frame
+  assert(a.frames[2].duration == 0.3)
+  assert(fr2 == a.frames[1])
+  assert(a.layers[1]:cel(1) == nil)
+  assert(a.layers[1]:cel(2) ~= nil)
+
+  -- Sprite:newFrame(n)
+  local fr3 = a:newFrame(2)
+  assert(#a.frames == 3)
+  assert(fr3.frameNumber == 2) -- returned the second frame
+  assert(a.frames[1].duration == 0.3)
+  assert(a.frames[2].duration == 0.3) -- copied duration from old frame 2
+  assert(a.frames[3].duration == 0.3)
+  local cel1 = a.layers[1]:cel(1)
+  local cel2 = a.layers[1]:cel(2)
+  local cel3 = a.layers[1]:cel(3)
+  assert(cel1 == nil)
+  assert(cel2 ~= nil)
+  assert(cel3 ~= nil)
+  print(cel2.image.spec.colorMode)
+  print(cel2.image.spec.width)
+  print(cel2.image.spec.height)
+  print(cel3.image.spec.colorMode)
+  print(cel3.image.spec.width)
+  print(cel3.image.spec.height)
+  assert(cel2.image.spec == cel3.image.spec)
+  assert(fr3.previous == a.frames[1])
+  assert(fr3 == a.frames[2])
+  assert(fr3.next == a.frames[3])
+end
diff --git a/tests/scripts/image.lua b/tests/scripts/image.lua
new file mode 100644
index 000000000..3bbe430af
--- /dev/null
+++ b/tests/scripts/image.lua
@@ -0,0 +1,276 @@
+-- Copyright (C) 2019-2022  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+local rgba = app.pixelColor.rgba
+
+local a = Image(32, 64)
+assert(a.width == 32)
+assert(a.height == 64)
+assert(a.colorMode == ColorMode.RGB) -- RGB by default
+assert(a.rowStride == 32*4)
+assert(a:isEmpty())
+assert(a:isPlain(rgba(0, 0, 0, 0)))
+assert(a:isPlain(0))
+
+do
+  local b = Image(32, 64, ColorMode.INDEXED)
+  assert(b.width == 32)
+  assert(b.height == 64)
+  assert(b.colorMode == ColorMode.INDEXED)
+  assert(b.rowStride == 32*1)
+
+  local c = Image{ width=32, height=64, colorMode=ColorMode.INDEXED }
+  assert(c.width == 32)
+  assert(c.height == 64)
+  assert(c.colorMode == ColorMode.INDEXED)
+end
+
+-- Get/put RGBA pixels
+do
+  for y=0,a.height-1 do
+    for x=0,a.width-1 do
+      a:putPixel(x, y, rgba(x, y, x+y, x-y))
+    end
+  end
+  assert(not a:isEmpty())
+end
+
+-- Clone
+do
+  local c = Image(a)
+  local d = a:clone()
+  assert(c.width == 32)
+  assert(c.height == 64)
+  assert(c.colorMode == ColorMode.RGB)
+  assert(c.width == d.width)
+  assert(c.height == d.height)
+  assert(c.colorMode == d.colorMode)
+
+  -- Get RGB pixels
+  for y=0,c.height-1 do
+    for x=0,c.width-1 do
+      local expectedColor = rgba(x, y, x+y, x-y)
+      assert(c:getPixel(x, y) == expectedColor)
+      assert(d:getPixel(x, y) == expectedColor)
+    end
+  end
+
+  -- Clone a rectangle
+  local e = Image(c, Rectangle(1, 1, 4, 5))
+  print(e.width)
+  print(e.height)
+  assert(e.width == 4)
+  assert(e.height == 5)
+
+  -- Empty clone
+  assert(nil == Image(c, Rectangle(1, 1, 0, 0)))
+end
+
+-- Patch
+do
+  local spr = Sprite(256, 256)
+  local image = app.site.image
+  local copy = image:clone()
+  assert(image:getPixel(0, 0) == 0)
+  for y=0,copy.height-1 do
+    for x=0,copy.width-1 do
+      copy:putPixel(x, y, rgba(255-x, 255-y, 0, 255))
+    end
+  end
+  image:putImage(copy)
+  assert(image:getPixel(0, 0) == rgba(255, 255, 0, 255))
+  assert(image:getPixel(255, 255) == rgba(0, 0, 0, 255))
+  app.undo()
+  assert(image:getPixel(0, 0) == rgba(0, 0, 0, 0))
+  assert(image:getPixel(255, 255) == rgba(0, 0, 0, 0))
+end
+
+-- Load/Save
+do
+  local a = Image{ fromFile="sprites/1empty3.aseprite" }
+  assert(a.width == 32)
+  assert(a.height == 32)
+  a:saveAs("_test_oneframe.png")
+
+  local b = Image{ fromFile="_test_oneframe.png" }
+  assert(b.width == 32)
+  assert(b.height == 32)
+  for y=0,a.height-1 do
+    for x=0,a.width-1 do
+      assert(a:getPixel(x, y) == b:getPixel(x, y))
+    end
+  end
+end
+
+-- Save indexed image and load and check that the palette is the same
+do
+  local spr = Sprite{ fromFile="sprites/abcd.aseprite" }
+  local img = Image{ fromFile="sprites/abcd.aseprite" }
+  spr.cels[1].image:saveAs("_test_palette_a.png")
+  img:saveAs("_test_palette_b.png") -- This file will contain a black palette
+  img:saveAs{ filename="_test_palette_c.png", palette=spr.palettes[1] }
+
+  local a = Sprite{ fromFile="_test_palette_a.png" }
+  local b = Sprite{ fromFile="_test_palette_b.png" }
+  local c = Sprite{ fromFile="_test_palette_c.png" }
+
+  assert(a.width == 5)
+  assert(a.height == 7)
+  assert(b.width == 32)
+  assert(b.height == 32)
+  assert(c.width == 32)
+  assert(c.height == 32)
+  local bimg = b.cels[1].image
+  local cimg = c.cels[1].image
+  for y=0,31 do
+    for x=0,31 do
+      assert(bimg:getPixel(x, y) == cimg:getPixel(x, y))
+    end
+  end
+
+  local apal = a.palettes[1]
+  local bpal = b.palettes[1]
+  local cpal = c.palettes[1]
+  -- Same palette in a and c
+  assert(#apal == #cpal)
+  for i=0,#apal-1 do
+    assert(apal:getColor(i) == cpal:getColor(i))
+  end
+  -- b should contain a complete black palette
+  assert(bpal:getColor(0) == Color(0, 0, 0, 0))
+  for i=1,#bpal-1 do
+    assert(bpal:getColor(i) == Color(0, 0, 0, 255))
+  end
+end
+
+-- Resize image
+do
+  local a = Sprite(3, 2)
+  local cel = a.cels[1]
+  assert(cel.bounds == Rectangle(0, 0, 3, 2))
+  local img = cel.image
+  local cols = { rgba(10, 60, 1), rgba(20, 50, 2), rgba(30, 40, 3),
+                 rgba(40, 30, 4), rgba(50, 20, 5), rgba(60, 10, 6) }
+  array_to_pixels(cols, img)
+  expect_img(img, cols)
+
+  -- Test resize of a cel with origin=0,0
+
+  img:resize(img.width*2, img.height*2)
+
+  expect_eq(cel.bounds, Rectangle(0, 0, 6, 4))
+  expect_eq(img.width, 6)
+  expect_eq(img.height, 4)
+  local cols2 = { cols[1],cols[1], cols[2],cols[2], cols[3],cols[3],
+                  cols[1],cols[1], cols[2],cols[2], cols[3],cols[3],
+                  cols[4],cols[4], cols[5],cols[5], cols[6],cols[6],
+                  cols[4],cols[4], cols[5],cols[5], cols[6],cols[6] }
+  expect_img(img, cols2)
+
+  -- Undo
+  function undo()
+    app.undo()
+    img = cel.image -- TODO img shouldn't be invalidated, the resize operation should kept the image ID
+  end
+  undo()
+
+  -- Test a resize when cel origin > 0,0
+  cel.position = Point(2, 1)
+  expect_eq(cel.bounds, Rectangle(2, 1, 3, 2))
+  expect_img(img, cols)
+  img:resize{ width=6, height=4 }
+  expect_eq(cel.bounds, Rectangle(2, 1, 6, 4)) -- Position is not modified
+  expect_eq(img.width, 6)
+  expect_eq(img.height, 4)
+
+  undo()
+  img:resize{ size=Size(6, 4), pivot=Point(1, 1) }
+  expect_eq(cel.bounds, Rectangle(1, 0, 6, 4))
+
+  undo()
+  img:resize{ size=Size(6, 4), pivot=Point(3, 2) }
+  expect_eq(cel.bounds, Rectangle(-1, -1, 6, 4))
+
+  -- Test resize without cel
+
+  local img2 = Image(img)
+  expect_img(img2, cols2)
+  img2:resize(3, 2)
+  expect_img(img2, cols)
+end
+
+-- Test v1.2.17 crashes
+do
+  local defSpec = ImageSpec{ width=1, height=1, colorMode=ColorMode.RGB }
+
+  local img = Image() -- we create a 1x1 RGB image
+  assert(img ~= nil)
+  assert(img.spec == defSpec)
+
+  img = Image(nil)
+  assert(img ~= nil)
+  assert(img.spec == defSpec)
+
+  local spr = Sprite(32, 32, ColorMode.INDEXED)
+  spr.cels[1].image:putPixel(15, 15, 129)
+  img = Image(spr)    -- we create a sprite render of the first frame
+  assert(img ~= nil)
+  assert(img.spec == spr.spec)
+  assert(img:getPixel(15, 15) == 129)
+end
+
+-- Fix drawImage() when drawing in a cel image
+do
+  local a = Image(3, 2, ColorMode.INDEXED)
+  array_to_pixels({ 0, 1, 2,
+                    2, 3, 4 }, a)
+
+  local function test(b)
+    expect_img(b, { 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0 })
+
+    b:drawImage(a, Point(2, 1))
+    expect_img(b, { 0, 0, 0, 0, 0,
+                    0, 0, 0, 1, 2,
+                    0, 0, 2, 3, 4,
+                    0, 0, 0, 0, 0 })
+
+    b:drawImage(a, Point(0, 1))
+    expect_img(b, { 0, 0, 0, 0, 0,
+                    0, 1, 2, 1, 2,
+                    2, 3, 4, 3, 4,
+                    0, 0, 0, 0, 0 })
+
+    b:drawImage(a, Point(-1, 2))
+    expect_img(b, { 0, 0, 0, 0, 0,
+                    0, 1, 2, 1, 2,
+                    1, 2, 4, 3, 4,
+                    3, 4, 0, 0, 0 })
+
+    b:drawImage(a, Point(0, 3))
+    expect_img(b, { 0, 0, 0, 0, 0,
+                    0, 1, 2, 1, 2,
+                    1, 2, 4, 3, 4,
+                    0, 1, 2, 0, 0 })
+
+    b:drawImage(a, Point(0, 3)) -- Do nothing
+    expect_img(b, { 0, 0, 0, 0, 0,
+                    0, 1, 2, 1, 2,
+                    1, 2, 4, 3, 4,
+                    0, 1, 2, 0, 0 })
+  end
+
+  local b = Image(5, 4, ColorMode.INDEXED)
+  test(b)
+
+  local s = Sprite(5, 4, ColorMode.INDEXED)
+  test(app.activeCel.image)
+
+end
diff --git a/tests/scripts/image_iterator.lua b/tests/scripts/image_iterator.lua
new file mode 100644
index 000000000..8b9dcd41b
--- /dev/null
+++ b/tests/scripts/image_iterator.lua
@@ -0,0 +1,72 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local pc = app.pixelColor
+
+-- Iterate pixels
+do
+   local spr = Sprite(2, 2)
+   local image = app.site.image
+   local colors = { pc.rgba(255, 0, 0, 255),
+                    pc.rgba(0, 255, 0, 255),
+                    pc.rgba(255, 0, 255, 255),
+                    pc.rgba(255, 0, 255, 255) }
+   local xy = {
+      { x=0, y=0 },
+      { x=1, y=0 },
+      { x=0, y=1 },
+      { x=1, y=1 } }
+
+   local c = 1
+   for y=0,image.height-1 do
+      for x=0,image.width-1 do
+         image:putPixel(x, y, colors[c])
+         c = c+1
+      end
+   end
+
+   c = 1
+   for y=0,image.height-1 do
+      for x=0,image.width-1 do
+         assert(colors[c] == image:getPixel(x, y))
+         c = c+1
+      end
+   end
+
+   c = 1
+   for it in image:pixels() do
+      assert(colors[c] == it())
+      assert(xy[c].x == it.x)
+      assert(xy[c].y == it.y)
+      c = c+1
+   end
+
+   c = 0
+   for it in image:pixels{x=1, y=0, width=1, height=2} do
+     local i = 1 + it.y*2 + it.x
+     assert(colors[i] == it())
+     assert(xy[i].x == it.x)
+     assert(xy[i].y == it.y)
+     c = c + 1
+   end
+   assert(c == 2)
+
+   -- Iterating outside
+   for it in image:pixels{x=2, y=0, width=2, height=2} do
+     assert(false)
+   end
+
+   c = 1
+   for it in image:pixels() do
+      it(pc.rgba(255, 32*c, 0, 255))
+      c = c+1
+   end
+
+   c = 1
+   for it in image:pixels() do
+      assert(pc.rgba(255, 32*c, 0, 255) == it())
+      c = c+1
+   end
+end
diff --git a/tests/scripts/image_spec.lua b/tests/scripts/image_spec.lua
new file mode 100644
index 000000000..0b8258187
--- /dev/null
+++ b/tests/scripts/image_spec.lua
@@ -0,0 +1,47 @@
+-- Copyright (C) 2018  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local spec = ImageSpec{colorMode=ColorMode.GRAY, width=32, height=64, transparentColor=2}
+  assert(spec.colorMode == ColorMode.GRAY)
+  assert(spec.width == 32)
+  assert(spec.height == 64)
+  assert(spec.transparentColor == 2)
+end
+
+do
+  local sprite = Sprite(32, 64, ColorMode.INDEXED)
+  assert(sprite.width == 32)
+  assert(sprite.height == 64)
+  assert(sprite.colorMode == ColorMode.INDEXED)
+
+  local sprite2 = Sprite(sprite.spec)
+  assert(sprite2.width == 32)
+  assert(sprite2.height == 64)
+  assert(sprite2.colorMode == ColorMode.INDEXED)
+
+  local spec = sprite.spec
+  assert(spec.width == 32)
+  assert(spec.height == 64)
+  assert(spec.colorMode == ColorMode.INDEXED)
+
+  spec.width = 30
+  spec.height = 40
+  spec.colorMode = ColorMode.RGB
+  assert(spec.width == 30)
+  assert(spec.height == 40)
+  assert(spec.colorMode == ColorMode.RGB)
+
+  local image = Image(spec)
+  assert(image.width == 30)
+  assert(image.height == 40)
+  assert(image.colorMode == ColorMode.RGB)
+
+  print(image.spec.width, image.spec.height, image.spec.colorMode)
+  assert(image.spec.width == 30)
+  assert(image.spec.height == 40)
+  assert(image.spec.colorMode == ColorMode.RGB)
+end
diff --git a/tests/scripts/import_sprite_sheet_command.lua b/tests/scripts/import_sprite_sheet_command.lua
new file mode 100644
index 000000000..741d3d5fe
--- /dev/null
+++ b/tests/scripts/import_sprite_sheet_command.lua
@@ -0,0 +1,75 @@
+-- Copyright (C) 2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+do
+  local s = Sprite(8, 4, ColorMode.INDEXED)
+  assert(#s.cels == 1)
+
+  local i = s.cels[1].image
+  array_to_pixels({ 0, 1, 2, 3, 3, 2, 1, 0,
+                    1, 2, 3, 4, 4, 3, 2, 1,
+                    1, 2, 3, 4, 4, 3, 2, 1,
+                    0, 1, 2, 3, 3, 2, 1, 0 }, i)
+
+  app.command.ImportSpriteSheet{
+    ui=false,
+    type=SpriteSheetType.ROWS,
+    frameBounds=Rectangle(0, 0, 4, 4)
+  }
+  assert(#s.cels == 2)
+  expect_img(s.cels[1].image,
+             { 0, 1, 2, 3,
+               1, 2, 3, 4,
+               1, 2, 3, 4,
+               0, 1, 2, 3 })
+  expect_img(s.cels[2].image,
+             { 3, 2, 1, 0,
+               4, 3, 2, 1,
+               4, 3, 2, 1,
+               3, 2, 1, 0 })
+
+  app.undo();
+  app.command.ImportSpriteSheet{
+    ui=false,
+    type=SpriteSheetType.ROWS,
+    frameBounds=Rectangle(0, 0, 2, 3)
+  }
+  assert(#s.cels == 4)
+  expect_img(s.cels[1].image,
+             { 0, 1,
+               1, 2,
+               1, 2 })
+  expect_img(s.cels[2].image,
+             { 2, 3,
+               3, 4,
+               3, 4 })
+  expect_img(s.cels[3].image,
+             { 3, 2,
+               4, 3,
+               4, 3 })
+  expect_img(s.cels[4].image,
+             { 1, 0,
+               2, 1,
+               2, 1 })
+
+
+  app.undo();
+  app.command.ImportSpriteSheet{
+    ui=false,
+    type=SpriteSheetType.ROWS,
+    frameBounds=Rectangle(1, 1, 2, 2),
+    padding=Size(2, 0)
+  }
+  assert(#s.cels == 2)
+  expect_img(s.cels[1].image,
+             { 2, 3,
+               2, 3 })
+  expect_img(s.cels[2].image,
+             { 3, 2,
+               3, 2 })
+
+end
diff --git a/tests/scripts/inks.lua b/tests/scripts/inks.lua
new file mode 100644
index 000000000..91dbfd4f2
--- /dev/null
+++ b/tests/scripts/inks.lua
@@ -0,0 +1,285 @@
+-- Copyright (C) 2020-2022  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+local colorModes = { ColorMode.RGB,
+                     ColorMode.GRAY,
+                     ColorMode.INDEXED }
+
+local pencil = "pencil"
+local pc = app.pixelColor
+
+local function gray(g)
+  return pc.graya(g, 255)
+end
+
+function test_inks(colorMode)
+  -- Test ink over a transparent sprite
+  local s = Sprite(3, 3, colorMode)
+  local p, a, b, c, d
+  if colorMode == ColorMode.GRAY then
+    p = s.palettes[1]
+    a, b, c, d = gray(0), gray(64), gray(128), gray(255)
+  else
+    p = Palette()
+    p:resize(4)
+    p:setColor(0, Color(0, 0, 0))
+    p:setColor(1, Color(64, 64, 64))
+    p:setColor(2, Color(128, 128, 128))
+    p:setColor(3, Color(255, 255, 255))
+    s:setPalette(p)
+
+    a, b, c, d = 0, 1, 2, 3
+    if colorMode == ColorMode.RGB then
+      a = p:getColor(a).rgbaPixel
+      b = p:getColor(b).rgbaPixel
+      c = p:getColor(c).rgbaPixel
+      d = p:getColor(d).rgbaPixel
+    end
+  end
+
+  -- With simple ink opacity doesn't have affect (always the color)
+  local opacities = { 0, 128, 255 }
+  for i = 1,#opacities do
+    expect_img(app.activeImage,
+               { 0, 0, 0,
+                 0, 0, 0,
+                 0, 0, 0 })
+    app.useTool{ tool=pencil, color=d, points={ Point(0, 0), Point(2, 2) },
+                 ink=Ink.SIMPLE, opacity=opacities[i] }
+    expect_img(app.activeImage,
+               { d, 0, 0,
+                 0, d, 0,
+                 0, 0, d })
+    if i < #opacities then app.undo() end
+  end
+
+  -- Check that painting with transparent index (color) on a
+  -- transparent layer (using any value of opacity) with alpha
+  -- compositing doesn't modify pixels
+  for i = 1,#opacities do
+    app.useTool{ tool=pencil, color=0, points={ Point(1, 1) },
+                 ink=Ink.ALPHA_COMPOSITING, opacity=opacities[i] }
+    expect_img(app.activeImage,
+               { d, 0, 0,
+                 0, d, 0,
+                 0, 0, d })
+  end
+
+  -- Convert to background layer
+  app.bgColor = Color{ index=0 }
+  app.command.BackgroundFromLayer()
+
+  app.useTool{ tool=pencil, color=d, points={ Point(0, 1), Point(2, 1) },
+               ink=Ink.ALPHA_COMPOSITING, opacity=64 }
+  expect_img(app.activeImage,
+             { d, a, a,
+               b, d, b,
+               a, a, d })
+
+  app.useTool{ tool=pencil, color=d, points={ Point(0, 1) },
+               ink=Ink.ALPHA_COMPOSITING, opacity=86 }
+  expect_img(app.activeImage,
+             { d, a, a,
+               c, d, b,
+               a, a, d })
+
+  ----------------------------------------------------------------------
+  -- Inks with custom brushes
+
+  function test_custom_brush_inks(brushColorMode)
+    -- Colors in the brush image (ba, bb, bc, bd)
+    local ba, bb, bc, bd
+    if brushColorMode == ColorMode.RGB then
+      ba = Color(0, 0, 0)
+      bb = Color(64, 64, 64)
+      bc = Color(128, 128, 128)
+      bd = Color(255, 255, 255)
+    elseif brushColorMode == ColorMode.GRAY then
+      ba, bb, bc, bd = gray(0), gray(64), gray(128), gray(255)
+    else
+      ba, bb, bc, bd = 0, 1, 2, 3
+    end
+
+    local brushImage = Image(2, 2, brushColorMode)
+    array_to_pixels({ 0, bd,
+                      bc, 0 }, brushImage)
+    local brush = Brush(brushImage)
+
+    -- da, db, dc, dd are the final result after painting the custom
+    -- brush in the sprite
+    local ra, rb, rc, rd
+    if s.colorMode ~= ColorMode.INDEXED and
+       brushColorMode == ColorMode.INDEXED then
+      -- For indexed images we take the index of the brush and use the
+      -- sprite palette, we are not sure if this in the future might
+      -- change, e.g. having the original palette that was used to
+      -- create the brush integrated to the brush itself, in that case
+      -- we should convert the brush index using the same brush
+      -- palette (instead of the sprite palette).
+      --
+      -- TODO check BrushInkProcessingBase comment for more information
+      if s.colorMode == ColorMode.RGB then
+        ra, rb, rc, rd =
+          p:getColor(ba).rgbaPixel,
+          p:getColor(bb).rgbaPixel,
+          p:getColor(bc).rgbaPixel,
+          p:getColor(bd).rgbaPixel
+      else
+        ra, rb, rc, rd =
+          p:getColor(ba).grayPixel,
+          p:getColor(bb).grayPixel,
+          p:getColor(bc).grayPixel,
+          p:getColor(bd).grayPixel
+      end
+    else
+      ra, rb, rc, rd = a, b, c, d
+    end
+
+    array_to_pixels({ a, a, a,
+                      a, a, a,
+                      a, a, a }, app.activeImage)
+
+    -- Simple
+    expect_img(app.activeImage,
+               { a, a, a,
+                 a, a, a,
+                 a, a, a })
+    app.useTool{ tool=pencil, brush=brush, points={ Point(2, 2) },
+                 ink=Ink.SIMPLE }
+    expect_img(app.activeImage,
+               { a, a,  a,
+                 a, a,  rd,
+                 a, rc, a })
+
+    -- Alpha Compositing
+    app.useTool{ tool=pencil, brush=brush, points={ Point(1, 1) },
+                 ink=Ink.ALPHA_COMPOSITING, opacity=255 }
+    expect_img(app.activeImage,
+               {  a, rd,  a,
+                 rc,  a, rd,
+                  a, rc,  a })
+
+    local qc, qd
+    if s.colorMode == ColorMode.GRAY and
+       brushColorMode == ColorMode.INDEXED then
+      qc = gray(pc.grayaV(rc)/2)
+      qd = gray(pc.grayaV(rd)/2)
+    else
+      qc, qd = rb, rc
+    end
+
+    app.useTool{ tool=pencil, brush=brush, points={ Point(1, 2) },
+                 ink=Ink.ALPHA_COMPOSITING, opacity=128 }
+    expect_img(app.activeImage,
+               {  a, rd,  a,
+                 rc, qd, rd,
+                 qc, rc,  a })
+
+    -- TODO test Lock Alpha, Copy Color+Alpha, Shading...
+  end
+
+  for j = 1,#colorModes do
+    test_custom_brush_inks(colorModes[j])
+  end
+end
+
+function test_alpha_compositing_on_indexed_with_full_opacity_and_repeated_colors_in_palette()
+  local s = Sprite(1, 1, ColorMode.INDEXED)
+  local p = Palette()
+  p:resize(5)
+  p:setColor(0, Color(0, 0, 0))
+  p:setColor(1, Color(64, 64, 64))
+  p:setColor(2, Color(128, 128, 128))
+  p:setColor(3, Color(128, 128, 128))
+  p:setColor(4, Color(255, 255, 255))
+  s:setPalette(p)
+
+  local inks = { Ink.SIMPLE, Ink.ALPHA_COMPOSITING }
+
+  -- k=1 -> transparent layer
+  -- k=2 -> background layer
+  for k=1,2 do
+    if k == 2 then app.command.BackgroundFromLayer() end
+    --  i=1 -> simple ink
+    --  i=2 -> alpha compositing ink
+    for i = 1,2 do
+      -- j=color index
+      for j = 0,4 do
+        expect_img(app.activeImage, { 0 })
+        app.useTool{ tool="pencil", color=j, points={ Point(0, 0) },
+                     ink=inks[i], opacity=255 }
+        expect_img(app.activeImage, { j })
+        app.undo()
+      end
+    end
+  end
+end
+
+for i = 1,#colorModes do
+  test_inks(colorModes[i])
+end
+test_alpha_compositing_on_indexed_with_full_opacity_and_repeated_colors_in_palette()
+
+----------------------------------------------------------------------
+-- Test painting with transparent color on indexed
+----------------------------------------------------------------------
+
+do
+  local s = Sprite(2, 2, ColorMode.INDEXED)
+  s.transparentColor = 0
+  app.bgColor = 0
+  app.command.BackgroundFromLayer()
+  assert(app.activeLayer.isBackground)
+  expect_img(app.activeImage, { 0, 0,
+                                0, 0 })
+
+  app.useTool{ tool="pencil", color=Color{r=0,g=0,b=0},
+               points={ Point(0, 0) },
+               ink=Ink.SIMPLE }
+  expect_img(app.activeImage, { 0, 0,
+                                0, 0 })
+
+  -- Test that painting in the background layer with transparent color
+  -- with alpha compositing and all opacity=255, will use the transparent
+  -- index anyway. Reported here: https://github.com/aseprite/aseprite/issues/3047
+  app.useTool{ tool="pencil", color=0,
+               points={ Point(0, 0) },
+               ink=Ink.ALPHA_COMPOSITING,
+               opacity=255 }
+  expect_img(app.activeImage, { 0, 0,
+                                0, 0 })
+
+  -- Other cases should keep working
+  local p = s.palettes[1]
+
+  -- palette with only 3 colors: white, gray (50%), black
+  p:setColor(0, Color{ r=255, g=255, b=255 })
+  p:setColor(1, Color{ r=128, g=128, b=128 })
+  p:setColor(2, Color{ r=0, g=0, b=0 })
+  app.useTool{ tool="paint_bucket", color=2,
+               points={ Point(0, 0) },
+               ink=Ink.SIMPLE }
+  expect_img(app.activeImage, { 2, 2,
+                                2, 2 })
+
+  -- White over black w/opacity=50% => gray
+  app.useTool{ tool="pencil", color=0,
+               points={ Point(0, 0) },
+               ink=Ink.ALPHA_COMPOSITING,
+               opacity=128 }
+  expect_img(app.activeImage, { 1, 2,
+                                2, 2 })
+
+  -- White over gray w/opacity=51% => white
+  app.useTool{ tool="pencil", color=0,
+               points={ Point(0, 0) },
+               ink=Ink.ALPHA_COMPOSITING,
+               opacity=129 }
+  expect_img(app.activeImage, { 0, 2,
+                                2, 2 })
+
+end
diff --git a/tests/scripts/layer.lua b/tests/scripts/layer.lua
new file mode 100644
index 000000000..6eb6ec083
--- /dev/null
+++ b/tests/scripts/layer.lua
@@ -0,0 +1,22 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local s = Sprite(32, 64)
+  local l = s.layers[1]
+  assert(l.parent == s)
+  assert(l.opacity == 255)
+  assert(l.blendMode == BlendMode.NORMAL)
+
+  l.name = "My Layer"
+  l.opacity = 128
+  l.blendMode = BlendMode.MULTIPLY
+  assert(l.name == "My Layer")
+  assert(l.opacity == 128)
+  assert(l.blendMode == BlendMode.MULTIPLY)
+
+  l.data = "Data"
+  assert(l.data == "Data")
+end
diff --git a/tests/scripts/layers.lua b/tests/scripts/layers.lua
new file mode 100644
index 000000000..a8e16dffc
--- /dev/null
+++ b/tests/scripts/layers.lua
@@ -0,0 +1,215 @@
+-- Copyright (C) 2019-2022  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local s = Sprite(32, 32)
+  assert(#s.layers == 1)
+
+  local a = s.layers[1]
+  local b = s:newLayer()
+  local c = s:newLayer()
+
+  assert(#s.layers == 3)
+  assert(s.layers[1] == a)
+  assert(s.layers[2] == b)
+  assert(s.layers[3] == c)
+
+  local i = 1
+  for k,v in ipairs(s.layers) do
+    assert(i == k)
+    assert(v == s.layers[k])
+    i = i+1
+  end
+
+  s:deleteLayer(b)
+  assert(#s.layers == 2)
+  assert(s.layers[1] == a)
+  assert(s.layers[2] == c)
+end
+
+-- Test groups
+
+do
+  local s = Sprite(32, 64)
+  local l = s.layers[1]
+  assert(#s.layers == 1)
+  local g = s:newGroup()
+  assert(#s.layers == 2)
+  assert(l.parent == s)
+  assert(g.parent == s)
+  assert(s.layers[1] == l)
+  assert(s.layers[2] == g)
+
+  l.parent = g
+  assert(g.parent == s)
+  assert(l.parent == g)
+
+  assert(#s.layers == 1)
+  assert(s.layers[1] == g)
+  assert(#s.layers[1].layers == 1)
+  assert(s.layers[1].layers[1] == l)
+end
+
+do
+  local s = Sprite(4, 4)
+  -- 4 layers
+  local a = s.layers[1]    a.name = "a"
+  local b = s:newLayer()   b.name = "b"
+  local c = s:newLayer()   c.name = "c"
+  local d = s:newLayer()   d.name = "d"
+  -- 3 groups
+  local e = s:newGroup()   e.name = "e"
+  local f = s:newGroup()   f.name = "f"
+  local g = s:newGroup()   g.name = "g"
+
+  e.parent = f
+  a.parent = f
+  b.parent = f
+  c.parent = g
+  d.parent = g
+
+  assert(#s.layers == 2)
+  assert(s.layers[1] == f)
+  assert(s.layers[2] == g)
+  assert(s.layers["f"] == f)
+  assert(s.layers["g"] == g)
+  assert(f.stackIndex == 1)
+  assert(g.stackIndex == 2)
+
+  assert(#f.layers == 3)
+  assert(f.layers[1] == e)
+  assert(f.layers[2] == a)
+  assert(f.layers[3] == b)
+  assert(f.layers["e"] == e)
+  assert(f.layers["a"] == a)
+  assert(f.layers["b"] == b)
+  assert(e.stackIndex == 1)
+  assert(a.stackIndex == 2)
+  assert(b.stackIndex == 3)
+
+  assert(#g.layers == 2)
+  assert(g.layers[1] == c)
+  assert(g.layers[2] == d)
+  assert(g.layers["c"] == c)
+  assert(g.layers["d"] == d)
+  assert(c.stackIndex == 1)
+  assert(d.stackIndex == 2)
+
+  d.stackIndex = 1
+  assert(d.stackIndex == 1)
+  assert(c.stackIndex == 2)
+
+  d.stackIndex = 2
+  assert(c.stackIndex == 1)
+  assert(d.stackIndex == 2)
+
+  c.stackIndex = 2
+  assert(d.stackIndex == 1)
+  assert(c.stackIndex == 2)
+end
+
+-- Test possible bugs with stackIndex
+do
+  local s = Sprite(4, 4)
+  local a = s.layers[1]    a.name = "a"
+  local b = s:newLayer()   b.name = "b"
+  local c = s:newLayer()   c.name = "c"
+  local d = s:newLayer()   d.name = "d"
+  assert(d.stackIndex == 4)
+  assert(s.layers[4].name == "d")
+
+  d.stackIndex = d.stackIndex+1
+  assert(d.stackIndex == 4)
+  assert(s.layers[4].name == "d")
+
+  -- Go down in the stack
+  d.stackIndex = d.stackIndex-1
+  assert(s.layers[3].name == "d")
+
+  d.stackIndex = d.stackIndex-1
+  assert(s.layers[2].name == "d")
+
+  -- Without change
+  d.stackIndex = d.stackIndex
+  assert(s.layers[2].name == "d")
+
+  -- Go up
+  d.stackIndex = d.stackIndex+1
+  assert(d.stackIndex == 3)
+  assert(s.layers[3].name == "d")
+
+  d.stackIndex = d.stackIndex+1
+  assert(d.stackIndex == 4)
+  assert(s.layers[4].name == "d")
+
+  -- Go specific stack indexes
+  for i=1,4 do
+    d.stackIndex = i
+    assert(d.stackIndex == i)
+    assert(s.layers[i].name == "d")
+  end
+end
+
+-- Test crash because ActiveSiteHandler::onBeforeRemoveLayer() didn't
+-- update the selected range of layers correctly (i.e. removing
+-- deleted layer from the selected layers in the active range).
+do
+  local s = Sprite(4, 4)
+  local a  = s:newGroup()   a.name = "a"
+  local b  = s:newGroup()   b.name = "b"
+  local c  = s:newGroup()   c.name = "c"
+  local ca = s:newGroup()  ca.name = "ca"
+  local cb = s:newGroup()  cb.name = "cb"
+  local d  = s:newGroup()   d.name = "d"
+
+  d.parent = ca
+  ca.parent = c
+  cb.parent = c
+  c.parent = b
+  b.parent = a
+
+  assert(#a.layers == 1)
+  assert(#c.layers == 2)
+
+  app.range.layers = { b }
+  app.command.RemoveLayer()
+  assert(#a.layers == 0)
+  app.undo()
+  assert(#a.layers == 1)
+  assert(#c.layers == 2)
+
+  -- Crash selecting a layer that was removed and then brought back to
+  -- life with "undo"
+  app.range.layers = { b }
+end
+
+-- Test layer name bug when iterating over layers where names given to
+-- some layers are integers and also are valid ranges/indexes in the
+-- list of layers
+do
+  local layerNames = { "2", "4", "Non-integer", "1" }
+  local s = Sprite(4, 4)
+  local layer1 = s.layers[1]   layer1.name = layerNames[1]
+  local layer2 = s:newLayer()  layer2.name = layerNames[2]
+  local layer3 = s:newLayer()  layer3.name = layerNames[3]
+  local layer4 = s:newLayer()  layer4.name = layerNames[4]
+
+  local i = 1
+  for index, layer in ipairs(app.activeSprite.layers) do
+    assert(index == i)
+    assert(layer.name == layerNames[i])
+    i = i + 1
+  end
+end
+
+-- Compare layers vs sprites (just return false)
+
+do
+  local s = Sprite(2, 2)
+  assert(s.layers[1].parent == s)
+  assert(s.layers[1] ~= s) -- Uses Layer_eq() to compare
+  assert(s ~= s.layers[1]) -- Uses Sprite_eq() to compare
+end
diff --git a/tests/scripts/math.lua b/tests/scripts/math.lua
new file mode 100644
index 000000000..b08b2605a
--- /dev/null
+++ b/tests/scripts/math.lua
@@ -0,0 +1,10 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+assert(100 == math.abs(-100))
+assert(100 == math.min(100, 200, 300))
+assert(300 == math.max(100, 200, 300))
+assert(50 == math.fmod(250, 100))
+assert(3141 == math.floor(1000*math.pi))
diff --git a/tests/scripts/merge_down_bugs.lua b/tests/scripts/merge_down_bugs.lua
new file mode 100644
index 000000000..a98cfdb97
--- /dev/null
+++ b/tests/scripts/merge_down_bugs.lua
@@ -0,0 +1,27 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local red = Color{ r=255, g=0, b=0 }
+local blue = Color{ r=0, g=0, b=255 }
+
+-- Reproduces the bug reported in https://community.aseprite.org/t/2894
+do
+  local s = Sprite(32, 32)
+  local a = s.layers[1]
+  app.useTool{ color=red, layer=a, points={ Point(2, 2) }}
+
+  local b = s:newLayer()
+  app.useTool{ color=blue, layer=b, points={ Point(1, 1) }}
+
+  a.isContinuous = true
+  b.isContinuous = true
+
+  app.command.NewFrame()
+  app.activeLayer = b
+  app.command.MergeDownLayer()
+
+  assert(#s.cels == 2)
+  assert(s.cels[1].image:isEqual(s.cels[2].image))
+end
diff --git a/tests/scripts/os.lua b/tests/scripts/os.lua
new file mode 100644
index 000000000..f18060237
--- /dev/null
+++ b/tests/scripts/os.lua
@@ -0,0 +1,14 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+assert("" ~= os.getenv("PATH"))
+print("PATH", os.getenv("PATH"))
+
+local start_clock = os.clock()
+print("Start ", start_clock)
+
+local end_clock = os.clock()
+print("End ", end_clock, " Elapsed ", end_clock - start_clock)
+assert(start_clock < end_clock)
diff --git a/tests/scripts/paint_bucket.lua b/tests/scripts/paint_bucket.lua
new file mode 100644
index 000000000..52276f617
--- /dev/null
+++ b/tests/scripts/paint_bucket.lua
@@ -0,0 +1,55 @@
+-- Copyright (C) 2020-2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+app.activeTool = 'paint_bucket'
+assert(app.activeTool.id == 'paint_bucket')
+assert(app.activeBrush.type == BrushType.CIRCLE)
+assert(app.activeBrush.size == 1)
+assert(app.activeBrush.angle == 0)
+assert(app.preferences.tool('paint_bucket').floodfill.pixel_connectivity == 0)
+
+local function test_paint_bucket(colorMode, a, b, c)
+  local spr = Sprite(4, 4, colorMode)
+  local img = app.activeImage
+
+  array_to_pixels({ a, a, a, a,
+                    a, b, b, a,
+                    a, a, b, a,
+                    a, a, a, b, }, img)
+
+  app.useTool{ points={Point(0, 0)}, color=b }
+  expect_img(img, { b, b, b, b,
+                    b, b, b, b,
+                    b, b, b, b,
+                    b, b, b, b, })
+
+  app.undo()
+  -- FOUR_CONNECTED=0
+  app.preferences.tool('paint_bucket').floodfill.pixel_connectivity = 0
+  assert(app.preferences.tool('paint_bucket').floodfill.pixel_connectivity == 0)
+  app.useTool{ points={Point(1, 1)}, color=c }
+  expect_img(img, { a, a, a, a,
+                    a, c, c, a,
+                    a, a, c, a,
+                    a, a, a, b, })
+
+  app.undo()
+  -- EIGHT_CONNECTED=1
+  app.preferences.tool('paint_bucket').floodfill.pixel_connectivity = 1
+  assert(app.preferences.tool('paint_bucket').floodfill.pixel_connectivity == 1)
+  app.useTool{ points={Point(1, 1)}, color=c }
+  expect_img(img, { a, a, a, a,
+                    a, c, c, a,
+                    a, a, c, a,
+                    a, a, a, c, })
+end
+
+local rgba = app.pixelColor.rgba
+local gray = app.pixelColor.graya
+test_paint_bucket(ColorMode.RGB, rgba(0, 0, 0), rgba(128, 128, 128), rgba(255, 255, 255))
+test_paint_bucket(ColorMode.GRAYSCALE, gray(0), gray(128), gray(255))
+test_paint_bucket(ColorMode.INDEXED, 1, 2, 3)
diff --git a/tests/scripts/palette.lua b/tests/scripts/palette.lua
new file mode 100644
index 000000000..6a22abfc1
--- /dev/null
+++ b/tests/scripts/palette.lua
@@ -0,0 +1,87 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local p = Palette()
+  assert(#p == 256)
+  for i = 0,#p-1 do
+    assert(p:getColor(i) == Color(0, 0, 0))
+  end
+end
+
+do
+  local p = Palette(32)
+  assert(#p == 32)
+  for i = 0,#p-1 do
+    assert(p:getColor(i) == Color(0, 0, 0))
+  end
+
+  p:resize(4)
+  assert(#p == 4)
+  p:setColor(0, Color(255, 8, 32))
+  p:setColor(1, Color(250, 4, 30))
+  p:setColor(2, Color(240, 3, 20))
+  p:setColor(3, Color(210, 2, 10))
+  assert(p:getColor(0) == Color(255, 8, 32))
+  assert(p:getColor(1) == Color(250, 4, 30))
+  assert(p:getColor(2) == Color(240, 3, 20))
+  assert(p:getColor(3) == Color(210, 2, 10))
+
+  -- Check alpha
+  local c = Color{red=100, green=50, blue=10, alpha=128}
+  p:setColor(3, c)
+  assert(p:getColor(3) == c)
+  assert(p:getColor(3).alpha == 128)
+end
+
+-- Load/save
+do
+  local p = Palette{ fromFile="sprites/abcd.aseprite" }
+  assert(#p == 5)
+  assert(p:getColor(0) == Color(0, 0, 0))
+  assert(p:getColor(1) == Color(25, 0, 255))
+  assert(p:getColor(2) == Color(255, 0, 0))
+  assert(p:getColor(3) == Color(255, 255, 0))
+  assert(p:getColor(4) == Color(0, 128, 0))
+
+  p:saveAs("_test_.gpl")
+
+  local q = Palette{ fromFile="_test_.gpl" }
+  assert(#p == #q)
+  for i=0,#q-1 do
+    assert(p:getColor(i) == q:getColor(i))
+  end
+end
+
+-- Default palette and resources
+do
+  local db16 = Palette{ fromResource="DB16" }
+  local db32 = Palette{ fromResource="DB32" }
+
+  assert(#db16 == 16)
+  assert(#db32 == 32)
+  assert(db32:getColor(0) == Color(0, 0, 0))
+  assert(db32:getColor(31) == Color(138, 111, 48))
+
+  assert(app.defaultPalette == db32)
+
+  app.defaultPalette = db16
+  assert(app.defaultPalette == db16)
+
+  -- Default sprite palette is completely black
+  -- TODO should we use the app.defaultPalette as the default palette?
+  local spr = Sprite(32, 32, ColorMode.INDEXED)
+  local sprPal = spr.palettes[1];
+  assert(#sprPal == 256)
+  assert(sprPal ~= db16)
+  assert(sprPal ~= db32)
+  for i=0,255 do
+    assert(sprPal:getColor(i) == Color(0, 0,0))
+  end
+
+  spr:setPalette(db32)
+  assert(sprPal == db32)
+end
diff --git a/tests/scripts/pixel_perfect.lua b/tests/scripts/pixel_perfect.lua
new file mode 100644
index 000000000..391dd8644
--- /dev/null
+++ b/tests/scripts/pixel_perfect.lua
@@ -0,0 +1,361 @@
+-- Copyright (C) 2019-2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+local spr = Sprite(6, 6)
+local cel = spr.cels[1]
+
+-- Point size 1px, solid color, no symmetry, no tiled mode
+do
+  local title = '1px, solid, no symmetry, no tiled'
+  local red = Color{ r=255, g=0, b=0 }
+  local r = red.rgbaPixel
+  local pixel=Brush{ size=1, type=BrushType.CIRCLE }
+  local testData = {
+    {
+      id='1 - ' .. title .. ': right then down',
+      points={ Point(2, 2), Point(3, 2), Point(3, 3) },
+      expected={ r, 0,
+                 0, r }
+    },
+    {
+      id='2 - ' .. title .. ': down then right',
+      points={ Point(2, 2), Point(2, 3), Point(3, 3) },
+      expected={ r, 0,
+                 0, r }
+    },
+    {
+      id='3 - ' .. title .. ': left then up',
+      points={ Point(2, 2), Point(1, 2), Point(1, 1) },
+      expected={ r, 0,
+                 0, r }
+    },
+    {
+      id='4 - ' .. title .. ': up then left',
+      points={ Point(2, 2), Point(2, 1), Point(1, 1) },
+      expected={ r, 0,
+                 0, r }
+    }
+  }
+
+  for i,v in ipairs(testData) do
+    app.useTool{
+      tool='pencil',
+      freehandAlgorithm=1,
+      brush=pixel,
+      color=red,
+      points=v.points}
+    expect_img_msg(cel.image, v.expected, '\nTest \'' .. v.id .. '\' failed')
+    cel.image:clear(0)
+  end
+end
+
+-- Point size 2px, translucent color, no symmetry, no tiled mode
+do
+  local title = '2px, translucent, no symmetry, no tiled'
+  local red = Color{ r=255, g=0, b=0, a=127 }
+  local r = red.rgbaPixel
+  local square=Brush{ size=2, type=BrushType.SQUARE }
+  local testData = {
+    {
+      id='1 - ' .. title .. ': right then down',
+      points={ Point(2, 2), Point(3, 2), Point(3, 3) },
+      expected={ r, r, 0,
+                 r, r, r,
+                 0, r, r }
+    },
+    {
+      id='2 - ' .. title .. ': down then right',
+      points={ Point(2, 2), Point(2, 3), Point(3, 3) },
+      expected={ r, r, 0,
+                 r, r, r,
+                 0, r, r }
+    },
+    {
+      id='3 - ' .. title .. ': left then up',
+      points={ Point(2, 2), Point(1, 2), Point(1, 1) },
+      expected={ r, r, 0,
+                 r, r, r,
+                 0, r, r }
+    },
+    {
+      id='4 - ' .. title .. ': up then left',
+      points={ Point(2, 2), Point(2, 1), Point(1, 1) },
+      expected={ r, r, 0,
+                 r, r, r,
+                 0, r, r }
+    }
+  }
+
+  for i,v in ipairs(testData) do
+    app.useTool{
+      tool='pencil',
+      freehandAlgorithm=1,
+      brush=square,
+      color=red,
+      points=v.points}
+    expect_img_msg(cel.image, v.expected, '\nTest \'' .. v.id .. '\' failed')
+    cel.image:clear(0)
+  end
+end
+
+-- Point size 2px, translucent color, symmetry, no tiled mode
+do
+  local pref = app.preferences
+  local docPref = pref.document(spr)
+  pref.symmetry_mode.enabled = true
+  docPref.symmetry.mode   = 3
+  docPref.symmetry.x_axis = 3
+  docPref.symmetry.y_axis = 3
+
+  local title = '2px, translucent, symmetry on, no tiled'
+  local red = Color{ r=255, g=0, b=0, a=127 }
+  local r = red.rgbaPixel
+  local square=Brush{ size=2, type=BrushType.SQUARE }
+  local testData = {
+    {
+      id='1 - ' .. title .. ': right then down',
+      points={ Point(1, 1), Point(2, 1), Point(2, 2) },
+      expected={ r, r, 0, 0, r, r,
+                 r, r, r, r, r, r,
+                 0, r, r, r, r, 0,
+                 0, r, r, r, r, 0,
+                 r, r, r, r, r, r,
+                 r, r, 0, 0, r, r }
+    },
+    {
+      id='2 - ' .. title .. ': down then right',
+      points={ Point(1, 1), Point(1, 2), Point(2, 2) },
+      expected={ r, r, 0, 0, r, r,
+                 r, r, r, r, r, r,
+                 0, r, r, r, r, 0,
+                 0, r, r, r, r, 0,
+                 r, r, r, r, r, r,
+                 r, r, 0, 0, r, r }
+    },
+    {
+      id='3 - ' .. title .. ': left then up',
+      points={ Point(2, 2), Point(1, 2), Point(1, 1) },
+      expected={ r, r, 0, 0, r, r,
+                 r, r, r, r, r, r,
+                 0, r, r, r, r, 0,
+                 0, r, r, r, r, 0,
+                 r, r, r, r, r, r,
+                 r, r, 0, 0, r, r }
+    },
+    {
+      id='4 - ' .. title .. ': up then left',
+      points={ Point(2, 2), Point(2, 1), Point(1, 1) },
+      expected={ r, r, 0, 0, r, r,
+                 r, r, r, r, r, r,
+                 0, r, r, r, r, 0,
+                 0, r, r, r, r, 0,
+                 r, r, r, r, r, r,
+                 r, r, 0, 0, r, r }
+    }
+  }
+
+  for i,v in ipairs(testData) do
+    app.useTool{
+      tool='pencil',
+      freehandAlgorithm=1,
+      brush=square,
+      color=red,
+      points=v.points}
+    expect_img_msg(cel.image, v.expected, '\nTest \'' .. v.id .. '\' failed')
+    cel.image:clear(0)
+  end
+end
+
+-- Point size 2px, translucent color, no symmetry, tiled mode on
+do
+  local pref = app.preferences
+  local docPref = pref.document(spr)
+  pref.symmetry_mode.enabled = false
+  docPref.tiled.mode = 3
+
+  local title = '2px, translucent, no symmetry, tiled'
+  local red = Color{ r=255, g=0, b=0, a=127 }
+  local r = red.rgbaPixel
+  local square=Brush{ size=2, type=BrushType.SQUARE }
+  local testData = {
+    -- Top left corner
+    {
+      id='1 - ' .. title .. ': on top left corner, right then down',
+      points={ Point(0, 0), Point(1, 0), Point(1, 1) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='2 - ' .. title .. ': on top left corner, down then right',
+      points={ Point(0, 0), Point(0, 1), Point(1, 1) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='3 - ' .. title .. ': on top left corner, left then up',
+      points={ Point(0, 0), Point(-1, 0), Point(-1, -1) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    {
+      id='4 - ' .. title .. ': on top left corner, up then left',
+      points={ Point(0, 0), Point(0, -1), Point(-1, -1) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    -- Top right corner
+    {
+      id='5 - ' .. title .. ': on top right corner, right then down',
+      points={ Point(6, 0), Point(7, 0), Point(7, 1) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='6 - ' .. title .. ': on top right corner, down then right',
+      points={ Point(6, 0), Point(6, 1), Point(7, 1) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='7 - ' .. title .. ': on top right corner, left then up',
+      points={ Point(6, 0), Point(5, 0), Point(5, -1) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    {
+      id='8 - ' .. title .. ': on top right corner, up then left',
+      points={ Point(6, 0), Point(5, 0), Point(5, -1) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    -- Bottom left corner
+    {
+      id='9 - ' .. title .. ': on bottom left corner, right then down',
+      points={ Point(0, 6), Point(1, 6), Point(1, 7) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='10 - ' .. title .. ': on bottom left corner, down then right',
+      points={ Point(0, 6), Point(0, 7), Point(1, 7) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='11 - ' .. title .. ': on bottom left corner, left then up',
+      points={ Point(0, 6), Point(-1, 6), Point(-1, 5) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    {
+      id='12 - ' .. title .. ': on bottom left corner, up then left',
+      points={ Point(0, 6), Point(0, 5), Point(-1, 5) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    -- Botomm right corner
+    {
+      id='13 - ' .. title .. ': on bottom right corner, right then down',
+      points={ Point(6, 6), Point(7, 6), Point(7, 7) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='14 - ' .. title .. ': on bottom right corner, down then right',
+      points={ Point(6, 6), Point(6, 7), Point(7, 7) },
+      expected={ r, r, 0, 0, 0, r,
+                 r, r, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 r, 0, 0, 0, 0, r }
+    },
+    {
+      id='15 - ' .. title .. ': on bottom right corner, left then up',
+      points={ Point(6, 6), Point(5, 6), Point(5, 5) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+    {
+      id='16 - ' .. title .. ': on bottom right corner, up then left',
+      points={ Point(6, 6), Point(6, 5), Point(5, 5) },
+      expected={ r, 0, 0, 0, 0, r,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, 0, 0,
+                 0, 0, 0, 0, r, r,
+                 r, 0, 0, 0, r, r }
+    },
+  }
+
+  for i,v in ipairs(testData) do
+    app.useTool{
+      tool='pencil',
+      freehandAlgorithm=1,
+      brush=square,
+      color=red,
+      points=v.points}
+    expect_img_msg(cel.image, v.expected, '\nTest \'' .. v.id .. '\' failed')
+    cel.image:clear(0)
+  end
+end
diff --git a/tests/scripts/point.lua b/tests/scripts/point.lua
new file mode 100644
index 000000000..88add18ae
--- /dev/null
+++ b/tests/scripts/point.lua
@@ -0,0 +1,75 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local pt = Point()
+assert(pt.x == 0)
+assert(pt.y == 0)
+
+pt = Point(1, 2)
+assert(pt.x == 1)
+assert(pt.y == 2)
+assert("Point{ x=1, y=2 }" == tostring(pt))
+
+local pt2 = Point(pt)
+assert(pt2.x == 1)
+assert(pt2.y == 2)
+
+pt.x = 5
+pt.y = 6
+assert(pt.x == 5)
+assert(pt.y == 6)
+
+pt = Point{x=10, y=20}
+assert(pt.x == 10)
+assert(pt.y == 20)
+
+pt = Point{45, 25}
+assert(pt.x == 45)
+assert(pt.y == 25)
+
+pt = -pt
+assert(pt.x == -45)
+assert(pt.y == -25)
+
+-- add/sub/mul/div/mod/pow/idiv
+
+pt = Point(1, 2) + 4
+pt2 = 4 + Point(1, 2)
+assert(pt.x == 5)
+assert(pt.y == 6)
+assert(pt == pt2)
+
+pt = Point(1, 2) + Point(3, 4)
+assert(pt.x == 4)
+assert(pt.y == 6)
+
+pt = Point(3, 4) - 1
+assert(pt.x == 2)
+assert(pt.y == 3)
+
+pt = Point(1, 5) - Point(3, 2)
+assert(pt.x == -2)
+assert(pt.y == 3)
+
+pt = Point(6, 10) * 2
+assert(pt.x == 12)
+assert(pt.y == 20)
+
+pt = Point(6, 10) / 2
+assert(pt.x == 3)
+assert(pt.y == 5)
+
+pt = Point(10, 5) % 2
+assert(pt.x == 0)
+assert(pt.y == 1)
+
+pt = Point(2, 5) ^ 2
+assert(pt.x == 4)
+assert(pt.y == 25)
+
+pt = Point(31, 10) // 3
+assert(pt.x == 10)
+assert(pt.y == 3)
diff --git a/tests/scripts/print_on_gc.lua b/tests/scripts/print_on_gc.lua
new file mode 100644
index 000000000..f39c50fce
--- /dev/null
+++ b/tests/scripts/print_on_gc.lua
@@ -0,0 +1,10 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+-- Create global variable which will be GC'd on lua_close()
+a = { }
+
+-- Call print() on __gc, in previous version this produced a crash at exit
+setmetatable(a, { __gc=function() print('gc') end })
diff --git a/tests/scripts/range.lua b/tests/scripts/range.lua
new file mode 100644
index 000000000..3128e8e3c
--- /dev/null
+++ b/tests/scripts/range.lua
@@ -0,0 +1,118 @@
+-- Copyright (C) 2019-2020  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  -- Three layers
+  local s = Sprite(32, 32)
+  assert(#s.layers == 1)
+
+  app.activeCel = s.cels[1]
+
+  local r = app.range
+  assert(#r.layers == 1)
+  assert(#r.frames == 1)
+  assert(#r.cels == 1)
+  assert(r.layers[1] == s.layers[1])
+  assert(r.frames[1] == s.frames[1])
+  assert(r.cels[1] == s.cels[1])
+
+  s:newLayer()
+  assert(#s.layers == 2)
+
+  local r = app.range
+  assert(#r.layers == 1)
+  assert(#r.frames == 1)
+  assert(#r.cels == 0)
+  assert(r.layers[1] == s.layers[2])
+  assert(r.frames[1] == s.frames[1])
+end
+
+-- Test app.range.colors
+do
+  assert(#app.range.colors == 0)
+  app.range.colors = { 2 }
+  assert(#app.range.colors == 1)
+  assert(app.range.colors[1] == 2)
+  app.range.colors = { 1, 4 }
+  assert(#app.range.colors == 2)
+  assert(app.range.colors[1] == 1)
+  assert(app.range.colors[2] == 4)
+  app.range.colors = { 5, 2, 10, 8, 0 }
+  assert(#app.range.colors == 5)
+  -- app.range.colors are always sorted by color index
+  assert(app.range.colors[1] == 0)
+  assert(app.range.colors[2] == 2)
+  assert(app.range.colors[3] == 5)
+  assert(app.range.colors[4] == 8)
+  assert(app.range.colors[5] == 10)
+  assert(app.range:containsColor(0))
+  assert(not app.range:containsColor(1))
+  assert(app.range:containsColor(2))
+  assert(app.range:containsColor(5))
+  assert(app.range:containsColor(8))
+  assert(app.range:containsColor(10))
+end
+
+-- Test setters
+do
+  local spr = Sprite(32, 32)
+  local lay1 = spr.layers[1]
+  local r = app.range
+  assert(r.type == RangeType.EMPTY)
+  assert(#r.layers == 1)
+  assert(#r.frames == 1)
+  assert(r.layers[1] == lay1)
+  assert(r.frames[1].frameNumber == 1)
+
+  local lay2 = spr:newLayer()
+  r = app.range
+  assert(r.type == RangeType.EMPTY)
+  assert(#r.layers == 1)
+  assert(#r.frames == 1)
+  assert(r.layers[1] == lay2)
+  assert(r.frames[1].frameNumber == 1)
+
+  r.layers = { lay1, lay2 }
+  assert(r.type == RangeType.LAYERS)
+  assert(#r.layers == 2)
+  assert(#r.frames == 1)
+  assert(r.layers[1] == lay1)
+  assert(r.layers[2] == lay2)
+  assert(r.frames[1].frameNumber == 1)
+
+  spr:newFrame()
+  spr:newFrame()
+  r.frames = { 1, 3 }
+  assert(r.type == RangeType.FRAMES)
+  assert(#r.layers == 2)
+  assert(#r.frames == 2)
+  assert(r.layers[1] == lay1)
+  assert(r.layers[2] == lay2)
+  assert(r.frames[1].frameNumber == 1)
+  assert(r.frames[2].frameNumber == 3)
+
+  r.layers = { lay2 }
+  assert(r.type == RangeType.LAYERS)
+  assert(#r.layers == 1)
+  assert(#r.frames == 2)
+  assert(r.layers[1] == lay2)
+  assert(r.frames[1].frameNumber == 1)
+  assert(r.frames[2].frameNumber == 3)
+
+  -- Clear range
+  r:clear()
+  assert(r.type == RangeType.EMPTY)
+  assert(#r.layers == 1)
+  assert(#r.frames == 1)
+  assert(r.layers[1] == app.activeLayer)
+  assert(r.frames[1] == app.activeFrame)
+
+  -- Check that Range:clear() reset the selected colors
+  r.colors = { 2 }
+  assert(#r.colors == 1)
+  assert(r.colors[1] == 2)
+  r:clear()
+  assert(#r.colors == 0)
+end
diff --git a/tests/scripts/rectangle.lua b/tests/scripts/rectangle.lua
new file mode 100644
index 000000000..a1c2f2c20
--- /dev/null
+++ b/tests/scripts/rectangle.lua
@@ -0,0 +1,72 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local rc = Rectangle()
+assert(rc.x == 0)
+assert(rc.y == 0)
+assert(rc.width == 0)
+assert(rc.height == 0)
+assert(rc.isEmpty)
+
+rc = Rectangle(1, 2, 3, 4)
+assert(rc.x == 1)
+assert(rc.y == 2)
+assert(rc.width == 3)
+assert(rc.height == 4)
+assert(not rc.isEmpty)
+assert("Rectangle{ x=1, y=2, width=3, height=4 }" == tostring(rc))
+
+local rc2 = Rectangle(rc)
+assert(rc2.x == 1)
+assert(rc2.y == 2)
+assert(rc2.width == 3)
+assert(rc2.height == 4)
+
+rc.x = 5;
+rc.y = 6;
+rc.width = 7;
+rc.height = 8;
+assert(rc.x == 5)
+assert(rc.y == 6)
+assert(rc.width == 7)
+assert(rc.height == 8)
+
+rc = Rectangle{x=2, y=3, width=4, height=5}
+assert(rc.x == 2)
+assert(rc.y == 3)
+assert(rc.width == 4)
+assert(rc.height == 5)
+
+rc = Rectangle{6, 7, 8, 9}
+assert(rc.x == 6)
+assert(rc.y == 7)
+assert(rc.width == 8)
+assert(rc.height == 9)
+
+-- Rectangle:contains
+
+local a = Rectangle{x=2, y=3, width=4, height=5}
+local b = Rectangle{x=3, y=4, width=1, height=1}
+assert(a:contains(b))
+assert(not b:contains(a))
+
+-- Rectangle:intersect
+
+assert(a:intersects(b))
+assert(b == a:intersect(b))
+
+a = Rectangle{x=2, y=3, width=4, height=5}
+b = Rectangle{x=3, y=4, width=4, height=5}
+c = Rectangle{x=3, y=4, width=3, height=4}
+assert(c == a:intersect(b))
+assert(c == b:intersect(a))
+assert((a & b) == c)
+
+-- Rectangle:union
+
+c = Rectangle{x=2, y=3, width=5, height=6}
+assert(c == a:union(b))
+assert(c == (a | b))
diff --git a/tests/scripts/save_file_command.lua b/tests/scripts/save_file_command.lua
new file mode 100644
index 000000000..b2963681c
--- /dev/null
+++ b/tests/scripts/save_file_command.lua
@@ -0,0 +1,142 @@
+-- Copyright (C) 2022  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+function fix_test_img(testImg, scale, fileExt, cm, c1)
+  -- With file formats that don't support alpha channel, we
+  -- compare totally transparent pixels (alpha=0) with black.
+  if fileExt == "tga" and cm == ColorMode.GRAYSCALE then
+    local pixel
+    if cm == ColorMode.RGB then
+      pixel = c1.rgbaPixel
+    elseif cm == ColorMode.GRAYSCALE then
+      pixel = c1.grayPixel
+    else
+      pixel = 0			-- Do nothing in indexed
+    end
+    for p in testImg:pixels() do
+      if p() == 0 then p(pixel) end
+    end
+  end
+  testImg:resize(testImg.width*scale, testImg.height*scale)
+end
+
+for _,cm in ipairs{ ColorMode.RGB,
+		    ColorMode.GRAYSCALE,
+		    ColorMode.INDEXED } do
+  local spr = Sprite(32, 32, cm)
+  spr.palettes[1]:resize(3)
+  spr.palettes[1]:setColor(0, Color(0, 0, 0, 0))
+  spr.palettes[1]:setColor(1, Color(0, 0, 0, 255))
+  spr.palettes[1]:setColor(2, Color(255, 0, 0, 255))
+
+  local c1, c2
+  if cm == ColorMode.RGB then
+    c1 = Color(0, 0, 0)
+    c2 = Color(255, 0, 0)
+  elseif cm == ColorMode.GRAYSCALE then
+    c1 = Color{ gray=0 }
+    c2 = Color{ gray=255 }
+  elseif cm == ColorMode.INDEXED then
+    c1 = 1
+    c2 = 2
+  end
+
+  app.useTool{ color=c1, brush=Brush(1),
+	       tool="filled_ellipse", points={{0,0},{31,31}} }
+  app.useTool{ color=c2, brush=Brush(1),
+	       tool="filled_ellipse", points={{4,4},{27,27}} }
+  spr.filename = "_test_a.aseprite"
+
+  app.command.SaveFile()
+  assert(spr.filename == "_test_a.aseprite")
+
+  app.command.SaveFileAs{ filename="_test_b.png" }
+  assert(spr.filename == "_test_b.png")
+
+  app.command.SaveFileCopyAs{ filename="_test_c.png" }
+  assert(spr.filename == "_test_b.png")
+
+  -- Scale
+  for _,fn in ipairs{ "_test_c_scaled.png",
+		      "_test_c_scaled.gif",
+		      "_test_c_scaled.fli",
+		      "_test_c_scaled.tga",
+		      "_test_c_scaled.bmp" } do
+    local fileExt = app.fs.fileExtension(fn)
+
+    -- TODO support saving any color mode to FLI files on the fly
+    if (fileExt ~= "fli" or cm == ColorMode.INDEXED) and
+       -- TODO Review grayscale support in bmp files
+       (fileExt ~= "bmp" or cm ~= ColorMode.GRAYSCALE) then
+      for _,scale in ipairs({ 1, 2, 3, 4 }) do
+	print(fn, scale, cm)
+
+	app.activeSprite = spr
+	app.command.SaveFileCopyAs{ filename=fn, scale=scale }
+	local c = app.open(fn)
+	assert(c.width == spr.width*scale)
+	assert(c.height == spr.height*scale)
+
+	-- GIF file is loaded as indexed, so we have to convert from
+	-- indexed to the ColorMode
+	if c.colorMode ~= cm then
+	  assert(fileExt == "gif" or fileExt == "bmp")
+
+	  if cm == ColorMode.RGB then
+	    app.activeSprite = c
+	    app.command.ChangePixelFormat{ format="rgb" }
+	  elseif cm == ColorMode.GRAYSCALE then
+	    app.activeSprite = c
+	    app.command.ChangePixelFormat{ format="grayscale" }
+	  else
+	    assert(false)
+	  end
+	end
+
+	local testImg = Image(spr.cels[1].image)
+	fix_test_img(testImg, scale, fileExt, cm, c1)
+	if not c.cels[1].image:isEqual(testImg) then
+	  c.cels[1].image:saveAs("_testA.png")
+	  testImg:saveAs("_testB.png")
+	end
+	assert(c.cels[1].image.colorMode == testImg.colorMode)
+	assert(c.cels[1].image:isEqual(testImg))
+      end
+    end
+  end
+
+  -- Scale + Slices
+  local slice = spr:newSlice(Rectangle(1, 2, 8, 15))
+  slice.name = "small_slice"
+  for _,fn in ipairs({ "_test_c_small_slice.png",
+		       -- TODO slices aren't supported in gif/fli yet
+		       --"_test_c_small_slice.gif",
+		       --"_test_c_small_slice.fli",
+		       "_test_c_small_slice.tga",
+		       "_test_c_small_slice.bmp" }) do
+    local fileExt = app.fs.fileExtension(fn)
+
+    if (fileExt ~= "bmp" or cm ~= ColorMode.GRAYSCALE) then
+      for _,scale in ipairs({ 1, 2, 3, 4 }) do
+	print(fn, scale, cm)
+
+	app.activeSprite = spr
+	app.command.SaveFileCopyAs{ filename=fn, slice="small_slice", scale=scale }
+	local c = app.open(fn)
+	assert(c.width == slice.bounds.width*scale)
+	assert(c.height == slice.bounds.height*scale)
+
+	local testImg = Image(spr.cels[1].image, spr.slices[1].bounds)
+	fix_test_img(testImg, scale, fileExt, cm, c1)
+	if not c.cels[1].image:isEqual(testImg) then
+	  c.cels[1].image:saveAs("_testA.png")
+	  testImg:saveAs("_testB.png")
+	end
+	assert(c.cels[1].image:isEqual(testImg))
+      end
+    end
+  end
+
+end
diff --git a/tests/scripts/selection.lua b/tests/scripts/selection.lua
new file mode 100644
index 000000000..2b0cd8249
--- /dev/null
+++ b/tests/scripts/selection.lua
@@ -0,0 +1,121 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+-- Isolated selection
+do
+  local a = Selection()
+  assert(a.bounds.x == 0)
+  assert(a.bounds.y == 0)
+  assert(a.bounds.width == 0)
+  assert(a.bounds.height == 0)
+  assert(a.isEmpty)
+
+  a:select(1, 2, 3, 4)
+  assert(a.bounds.x == 1)
+  assert(a.bounds.y == 2)
+  assert(a.bounds.width == 3)
+  assert(a.bounds.height == 4)
+  assert(not a.isEmpty)
+  assert(a:contains(1, 2))
+  assert(a:contains(1+3-1, 2+4-1))
+  assert(not a:contains(0, 1))
+  assert(not a:contains(1+3, 2+4))
+
+  a:select{x=5, y=6, width=7, height=8}
+  assert(a.bounds.x == 5)
+  assert(a.bounds.y == 6)
+  assert(a.bounds.width == 7)
+  assert(a.bounds.height == 8)
+
+  a:deselect()
+  assert(a.bounds.x == 0)
+  assert(a.bounds.y == 0)
+  assert(a.bounds.width == 0)
+  assert(a.bounds.height == 0)
+  assert(a.isEmpty)
+  assert(not a:contains(0, 0))
+
+  -- Constructor with rectangles
+  local b = Selection(1, 2, 3, 4)
+  assert(b.bounds == Rectangle(1, 2, 3, 4))
+  assert(b.origin == Point(1, 2))
+
+  -- Move
+  b.origin = Point(5, 6)
+  assert(b.bounds == Rectangle(5, 6, 3, 4))
+  assert(b.origin == Point(5, 6))
+end
+
+-- Sprite Selection
+do
+  local spr = Sprite(32, 32)
+  local sel = spr.selection
+  assert(sel.bounds.x == 0)
+  assert(sel.bounds.y == 0)
+  assert(sel.bounds.width == 0)
+  assert(sel.bounds.height == 0)
+
+  sel:selectAll()
+  assert(sel.bounds.x == 0)
+  assert(sel.bounds.y == 0)
+  assert(sel.bounds.width == spr.width)
+  assert(sel.bounds.height == spr.height)
+
+  sel:select(2, 3, 4, 5)
+  assert(sel.bounds.x == 2)
+  assert(sel.bounds.y == 3)
+  assert(sel.bounds.width == 4)
+  assert(sel.bounds.height == 5)
+
+  sel.origin = Point(5, 6)
+  assert(sel.bounds == Rectangle(5, 6, 4, 5))
+end
+
+-- Comparison
+do
+  local a = Selection()
+  local b = Selection()
+  assert(a == b)
+
+  a:select(0, 0, 1, 1)
+  assert(a ~= b)
+
+  b:add(a)
+  assert(a == b)
+
+  a:subtract(b)
+  assert(a ~= b)
+
+  b:subtract(b)
+  assert(a == b)
+end
+
+-- Operations
+do
+  local a = Selection()
+  a:select(2, 3, 4, 5)
+  assert(a.bounds == Rectangle(2, 3, 4, 5))
+
+  a:subtract(2, 3, 4, 1)
+  assert(a.bounds == Rectangle(2, 4, 4, 4))
+
+  assert(a:contains(3, 5))
+  a:subtract(3, 5, 1, 1)
+  assert(not a:contains(3, 5))
+  assert(a.bounds == Rectangle(2, 4, 4, 4))
+
+  local b = Selection()
+  assert(a.bounds == Rectangle(2, 4, 4, 4))
+  assert(b.isEmpty)
+  a:subtract(b) -- This should be a no-op because b is empty
+  assert(a.bounds == Rectangle(2, 4, 4, 4))
+
+  b:select(0, 0, 32, 32)
+  assert(a ~= b)
+  b:intersect(a)
+  assert(a == b)
+  assert(b.bounds == Rectangle(2, 4, 4, 4))
+  assert(b.bounds == Rectangle(2, 4, 4, 4))
+end
diff --git a/tests/scripts/selection_tools.lua b/tests/scripts/selection_tools.lua
new file mode 100644
index 000000000..24fa8791b
--- /dev/null
+++ b/tests/scripts/selection_tools.lua
@@ -0,0 +1,28 @@
+-- Copyright (C) 2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+----------------------------------------------------------------------
+-- Test magic wand in transparent layer
+-- Note: A regression in the beta was found in this case.
+
+do
+  local s = Sprite(4, 4, ColorMode.INDEXED)
+  app.command.LayerFromBackground()
+
+  local i = s.cels[1].image
+  i:clear(0)
+  i:putPixel(0, 0, 1)
+  expect_eq(4, i.width)
+  expect_eq(4, i.height)
+
+  app.useTool{ tool='magic_wand', points={Point(0, 0)} }
+  expect_eq(Rectangle(0, 0, 1, 1), s.selection.bounds)
+
+  app.useTool{ tool='magic_wand', points={Point(1, 0)} }
+  expect_eq(Rectangle(0, 0, 4, 4), s.selection.bounds)
+  assert(not s.selection:contains(0, 0))
+end
diff --git a/tests/scripts/size.lua b/tests/scripts/size.lua
new file mode 100644
index 000000000..1cd6d661a
--- /dev/null
+++ b/tests/scripts/size.lua
@@ -0,0 +1,75 @@
+-- Copyright (C) 2019  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+local sz = Size()
+assert(sz.width == 0)
+assert(sz.height == 0)
+
+sz = Size(3, 4)
+assert(sz.width == 3)
+assert(sz.height == 4)
+assert("Size{ width=3, height=4 }" == tostring(sz))
+
+local sz2 = Size(sz)
+assert(sz2.width == 3)
+assert(sz2.height == 4)
+
+sz.width = 7
+sz.height = 8
+assert(sz.width == 7)
+assert(sz.height == 8)
+
+sz = Size{width=10, height=20}
+assert(sz.width == 10)
+assert(sz.height == 20)
+
+sz = Size{45, 25}
+assert(sz.width == 45)
+assert(sz.height == 25)
+
+sz = -sz
+assert(sz.width == -45)
+assert(sz.height == -25)
+
+-- add/sub/mul/div/mod/pow/idiv
+
+sz = Size(1, 2) + 4
+sz2 = 4 + Size(1, 2)
+assert(sz.width == 5)
+assert(sz.height == 6)
+assert(sz == sz2)
+
+sz = Size(1, 2) + Size(3, 4)
+assert(sz.width == 4)
+assert(sz.height == 6)
+
+sz = Size(3, 4) - 1
+assert(sz.width == 2)
+assert(sz.height == 3)
+
+sz = Size(8, 5) - Size(3, 2)
+assert(sz.width == 5)
+assert(sz.height == 3)
+
+sz = Size(6, 10) * 2
+assert(sz.width == 12)
+assert(sz.height == 20)
+
+sz = Size(6, 10) / 2
+assert(sz.width == 3)
+assert(sz.height == 5)
+
+sz = Size(10, 5) % 2
+assert(sz.width == 0)
+assert(sz.height == 1)
+
+sz = Size(2, 5) ^ 2
+assert(sz.width == 4)
+assert(sz.height == 25)
+
+sz = Size(31, 10) // 3
+assert(sz.width == 10)
+assert(sz.height == 3)
diff --git a/tests/scripts/slice.lua b/tests/scripts/slice.lua
new file mode 100644
index 000000000..3794e4a3e
--- /dev/null
+++ b/tests/scripts/slice.lua
@@ -0,0 +1,27 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local s = Sprite(32, 32)
+
+  local a = s:newSlice(0, 0, 32, 32)
+  assert(a.bounds == Rectangle(0, 0, 32, 32))
+  assert(a.sprite == s)
+
+  assert(a.name == "Slice")
+  a.name = "Slice A"
+  assert(a.name == "Slice A")
+
+  assert(a.center == nil)
+  a.center = Rectangle(2, 3, 28, 20)
+  assert(a.center == Rectangle(2, 3, 28, 20))
+
+  assert(a.pivot == nil)
+  a.pivot = Point(16, 17)
+  assert(a.pivot == Point(16, 17))
+
+  a.data = "Data"
+  assert(a.data == "Data")
+end
diff --git a/tests/scripts/slices.lua b/tests/scripts/slices.lua
new file mode 100644
index 000000000..42e3d2589
--- /dev/null
+++ b/tests/scripts/slices.lua
@@ -0,0 +1,40 @@
+-- Copyright (C) 2022  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local s = Sprite(32, 32)
+
+  local a = s:newSlice()
+  local b = s:newSlice(0, 2, 8, 10)
+  local c = s:newSlice{ x=0, y=0, width=32, height=32 }
+  assert(a.bounds == nil)
+  assert(b.bounds == Rectangle(0, 2, 8, 10))
+  assert(c.bounds == Rectangle(0, 0, 32, 32))
+
+  local bounds = { nil, Rectangle(0, 2, 8, 10), Rectangle(0, 0, 32, 32) }
+
+  local i = 1
+  for k,v in ipairs(s.slices) do
+    assert(i == k)
+    assert(v == s.slices[k])
+    assert(bounds[i] == s.slices[k].bounds)
+    i = i+1
+  end
+
+  s:deleteSlice(b)
+  assert(a == s.slices[1])
+  assert(c == s.slices[2])
+
+  assert(2 == #s.slices)
+  app.undo()
+  assert(3 == #s.slices)
+  app.undo()
+  assert(2 == #s.slices)
+  app.undo()
+  assert(1 == #s.slices)
+  app.undo()
+  assert(0 == #s.slices)
+end
diff --git a/tests/scripts/sprite.lua b/tests/scripts/sprite.lua
new file mode 100644
index 000000000..16f52be5d
--- /dev/null
+++ b/tests/scripts/sprite.lua
@@ -0,0 +1,208 @@
+-- Copyright (C) 2019-2022  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local a = Sprite(32, 64)
+  assert(a.width == 32)
+  assert(a.height == 64)
+  assert(a.colorMode == ColorMode.RGB) -- RGB by default
+  assert(a.bounds == Rectangle{x=0, y=0, width=32, height=64})
+
+  -- Crop and resize
+  a.selection:select(2, 3, 4, 5)
+  a:crop()
+  assert(a.width == 4)
+  assert(a.height == 5)
+  assert(a.cels[1].image.width == 32)
+  assert(a.cels[1].image.height == 64)
+  a:resize(6, 8)
+  assert(a.width == 6)
+  assert(a.height == 8)
+  assert(a.cels[1].image.width == 32 * 6 / 4) -- Check that the image was resized (not only the canvas)
+  assert(a.cels[1].image.height == 64 * 8 / 5)
+  a:crop{x=-1, y=-1, width=20, height=30}
+  assert(a.width == 20)
+  assert(a.height == 30)
+
+  -- Resize sprite setting width/height (just changing canvas size)
+  a.width = 8
+  a.height = 10
+  assert(a.width == 8)
+  assert(a.height == 10)
+
+  -- Test other Sprite() constructors
+  local b = Sprite(4, 8, ColorMode.INDEXED)
+  assert(b.width == 4)
+  assert(b.height == 8)
+  assert(b.colorMode == ColorMode.INDEXED)
+
+  local c = Sprite{ colorMode=ColorMode.INDEXED, width=10, height=20 }
+  assert(c.width == 10)
+  assert(c.height == 20)
+  assert(c.colorMode == ColorMode.INDEXED)
+
+  local d = Sprite{ fromFile="sprites/abcd.aseprite" }
+  assert(#d.layers == 4)
+  assert(d.width == 32)
+  assert(d.height == 32)
+  assert(d.colorMode == ColorMode.INDEXED)
+end
+
+-- Transparent color
+
+do
+  local a = Sprite(32, 32, ColorMode.INDEXED)
+  assert(a.transparentColor == 0)
+  a.transparentColor = 8
+  assert(a.transparentColor == 8)
+end
+
+-- Palette
+
+do
+  local a = Sprite(32, 32, ColorMode.INDEXED)
+  assert(#a.palettes == 1)
+  assert(#a.palettes[1] == 256)
+
+  local p = Palette(3)
+  p:setColor(0, Color(255, 0, 0))
+  p:setColor(1, Color(0, 255, 0))
+  p:setColor(2, Color(0, 0, 255))
+  a:setPalette(p)
+
+  assert(#a.palettes == 1)
+  assert(#a.palettes[1] == 3)
+  assert(a.palettes[1]:getColor(0) == Color(255, 0, 0))
+  assert(a.palettes[1]:getColor(1) == Color(0, 255, 0))
+  assert(a.palettes[1]:getColor(2) == Color(0, 0, 255))
+end
+
+-- Duplicate & Flatten
+
+do
+  local a = Sprite(32, 32)
+  a:newLayer()
+  a:newLayer()
+  assert(#a.layers == 3)
+
+  local b = Sprite(a)           -- Clone a
+  a:flatten()                   -- Flatten a
+  assert(#a.layers == 1)
+  assert(#b.layers == 3)
+end
+
+-- Resize non-active sprite
+do
+  local a = Sprite(32, 32)
+  local b = Sprite(64, 64)
+  app.activeSprite = a
+  a:resize(10, 10)
+  b:resize(20, 20)
+  assert(a.width == 10)
+  assert(a.height == 10)
+  assert(b.width == 20)
+  assert(b.height == 20)
+  app.undo()
+  assert(a.width == 32)
+  assert(a.height == 32)
+  app.activeSprite = b
+  app.undo()
+  assert(b.width == 64)
+  assert(b.height == 64)
+end
+
+-- Grid bounds
+do
+  local s = Sprite(32, 32)
+  assert(s.gridBounds == Rectangle{0, 0, 16, 16})
+  s.gridBounds = Rectangle{2, 3, 8, 4}
+  assert(s.gridBounds == Rectangle{2, 3, 8, 4})
+  s:saveAs("_test_sprite_gridbounds.aseprite")
+
+  local s2 = Sprite{ fromFile="_test_sprite_gridbounds.aseprite" }
+  assert(s2.gridBounds == Rectangle{2, 3, 8, 4})
+end
+
+-- Pixel ratio
+do
+  local s = Sprite(32, 32)
+  assert(s.pixelRatio == Size{1, 1})
+  s.pixelRatio = Size{3, 2}
+  assert(s.pixelRatio == Size{3, 2})
+  s:saveAs("_test_sprite_pixelratio.aseprite")
+
+  local s2 = Sprite{ fromFile="_test_sprite_pixelratio.aseprite" }
+  assert(s2.pixelRatio == Size{3, 2})
+end
+
+-- Sprite{ fromFile, oneFrame }
+do
+  local s = Sprite(32, 32)
+  s:newFrame()
+  s:saveAs("_test1.png")
+  assert(#s.frames == 2)
+
+  s = Sprite{ fromFile="_test1.png" }
+  assert(#s.frames == 2)
+
+  s = Sprite{ fromFile="_test1.png", oneFrame=true }
+  assert(#s.frames == 1)
+
+  s = Sprite{ fromFile="_test1.png", oneFrame=false }
+  assert(#s.frames == 2)
+end
+
+-- Issues with sprites having pixel with indexes out of palette bounds:
+-- Saving png failed (https://github.com/aseprite/aseprite/issues/2842)
+do
+  local s = Sprite(2, 2, ColorMode.INDEXED)
+  assert(#s.palettes == 1)
+
+  s.transparentColor = 1
+  s.palettes[1]:resize(8)
+  assert(#s.palettes[1] == 8)
+  s.cels[1].image:clear(2)
+  s.cels[1].image:putPixel(0, 0, 7)
+  s:saveAs("_test1_.png")  -- OK
+
+  s.palettes[1]:resize(4)
+  assert(#s.palettes[1] == 4)
+  local result = s:saveAs("_test2_palerr_.png") -- Used to fail
+
+  -- If result=false we got a "libpng: Wrote palette index exceeding num_palette"
+  assert(result)
+
+  local s2 = app.open("_test2_palerr_.png")
+  assert(s2 ~= nil)
+  print(s2.cels[1].image:getPixel(0, 0))
+  assert(s2.cels[1].image:getPixel(0, 0) == 1)
+end
+-- Flatten visible layers uses indices outside the palette range as opaque colors instead of transparent color (https://github.com/aseprite/aseprite/issues/2912)
+do
+  local s = Sprite(2, 2, ColorMode.INDEXED)
+
+  s.transparentColor = 0
+  s.palettes[1]:resize(4)
+
+  s.cels[1].image:clear(1)
+  local l = s:newLayer()
+  s:newCel(l)
+  s.cels[2].image:putPixel(0, 0, 2)
+  s.cels[2].image:putPixel(1, 0, 7)
+  s:flatten()
+
+  assert(s.cels[1].image:getPixel(0, 0) == 2)
+  assert(s.cels[1].image:getPixel(1, 0) == 1) -- Get the color of the first layer
+end
+
+-- Compare sprite IDs
+
+do
+  local a = Sprite(1, 1)
+  local b = Sprite(1, 1)
+  assert(a == a)
+  assert(a ~= b) -- Compares IDs, not sprite size
+end
diff --git a/tests/scripts/string.lua b/tests/scripts/string.lua
new file mode 100644
index 000000000..117fd5beb
--- /dev/null
+++ b/tests/scripts/string.lua
@@ -0,0 +1,23 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+assert(72 == string.byte("Hello", 1))
+assert(101 == string.byte("Hello", 2))
+assert(111 == string.byte("Hello", 5))
+assert("Hello" == string.char(72, 101, 108, 108, 111))
+
+local s = "Hello"
+assert(111 == s:byte(5))
+assert(5 == string.len(s))
+assert("olleH" == string.reverse(s))
+assert("hello" == string.lower(s))
+assert("HELLO" == string.upper(s))
+
+assert("Simple int 32" == string.format("Simple int %d", 32))
+assert("Simple int 0032" == string.format("Simple int %04d", 32))
+
+assert(7 == string.find("Hello World!", "W"))
+
+assert("-- hi 1000 --" == string.format("-- %s %d --", "hi", 1000))
diff --git a/tests/scripts/tag.lua b/tests/scripts/tag.lua
new file mode 100644
index 000000000..2d38fd881
--- /dev/null
+++ b/tests/scripts/tag.lua
@@ -0,0 +1,45 @@
+-- Copyright (C) 2020  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local s = Sprite(32, 32)
+  for i = 1,7 do s:newFrame() end
+  assert(#s.frames == 8)
+
+  a = s:newTag(1, 8)
+  assert(a.sprite == s)
+  assert(a.fromFrame.frameNumber == 1)
+  assert(a.toFrame.frameNumber == 8)
+  assert(a.frames == 8)
+
+  a.fromFrame = 2
+  a.toFrame = 5
+  assert(a.fromFrame.frameNumber == 2)
+  assert(a.toFrame.frameNumber == 5)
+
+  assert(a.name == "Tag")
+  a.name = "Tag A"
+  assert(a.name == "Tag A")
+
+  assert(a.aniDir == AniDir.FORWARD) -- Default AniDir is FORWARD
+  a.aniDir = AniDir.REVERSE
+  assert(a.aniDir == AniDir.REVERSE)
+  a.aniDir = AniDir.PING_PONG
+  assert(a.aniDir == AniDir.PING_PONG)
+  a.aniDir = AniDir.FORWARD
+  assert(a.aniDir == AniDir.FORWARD)
+
+  assert(a.color == Color(0, 0, 0))
+  a.color = Color(255, 0, 0)
+  assert(a.color == Color(255, 0, 0))
+
+  assert(a.repeats == 0)
+  a.repeats = 1
+  assert(a.repeats == 1)
+
+  a.data = "Data"
+  assert(a.data == "Data")
+end
diff --git a/tests/scripts/tags.lua b/tests/scripts/tags.lua
new file mode 100644
index 000000000..edfef359c
--- /dev/null
+++ b/tests/scripts/tags.lua
@@ -0,0 +1,36 @@
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+do
+  local s = Sprite(32, 32)
+  for i = 1,7 do s:newFrame() end
+  assert(#s.frames == 8)
+
+  a = s:newTag(1, 2)
+  b = s:newTag(3, 4)
+  c = s:newTag(5, 8)
+
+  assert(a.frames == 2)
+  assert(b.frames == 2)
+  assert(c.frames == 4)
+
+  assert(a == s.tags[1])
+  assert(b == s.tags[2])
+  assert(c == s.tags[3])
+
+  local i = 1
+  for k,v in ipairs(s.tags) do
+    assert(i == k)
+    assert(v == s.tags[k])
+    i = i+1
+  end
+
+  s:deleteTag(b)
+  assert(a == s.tags[1])
+  assert(c == s.tags[2])
+
+  assert(c.fromFrame.frameNumber == 5)
+  assert(c.toFrame.frameNumber == 8)
+end
diff --git a/tests/scripts/test_utils.lua b/tests/scripts/test_utils.lua
new file mode 100644
index 000000000..28e208fad
--- /dev/null
+++ b/tests/scripts/test_utils.lua
@@ -0,0 +1,134 @@
+-- Copyright (C) 2019-2020  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+function expect_eq(a, b)
+  if a ~= b then
+    print(debug.traceback())
+    print('Expected A == B but:')
+    print(' - Value A = ' .. tostring(a))
+    print(' - Value B = ' .. tostring(b))
+    assert(a == b)
+  end
+end
+
+local function dump_img(image)
+  local w = image.width
+  local h = image.height
+  print('Image(' .. tostring(w) .. 'x' .. tostring(h) .. ') = {')
+  for v=0,h-1 do
+    local lineStr = '  '
+    for u=0,w-1 do
+      lineStr = lineStr .. image:getPixel(u, v) .. ','
+    end
+    print(lineStr)
+  end
+  print('}')
+end
+
+function expect_img(image, expectedPixels)
+  local w = image.width
+  local h = image.height
+  if w*h ~= #expectedPixels then
+    print(debug.traceback())
+    print('Expected pixels: #=' .. #expectedPixels) 
+    print('Image size: w=' .. w .. ' h=' .. h .. ' #=' .. w*h)
+    dump_img(image)
+    assert(w*h == #expectedPixels)
+  end
+  for y=0,h-1 do
+    for x=0,w-1 do
+      local value = image:getPixel(x, y)
+      local expected = expectedPixels[1+y*w+x]
+      if value ~= expected then
+	dump_img(image)
+        print('In pixel (' .. x .. ', ' .. y .. '):')
+
+	local a = value
+	local b = expected
+	print(debug.traceback())
+	print('Expected A == B but:')
+	if image.colorMode == ColorMode.RGB then
+	  print(string.format(' - Value A = rgba(%d,%d,%d,%d)',
+			      app.pixelColor.rgbaR(a),
+			      app.pixelColor.rgbaG(a),
+			      app.pixelColor.rgbaB(a),
+			      app.pixelColor.rgbaA(a)))
+	  print(string.format(' - Value B = rgba(%d,%d,%d,%d)',
+			      app.pixelColor.rgbaR(b),
+			      app.pixelColor.rgbaG(b),
+			      app.pixelColor.rgbaB(b),
+			      app.pixelColor.rgbaA(b)))
+	elseif image.colorMode == ColorMode.GRAY then
+	  print(string.format(' - Value A = gray(%d,%d)',
+			      app.pixelColor.grayaV(a),
+			      app.pixelColor.grayaA(a)))
+	  print(string.format(' - Value B = gray(%d,%d)',
+			      app.pixelColor.grayaV(b),
+			      app.pixelColor.grayaA(b)))
+	else
+	  print(' - Value A = ' .. tostring(a))
+	  print(' - Value B = ' .. tostring(b))
+	end
+	assert(a == b)
+      end
+    end
+  end
+end
+
+function expect_img_msg(image, expectedPixels, msg)
+  local status, err = pcall(expect_img, image, expectedPixels)
+  if not status then
+    print(msg)
+    error(err)
+  end
+end
+
+function array_to_pixels(array, image)
+  local w = image.width
+  local h = image.height
+  assert(w*h == #array)
+  local i = 1
+  for y=0,h-1 do
+    for x=0,w-1 do
+      image:drawPixel(x, y, array[i])
+      i = i+1
+    end
+  end
+end
+
+-- Returns true if the given array (layers) of layers
+function expect_rendered_layers(expectedImage, sprite, layerNames, frame)
+  function contains_layer(name)
+    for _,n in ipairs(layerNames) do
+      if name == n then return true end
+    end
+    return false
+  end
+
+  if frame == nil then frame = 1 end
+  local render = Image(sprite.spec)
+  function render_layers(prefix, layers)
+    for _,layer in ipairs(layers) do
+      if layer.isGroup then
+	render_layers(layer.name.."/", layer.layers)
+      end
+      if contains_layer(prefix..layer.name) then
+	local cel = layer:cel(frame)
+	if cel then
+	  render:drawImage(cel.image, cel.position)
+	end
+      end
+    end
+  end
+
+  render_layers("", sprite.layers)
+  if not expectedImage:isEqual(render) then
+    print("Rendering:")
+    for _,n in ipairs(layerNames) do
+      print("  - " .. n)
+    end
+    error("render doesn't match to the expected image")
+  end
+end
diff --git a/tests/scripts/tilemap.lua b/tests/scripts/tilemap.lua
new file mode 100644
index 000000000..2eb38560d
--- /dev/null
+++ b/tests/scripts/tilemap.lua
@@ -0,0 +1,1119 @@
+-- Copyright (C) 2019-2021  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+-- This version of Aseprite doesn't support tilemaps
+if TilesetMode == nil then return end
+
+dofile('./test_utils.lua')
+
+local rgba = app.pixelColor.rgba
+
+-- Check constants
+assert(TilemapMode.PIXELS == 0)
+assert(TilemapMode.TILES == 1)
+assert(TilesetMode.MANUAL == 0)
+assert(TilesetMode.AUTO == 1)
+assert(TilesetMode.STACK == 2)
+
+----------------------------------------------------------------------
+-- Tests drawing in the tilemap
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 32, ColorMode.INDEXED)
+  spr.gridBounds = Rectangle{ 0, 0, 4, 4 }
+  assert(spr.layers[1].isImage)
+  assert(not spr.layers[1].isTilemap)
+
+  ----------------------------------------------------------------------
+  -- Create a tilemap
+  ----------------------------------------------------------------------
+
+  app.command.NewLayer{ tilemap=true }
+  assert(#spr.layers == 2)
+  local tilemapLay = spr.layers[2]
+  assert(tilemapLay.isImage)
+  assert(tilemapLay.isTilemap)
+  assert(#tilemapLay.cels == 0)
+
+  ----------------------------------------------------------------------
+  -- Draw the first pixel on the tilemap so a new tile is created
+  ----------------------------------------------------------------------
+
+  app.useTool{
+    tool='pencil',
+    color=1,
+    layer=tilemapLay,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(1, 2), Point(2, 2) }}
+  assert(#tilemapLay.cels == 1)
+  assert(tilemapLay:cel(1).image.colorMode == ColorMode.TILEMAP)
+  local tilemapCel = tilemapLay:cel(1)
+  assert(tilemapCel.bounds == Rectangle(0, 0, 4, 4))
+
+  assert(#spr.tilesets == 1) -- one tileset
+  assert(spr.tilesets[1] == tilemapLay.tileset)
+
+  local tileset = tilemapLay.tileset
+  assert(#tileset == 2) -- empty tile + our tile
+  assert(tileset:getTile(0):isEmpty())
+  assert(not tileset:getTile(1):isEmpty())
+  expect_img(tileset:getTile(1), { 0,0,0,0,
+                                   0,0,0,0,
+                                   0,1,1,0,
+                                   0,0,0,0 })
+
+  tilemapCel.position = Point(2, 2)
+  assert(tilemapCel.bounds == Rectangle(2, 2, 4, 4))
+  assert(#tileset == 2)
+
+  assert(tilemapCel.image.width == 1)
+  assert(tilemapCel.image.height == 1)
+  assert(tilemapCel.image:getPixel(0, 0) == 1)
+
+  ----------------------------------------------------------------------
+  -- Draw a second pixel with locked mode (new tiles are not generated)
+  ----------------------------------------------------------------------
+
+  app.useTool{
+    tool='pencil',
+    color=1,
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.MANUAL,
+    points={ Point(0, 0) }}
+
+  assert(tilemapCel.bounds == Rectangle(2, 2, 4, 4))
+  assert(#tileset == 2)
+
+  ----------------------------------------------------------------------
+  -- Draw pixels generating new tiles
+  ----------------------------------------------------------------------
+
+  app.useTool{
+    tool='pencil',
+    color=1,
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0) }}
+
+  assert(tilemapCel.bounds == Rectangle(-2, -2, 8, 8))
+  assert(#tileset == 3)
+  assert(tileset:getTile(0):isEmpty())
+  assert(not tileset:getTile(1):isEmpty())
+  assert(not tileset:getTile(2):isEmpty())
+  expect_img(tilemapCel.image, { 2, 0,
+                                 0, 1 })
+
+  app.useTool{
+    tool='pencil',
+    color=1,
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(6, 6) }}
+
+  assert(tilemapCel.bounds == Rectangle(-2, -2, 12, 12))
+  assert(#tileset == 4)
+  assert(not tileset:getTile(3):isEmpty())
+  expect_img(tilemapCel.image, { 2, 0, 0,
+                                 0, 1, 0,
+                                 0, 0, 3 })
+
+  ----------------------------------------------------------------------
+  -- Draw in manual mode to modify existent tiles
+  ----------------------------------------------------------------------
+
+  assert(tilemapCel.bounds == Rectangle(-2, -2, 12, 12))
+  assert(#tileset == 4)
+  expect_img(tileset:getTile(1), { 0,0,0,0,
+                                   0,0,0,0,
+                                   0,1,1,0,
+                                   0,0,0,0 })
+  expect_img(tileset:getTile(2), { 0,0,0,0,
+                                   0,0,0,0,
+                                   0,0,1,0,
+                                   0,0,0,0 })
+  expect_img(tileset:getTile(3), { 1,0,0,0,
+                                   0,0,0,0,
+                                   0,0,0,0,
+                                   0,0,0,0 })
+  expect_img(tilemapCel.image, { 2, 0, 0,
+                                 0, 1, 0,
+                                 0, 0, 3 })
+
+  app.useTool{
+    tool='rectangle',
+    color=2,
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.MANUAL,
+    points={ Point(0, 0), Point(9, 9) }}
+
+  assert(tilemapCel.bounds == Rectangle(-2, -2, 12, 12))
+  assert(#tileset == 4)
+  expect_img(tileset:getTile(1), { 0,0,0,0,
+                                   0,0,0,0,
+                                   0,1,1,0,
+                                   0,0,0,0 })
+  expect_img(tileset:getTile(2), { 0,0,0,0,
+                                   0,0,0,0,
+                                   0,0,2,2,
+                                   0,0,2,0 })
+  expect_img(tileset:getTile(3), { 1,0,0,2,
+                                   0,0,0,2,
+                                   0,0,0,2,
+                                   2,2,2,2 })
+  expect_img(tilemapCel.image, { 2, 0, 0,
+                                 0, 1, 0,
+                                 0, 0, 3 })
+
+  tilemapCel.position = Point(1, 1)
+  app.useTool{
+    tool='line',
+    color=3,
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.MANUAL,
+    points={ Point(1, 1), Point(12, 12) }}
+
+  assert(tilemapCel.bounds == Rectangle(1, 1, 12, 12))
+  assert(#tileset == 4)
+  expect_img(tileset:getTile(1), { 3,0,0,0,
+                                   0,3,0,0,
+                                   0,1,3,0,
+                                   0,0,0,3 })
+  expect_img(tileset:getTile(2), { 3,0,0,0,
+                                   0,3,0,0,
+                                   0,0,3,2,
+                                   0,0,2,3 })
+  expect_img(tileset:getTile(3), { 3,0,0,2,
+                                   0,3,0,2,
+                                   0,0,3,2,
+                                   2,2,2,3 })
+  expect_img(tilemapCel.image, { 2, 0, 0,
+                                 0, 1, 0,
+                                 0, 0, 3 })
+
+end
+
+----------------------------------------------------------------------
+-- Tests drawing in the tilemap with tiles
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 32)
+  spr.gridBounds = Rectangle(0, 0, 8, 8)
+  app.command.NewLayer{ tilemap=true }
+
+  local tm = app.activeLayer
+  local ts = tm.tileset
+  assert(ts ~= nil)
+  expect_eq(0, ts.grid.origin.x)
+  expect_eq(0, ts.grid.origin.y)
+  expect_eq(8, ts.grid.tileSize.width)
+  expect_eq(8, ts.grid.tileSize.height)
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=0, b=0 },
+    tilemapMode=TilesetMode.PIXELS,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0), Point(31, 31) }}
+
+  local cel = tm.cels[1]
+  expect_eq(2, #ts)
+  expect_img(cel.image, { 1,0,0,0,
+                          0,1,0,0,
+                          0,0,1,0,
+                          0,0,0,1 })
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ index=1 },
+    tilemapMode=TilemapMode.TILES,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 16) }} -- y=16 is the first pixel of 3rd row of tiles
+  cel = tm.cels[1]
+  expect_img(cel.image, { 1,0,0,0,
+                          0,1,0,0,
+                          1,0,1,0,
+                          0,0,0,1 })
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ index=1 },
+    tilemapMode=TilemapMode.TILES,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0), Point(16, 0) }} -- x=16 is the first pixel of 3rd column of tiles
+  cel = tm.cels[1]
+  expect_img(cel.image, { 1,1,1,0,
+                          0,1,0,0,
+                          1,0,1,0,
+                          0,0,0,1 })
+
+  -- Move layer origin to 10, 8
+  cel.position = { 10, 8 }
+  expect_eq(Point{ 10, 8 }, cel.position)
+  app.useTool{
+    tool='pencil',
+    color=Color{ index=0 },
+    tilemapMode=TilemapMode.TILES,
+    tilesetMode=TilesetMode.STACK,
+    points={ { 10, 8 }, { 18, 16 } }} -- {10,8} is the first existent tile in the tilemap
+                                      -- these are tiles 2,1 and 3,2
+  cel = tm.cels[1]
+  expect_img(cel.image, { 0,1,1,0,
+                          0,0,0,0,
+                          1,0,1,0,
+                          0,0,0,1 })
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ index=1 },
+    tilemapMode=TilemapMode.TILES,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(1, 7), Point(2, 8) }} -- Tile 0,0 and 1,1
+
+  cel = tm.cels[1]
+  expect_img(cel.image, { 1,0, 0,0,0,0,
+                          0,1, 0,1,1,0,
+                          0,0, 0,0,0,0,
+                          0,0, 1,0,1,0,
+                          0,0, 0,0,0,1 })
+
+end
+
+----------------------------------------------------------------------
+-- Tests drawing when the grid origin is in a negative position
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 32)
+  app.command.NewLayer{ tilemap=true }
+  local tilemapLay = spr.layers[2]
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=255, b=0 },
+    layer=tilemapLay,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0) }}
+  local tilemapCel = tilemapLay:cel(1)
+  assert(tilemapCel.bounds == Rectangle(0, 0, 16, 16))
+
+  local tileset = tilemapLay.tileset
+  assert(#tileset == 2) -- empty tile + our tile
+
+  tilemapCel.position = Point(-1, -1)
+  assert(tilemapCel.bounds == Rectangle(-1, -1, 16, 16))
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0) }}
+
+  assert(tilemapCel.bounds == Rectangle(-1, -1, 16, 16))
+  assert(#tileset == 3)
+
+  local img = tileset:getTile(2)
+
+  assert(img:getPixel(0, 0) == rgba(0, 255, 0, 255))
+  assert(img:getPixel(1, 0) == rgba(0, 0, 0, 0))
+  assert(img:getPixel(2, 0) == rgba(0, 0, 0, 0))
+
+  assert(img:getPixel(0, 1) == rgba(0, 0, 0, 0))
+  assert(img:getPixel(1, 1) == rgba(255, 0, 0, 255))
+  assert(img:getPixel(2, 1) == rgba(0, 0, 0, 0))
+
+  assert(img:getPixel(0, 2) == rgba(0, 0, 0, 0))
+  assert(img:getPixel(1, 2) == rgba(0, 0, 0, 0))
+  assert(img:getPixel(2, 2) == rgba(0, 0, 0, 0))
+end
+
+----------------------------------------------------------------------
+-- Tests that extra tiles are not created
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 32)
+  app.command.NewLayer{ tilemap=true }
+  local tilemapLay = spr.layers[2]
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=255, b=0 },
+    layer=tilemapLay,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0) }}
+  local tilemapCel = tilemapLay:cel(1)
+  tilemapCel.position = Point(-1, -1)
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    cel=tilemapCel,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(30, 30) }}
+
+  assert(tilemapCel.bounds == Rectangle(-1, -1, 32, 32))
+end
+
+----------------------------------------------------------------------
+-- Tests moving & copying tiles
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 32)
+  app.command.NewLayer{ tilemap=true }
+  local tilemapLay = spr.layers[2]
+
+  app.useTool{
+    tool='ellipse',
+    color=Color{ r=0, g=0, b=0 },
+    layer=tilemapLay,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0), Point(31, 31) }}
+
+  local ts = tilemapLay.tileset
+  assert(#ts == 5)
+
+  local imgs = { ts:getTile(1),
+                 ts:getTile(2),
+                 ts:getTile(3),
+                 ts:getTile(4) }
+
+  -- No op = move tile 1 before the tile 1, result=0,1,2,3,4
+  app.range.tiles = { 1 }
+  app.command.MoveTiles{ before=1 }
+  expect_eq(imgs[1], ts:getTile(1))
+  expect_eq(imgs[2], ts:getTile(2))
+  expect_eq(imgs[3], ts:getTile(3))
+  expect_eq(imgs[4], ts:getTile(4))
+  expect_eq(1, #app.range.tiles)
+  expect_eq(1, app.range.tiles[1])
+
+  -- Move tile 2 before tile 1, result=0,2,1,3,4
+  app.range.tiles = { 2 }
+  app.command.MoveTiles{ before=1 }
+  expect_eq(imgs[2], ts:getTile(1))
+  expect_eq(imgs[1], ts:getTile(2))
+  expect_eq(imgs[3], ts:getTile(3))
+  expect_eq(imgs[4], ts:getTile(4))
+  expect_eq(1, #app.range.tiles)
+  expect_eq(1, app.range.tiles[1])
+  app.undo()
+
+  -- Move tiles 1 and 2 before 4, result=0,3,1,2,4
+  app.range.tiles = { 1, 2 }
+  app.command.MoveTiles({ before=4 })
+  expect_eq(imgs[3], ts:getTile(1))
+  expect_eq(imgs[1], ts:getTile(2))
+  expect_eq(imgs[2], ts:getTile(3))
+  expect_eq(imgs[4], ts:getTile(4))
+  expect_eq(2, #app.range.tiles)
+  expect_eq(2, app.range.tiles[1])
+  expect_eq(3, app.range.tiles[2])
+  app.undo()
+
+  -- Move tiles 1 and 3 before 3, result=0,2,1,3,4
+  app.range.tiles = { 1, 3 }
+  app.command.MoveTiles({ before=3 })
+  expect_eq(imgs[2], ts:getTile(1))
+  expect_eq(imgs[1], ts:getTile(2))
+  expect_eq(imgs[3], ts:getTile(3))
+  expect_eq(imgs[4], ts:getTile(4))
+  expect_eq(2, #app.range.tiles)
+  expect_eq(2, app.range.tiles[1])
+  expect_eq(3, app.range.tiles[2])
+  app.undo()
+
+  -- Copy tiles 1 before 1, result=0,1,1,2,3,4
+  app.range.tiles = { 1 }
+  app.command.CopyTiles({ before=1 })
+  expect_eq(1, #app.range.tiles)
+  expect_eq(1, app.range.tiles[1])
+  expect_eq(6, #ts)
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[1]))
+  assert(ts:getTile(2):isEqual(imgs[1]))
+  assert(ts:getTile(3):isEqual(imgs[2]))
+  assert(ts:getTile(4):isEqual(imgs[3]))
+  assert(ts:getTile(5):isEqual(imgs[4]))
+  app.undo()
+
+  -- Copy tiles 1 before 4, result=0,1,2,3,1,4
+  app.range.tiles = { 1 }
+  app.command.CopyTiles({ before=4 })
+  expect_eq(1, #app.range.tiles)
+  expect_eq(4, app.range.tiles[1])
+  expect_eq(6, #ts)
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[1]))
+  assert(ts:getTile(2):isEqual(imgs[2]))
+  assert(ts:getTile(3):isEqual(imgs[3]))
+  assert(ts:getTile(4):isEqual(imgs[1]))
+  assert(ts:getTile(5):isEqual(imgs[4]))
+  app.undo()
+
+  -- Copy tiles 1, 2, and 4, before 5, result=0,1,2,3,4,1,2,4
+  app.range.tiles = { 1, 2, 4 }
+  app.command.CopyTiles({ before=5 })
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[1]))
+  assert(ts:getTile(2):isEqual(imgs[2]))
+  assert(ts:getTile(3):isEqual(imgs[3]))
+  assert(ts:getTile(4):isEqual(imgs[4]))
+  assert(ts:getTile(5):isEqual(imgs[1]))
+  assert(ts:getTile(6):isEqual(imgs[2]))
+  assert(ts:getTile(7):isEqual(imgs[4]))
+  app.undo()
+
+  -- Copy tiles 2, and 4, before 1, result=0,2,4,1,2,3,4
+  app.range.tiles = { 2, 4 }
+  app.command.CopyTiles({ before=1 })
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[2]))
+  assert(ts:getTile(2):isEqual(imgs[4]))
+  assert(ts:getTile(3):isEqual(imgs[1]))
+  assert(ts:getTile(4):isEqual(imgs[2]))
+  assert(ts:getTile(5):isEqual(imgs[3]))
+  assert(ts:getTile(6):isEqual(imgs[4]))
+  app.undo()
+
+  -- Copy tiles 1, and 4, before 5, result=0,1,2,3,4,1,4
+  app.range.tiles = { 1, 4 }
+  app.command.CopyTiles({ before=5 })
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[1]))
+  assert(ts:getTile(2):isEqual(imgs[2]))
+  assert(ts:getTile(3):isEqual(imgs[3]))
+  assert(ts:getTile(4):isEqual(imgs[4]))
+  assert(ts:getTile(5):isEqual(imgs[1]))
+  assert(ts:getTile(6):isEqual(imgs[4]))
+  app.undo()
+
+  -- Copy tiles 1, and 4, before 6, result=0,1,2,3,4,-,1,4
+  app.range.tiles = { 1, 4 }
+  app.command.CopyTiles({ before=6 })
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[1]))
+  assert(ts:getTile(2):isEqual(imgs[2]))
+  assert(ts:getTile(3):isEqual(imgs[3]))
+  assert(ts:getTile(4):isEqual(imgs[4]))
+  assert(ts:getTile(5):isEmpty())
+  assert(ts:getTile(6):isEqual(imgs[1]))
+  assert(ts:getTile(7):isEqual(imgs[4]))
+  app.undo()
+
+  -- Copy tiles 3, and 4, before 8, result=0,1,2,3,4,-,-,-,3,4
+  app.range.tiles = { 3, 4 }
+  app.command.CopyTiles({ before=8 })
+  assert(ts:getTile(0):isEmpty())
+  assert(ts:getTile(1):isEqual(imgs[1]))
+  assert(ts:getTile(2):isEqual(imgs[2]))
+  assert(ts:getTile(3):isEqual(imgs[3]))
+  assert(ts:getTile(4):isEqual(imgs[4]))
+  assert(ts:getTile(5):isPlain())
+  assert(ts:getTile(6):isPlain())
+  assert(ts:getTile(7):isPlain())
+  assert(ts:getTile(8):isEqual(imgs[3]))
+  assert(ts:getTile(9):isEqual(imgs[4]))
+  app.undo()
+
+end
+
+----------------------------------------------------------------------
+-- Tests bug with alpha=0 and different RGB values
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 32)
+  spr.gridBounds = Rectangle(0, 0, 2, 2)
+  app.command.NewLayer{ tilemap=true }
+
+  local tm = app.activeLayer
+  local ts = tm.tileset
+  expect_eq(1, #ts)
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=0, b=0, a=255 },
+    tilemapMode=TilesetMode.PIXELS,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0), Point(3, 0) }}
+
+  expect_eq(2, #ts)
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0, a=0 },
+    tilemapMode=TilesetMode.PIXELS,
+    tilesetMode=TilesetMode.STACK,
+    points={ Point(0, 0), Point(1, 0) }}
+
+  -- If #ts is == 3, it means that the last useTool() with a r=255 a=0
+  -- created a new tile, that shouldn't be the case (because a=0
+  -- should ignore RGB values to compare tiles)
+  expect_eq(2, #ts)
+
+end
+
+----------------------------------------------------------------------
+-- Tests tiles dissapearing in AUTO mode
+----------------------------------------------------------------------
+
+do
+  local spr = Sprite(32, 16, ColorMode.INDEXED)
+  spr.gridBounds = Rectangle(0, 0, 2, 2)
+  app.command.ConvertLayer{ to="tilemap" }
+  app.useTool{ points={ Point(0, 0), Point(31, 31) }, color=1, tool="filled_ellipse", tilesetMode=TilesetMode.AUTO }
+  app.useTool{ points={ Point(4, 4), Point(27, 27) }, color=2, tool="filled_ellipse", tilesetMode=TilesetMode.AUTO }
+  app.useTool{ points={ Point(0, 0), Point(32, 16) }, color=3, tool="line", tilesetMode=TilesetMode.AUTO }
+  app.useTool{ points={ Point(0, 0), Point(31, 8),
+                        Point(0, 8), Point(31, 16) },
+               brush=4, color=3, tool="pencil", tilesetMode=TilesetMode.AUTO }
+
+  local i = spr.cels[1].image
+  assert(i:getPixel(4, 6) ~= 0)
+  assert(i:getPixel(8, 7) ~= 0)
+end
+
+-----------------------------------------------------------------------
+-- Test CanvasSize with tilemaps when we trim out content
+-----------------------------------------------------------------------
+
+do
+  local sprite = Sprite(32, 32)
+  sprite.gridBounds = Rectangle(0, 0, 16, 16)
+
+  -- Create a 2x2 tilemap with 4 tiles drawing an ellipse
+  app.command.NewLayer{ tilemap=true }
+  app.useTool{
+    tool='filled_ellipse',
+    color=Color{ r=255, g=255, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(0, 0), Point(31, 31) }
+  }
+  assert(#sprite.layers == 2)
+  -- remove the unused layer image
+  sprite:deleteLayer("Layer 1")
+  assert(#sprite.layers == 1)
+
+  local celMap = app.activeLayer.cels[1]
+  assert(celMap.bounds == Rectangle(0, 0, 32, 32))
+
+  -- resize the canvas to 16x16 starting point(4,9)
+  -- covering a large part of the tile in 0,0
+  app.command.CanvasSize{
+    bounds=Rectangle(4,9,16,16),
+    trimOutside=true
+  }
+
+  assert(#app.activeLayer.cels == 1)
+
+  expect_eq(celMap.bounds, Rectangle(-4, -9, 32, 32))
+  expect_eq(sprite.bounds.width, 16)
+  expect_eq(sprite.bounds.height, 16)
+
+  -- grid is 16x16, so expected image width/height is 2
+  expect_eq(celMap.image.width, 2)
+  expect_eq(celMap.image.height, 2)
+  expect_eq(celMap.image:getPixel(0,0), 1)
+  expect_eq(celMap.image:getPixel(1,0), 2)
+  expect_eq(celMap.image:getPixel(0,1), 3)
+  expect_eq(celMap.image:getPixel(1,1), 4)
+
+  -- undo the last canvas resize
+  app.command.Undo()
+
+  -- reposition the cel in the sprite
+  celMap.position = Point(0,16)
+  expect_eq(celMap.bounds, Rectangle(0, 16, 32, 32))
+
+  -- deleting the whole tilemap cel when it's outside the bounds
+  app.command.CanvasSize {
+    bounds=Rectangle(0,0,8,8),
+    trimOutside=true
+  }
+
+  expect_eq(#app.activeLayer.cels, 0)
+  expect_eq(sprite.bounds.width, 8)
+  expect_eq(sprite.bounds.height, 8)
+
+  -- undo canvas resize
+  app.command.Undo()
+
+  -- undo set position
+  app.command.Undo()
+  expect_eq(celMap.bounds, Rectangle(0, 0, 32, 32))
+
+  app.command.CanvasSize{
+    bounds=Rectangle(16,16,16,16),
+    trimOutside=true
+  }
+
+  assert(celMap ~= nil)
+  expect_eq(celMap.bounds.x, 0)
+  expect_eq(celMap.bounds.y, 0)
+  expect_eq(celMap.image.width, 1)
+  expect_eq(celMap.image.height, 1)
+  expect_eq(celMap.position, Point(0,0))
+  expect_eq(celMap.image:getPixel(0,0), 4)
+end
+
+-----------------------------------------------------------------------
+-- Test CanvasSize when the bounds of an image is shrunken
+-----------------------------------------------------------------------
+
+do
+  local sprite = Sprite(32, 32)
+  sprite.gridBounds = Rectangle(0, 0, 8, 8)
+
+  app.command.NewLayer{ tilemap=true }
+  local tilemapLayer = sprite.layers[2]
+
+  -- tile 1
+  app.useTool {
+    tool='pencil', color=Color{r=255, b=0, g=255},
+    layer=tilemapLayer,
+    points={ Point(7,8), Point(0, 15) },
+    tilesetMode=TilesetMode.AUTO
+  }
+
+  local celMap = tilemapLayer.cels[1]
+
+  -- tile 2
+  app.useTool {
+    tool='pencil', color=Color{r=0, b=255, g=255},
+    cel=celMap,
+    points={ Point(24,16), Point(31, 23) },
+    tilesetMode=TilesetMode.AUTO
+  }
+
+  -- tile 3
+  app.useTool {
+    tool='pencil', color=Color{r=0, b=0, g=255},
+    cel=celMap,
+    points={ Point(30,24), Point(24, 31) },
+    tilesetMode=TilesetMode.AUTO
+  }
+
+  -- tile 4
+  app.useTool {
+    tool='pencil', color=Color{r=0, b=255, g=0},
+    cel=celMap,
+    points={ Point(17,24), Point(23, 31) },
+    tilesetMode=TilesetMode.AUTO
+  }
+
+  -- crop this sprite a little below pixel(0,0)
+  app.command.CanvasSize {
+    bounds=Rectangle(8,16,20,16),
+    trimOutside=true, ui=false
+  }
+
+  expect_eq(sprite.bounds.width, 20)
+  expect_eq(sprite.bounds.height, 16)
+
+  -- ideally, we expect a 3x2 image, however, some parts of top and left
+  -- of the image are empty/notile, so it's optimized by shrunking it
+  -- we got paddings instead.
+
+  expect_eq(celMap.position, Point(8, 0))
+  expect_eq(celMap.image.width, 2)
+  expect_eq(celMap.image.height, 2)
+  expect_eq(celMap.image:getPixel(0, 0), 0)
+  expect_eq(celMap.image:getPixel(1, 0), 2)
+  expect_eq(celMap.image:getPixel(1, 1), 3)
+  expect_eq(celMap.image:getPixel(0, 1), 4)
+end
+
+----------------------------------------------------------------------
+-- Tests canvas resizing in the tilemap with tiles 1x1
+----------------------------------------------------------------------
+
+do
+  local sprite1 = Sprite(4, 4)
+  -- Create a tilemap layer which grid size is 1x1
+  sprite1.gridBounds = Rectangle(1, 1, 1, 1)
+  app.command.NewLayer{ tilemap=true }
+  -- Create a tilemap of 2x2 tiles:
+  --   ______
+  --  |  ∏∏  |
+  --  |  ∏∏  |
+  --  |      |
+  --  |______|
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(1, 0) }
+  }
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=255, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(2, 0) }
+  }
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=0, b=255 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(1, 1) }
+  }
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=255, b=255 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(2, 1) }
+  }
+
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(0,0,2,2),
+    trimOutside=true
+  }
+
+  local cel = app.activeLayer.cels[1]
+  expect_eq(cel.image.width, 1)
+  expect_eq(cel.image.height, 2)
+  expect_eq(cel.bounds, Rectangle(1, 0, 1, 2))
+
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(0,0,2,1),
+    trimOutside=true
+  }
+
+  cel = app.activeLayer.cels[1]
+  expect_eq(cel.image.width, 1)
+  expect_eq(cel.image.height, 1)
+  expect_eq(cel.bounds, Rectangle(1, 0, 1, 1))
+end
+
+----------------------------------------------------------------------
+-- Tests canvas resizing in the tilemap with tiles 2x2, origin 2,1
+----------------------------------------------------------------------
+
+do
+  local sprite2 = Sprite(8, 8)
+  -- Create a tilemap layer which grid size is 2x2
+  sprite2.gridBounds = Rectangle(0, 0, 2, 2)
+  app.command.NewLayer{ tilemap=true }
+  -- Create a tilemap of 4x4 tiles:
+  --
+  --        ,--------- x = 2
+  --       |
+  --   ____v______
+  --  |           |
+  --  |    ∏∏XX   |<-- y = 1
+  --  |    ∏∏XX   |
+  --  |    OO∏∏   |
+  --  |    OO∏∏   |
+  --  |           |
+  --  |           |
+  --  |___________|
+
+  -- Making a pixel to make a Cel
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(0, 0) }
+  }
+
+  -- Moving the Cel to de desired position
+  app.activeLayer.cels[1].position = Point(2, 1)
+
+  -- Filling with squares of 2x2
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(3, 1), Point(3, 2), Point(2, 2) }
+  }
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=255, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(4, 1), Point(5, 1), Point(5, 2), Point(4, 2) }
+  }
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=0, b=255 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(2, 3), Point(3, 3), Point(3, 4), Point(2, 4) }
+  }
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=255, b=255 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(4, 3), Point(5, 3), Point(5, 4), Point(4, 4) }
+  }
+
+  -- ======================================================================
+  -- Cutting the canvas in the midle of the tilemap:
+  --
+  --       ,--------- x = -1
+  --      |
+  --   ___v _______
+  --  |    |  |    |
+  --      ∏|∏X|X    <-- y = -1
+  --  |----|--|----|
+  --      ∏|∏X|X
+  --      O|O∏|∏
+  --  |----|--|----|
+  --      O|O∏|∏
+  --       |  |
+  --       |  |
+  --  |____|__|____|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(3,2,2,2),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(-1,-1))
+  expect_eq(app.activeLayer.cels[1].image.width, 2) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 2) -- height in tilemap terms
+  -- ======================================================================
+
+  app.command.Undo()
+
+  -- ======================================================================
+  -- Cutting the canvas from the bottom
+  --        ,--------- x = 2
+  --       |
+  --   ____v______
+  --  |           |
+  --  |    ∏∏XX   |<-- y = 1
+  --  |    ∏∏XX   |
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(0,0,8,3),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(2,1))
+  expect_eq(app.activeLayer.cels[1].image.width, 2) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 1) -- height in tilemap terms
+  -- ======================================================================
+  -- Cutting the canvas from the right
+  --        ,--------- x = 2
+  --       |
+  --   ____v_
+  --  |      |
+  --  |    ∏∏|<-- y = 1
+  --  |    ∏∏|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(0,0,4,3),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(2,1))
+  expect_eq(app.activeLayer.cels[1].image.width, 1) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 1) -- height in tilemap terms
+  -- ======================================================================
+
+  app.command.Undo()
+  app.command.Undo()
+
+  -- ======================================================================
+  -- Cutting the canvas from the left, partial tile:
+  --
+  --       ,--------- x = -1
+  --      |
+  --      v ______
+  --  |    |      |
+  --  |   ∏|∏XX   |<-- y = 1
+  --  |   ∏|∏XX   |
+  --  |   O|O∏∏   |
+  --  |   O|O∏∏   |
+  --  |    |      |
+  --  |    |      |
+  --  |    |______|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(3,0,5,8),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(-1, 1))
+  expect_eq(app.activeLayer.cels[1].image.width, 2) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 2) -- height in tilemap terms
+  -- ======================================================================
+
+  app.command.Undo()
+
+  -- ======================================================================
+  -- Cutting the canvas from the top, partial tile:
+  --
+  --        ,--------- x = 2
+  --       |
+  --   ____|______
+  --       v
+  --   ____∏∏XX___ <-- y = -1
+  --  |    ∏∏XX   |
+  --  |    OO∏∏   |
+  --  |    OO∏∏   |
+  --  |           |
+  --  |           |
+  --  |___________|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(0,2,8,6),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(2, -1))
+  expect_eq(app.activeLayer.cels[1].image.width, 2) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 2) -- height in tilemap terms
+
+  -- ======================================================================
+
+  app.command.Undo()
+
+  -- ======================================================================
+  -- Cutting the canvas from the left, cutting first tile column:
+  --
+  --         ,--------- x = 0
+  --         |
+  --         v____
+  --  |     |     |
+  --  |     |XX   |<-- y = 1
+  --  |     |XX   |
+  --  |     |∏∏   |
+  --  |     |∏∏   |
+  --  |     |     |
+  --  |     |     |
+  --  |     |_____|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(4,0,4,8),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(0, 1))
+  expect_eq(app.activeLayer.cels[1].image.width, 1) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 2) -- height in tilemap terms
+  -- ======================================================================
+
+  app.command.Undo()
+
+  -- ======================================================================
+  -- Cutting the canvas from the top, cutting the top tile row:
+  --
+  --        ,--------- x = 2
+  --       |
+  --   ____|______
+  --       |
+  --       |
+  --   ____v______
+  --  |    OO∏∏   | <-- y = 0
+  --  |    OO∏∏   |
+  --  |           |
+  --  |           |
+  --  |___________|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(0,3,8,5),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(2, 0))
+  expect_eq(app.activeLayer.cels[1].image.width, 2) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 1) -- height in tilemap terms
+end
+
+----------------------------------------------------------------------
+-- Tests canvas resizing in the tilemap with tiles 2x2 with shrink action
+----------------------------------------------------------------------
+
+do
+  local sprite3 = Sprite(8, 8)
+  -- Create a tilemap layer which grid size is 2x2
+  sprite3.gridBounds = Rectangle(0, 0, 2, 2)
+  app.command.NewLayer{ tilemap=true }
+  -- Create a tilemap of 4x4 tiles:
+  --
+  --    ,--------- x = 0
+  --   |
+  --   v__________
+  --  |           |
+  --  |∏∏         |<-- y = 1
+  --  |∏∏         |
+  --  |OO       XX|
+  --  |OO       XX|
+  --  |         ∏∏|
+  --  |         ∏∏|
+  --  |___________|
+
+  -- Making a pixel to make a Cel
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(0, 0) }
+  }
+
+  -- Moving the Cel to de desired position
+  app.activeLayer.cels[1].position = Point(0, 1)
+
+  -- Filling with squares of 2x2
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=0, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(1, 1), Point(1, 2), Point(0, 2) }
+  }
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=255, b=0 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(0, 3), Point(1, 3), Point(1, 4), Point(0, 4) }
+  }
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=0, g=0, b=255 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(6, 3), Point(7, 3), Point(6, 4), Point(7, 4) }
+  }
+
+  app.useTool{
+    tool='pencil',
+    color=Color{ r=255, g=255, b=255 },
+    tilesetMode=TilesetMode.AUTO,
+    points={ Point(6, 5), Point(7, 5), Point(6, 6), Point(7, 6) }
+  }
+
+  -- ======================================================================
+  -- Cutting the canvas from the left, cutting the most left tile column:
+  --
+  --             ,--------- x = 4
+  --            |
+  --      ______v_
+  --  |  |        |
+  --  |  |        |
+  --  |  |        |
+  --  |  |      XX| <-- y = 3
+  --  |  |      XX|
+  --  |  |      ∏∏|
+  --  |  |      ∏∏|
+  --  |  |________|
+  app.command.CanvasSize{
+    ui=false,
+    bounds=Rectangle(2,0,6,8),
+    trimOutside=true
+  }
+
+  expect_eq(app.activeLayer.cels[1].position, Point(4, 3))
+  expect_eq(app.activeLayer.cels[1].image.width, 1) -- width in tilemap terms
+  expect_eq(app.activeLayer.cels[1].image.height, 2) -- height in tilemap terms
+end
diff --git a/tests/scripts/tools.lua b/tests/scripts/tools.lua
new file mode 100644
index 000000000..ee64aa3b2
--- /dev/null
+++ b/tests/scripts/tools.lua
@@ -0,0 +1,684 @@
+-- Copyright (C) 2019-2020  Igara Studio S.A.
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+dofile('./test_utils.lua')
+
+local rgba = app.pixelColor.rgba
+local gray = app.pixelColor.graya
+
+----------------------------------------------------------------------
+-- activeTool
+----------------------------------------------------------------------
+
+local pencil = app.activeTool -- pencil is the default tool
+assert(pencil ~= nil)
+assert(pencil.id == 'pencil')
+app.activeTool = 'line'
+assert(app.activeTool.id == 'line')
+app.activeTool = pencil
+assert(app.activeTool.id == 'pencil')
+
+-- default brush is a circle of 1x1 when there is no UI
+assert(app.activeBrush.type == BrushType.CIRCLE)
+assert(app.activeBrush.size == 1)
+assert(app.activeBrush.angle == 0)
+
+----------------------------------------------------------------------
+-- create sprite for testing
+----------------------------------------------------------------------
+
+local spr = Sprite(4, 4)
+local cel = spr.cels[1]
+expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+
+----------------------------------------------------------------------
+-- pencil and eraser
+----------------------------------------------------------------------
+
+app.useTool{
+  tool='pencil',
+  color=Color{ r=0, g=0, b=0 },
+  points={ Point(2, 2),
+           Point(3, 2) }}
+expect_eq(cel.bounds, Rectangle(2, 2, 2, 1))
+
+app.useTool{
+  tool='eraser',
+  points={ Point(2, 2) }}
+expect_eq(cel.bounds, Rectangle(3, 2, 1, 1))
+
+app.useTool{
+  tool='eraser',
+  points={ Point(3, 2) }}
+-- This must fail because cel is pointing to an invalid cel now.
+-- TODO: In a future this could change if this issue:
+--         https://github.com/aseprite/aseprite/issues/1833
+--       is implemented.
+assert(not pcall(function() print(cel.bounds) end))
+
+----------------------------------------------------------------------
+-- line
+----------------------------------------------------------------------
+
+local red = Color{ r=255, g=0, b=0 }
+app.useTool{
+  tool='line',
+  color=red,
+  points={ Point(0, 0), Point(3, 3) }}
+local cel = spr.cels[1]
+expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+do
+  local r = red.rgbaPixel
+  local expected = { r, 0, 0, 0,
+                     0, r, 0, 0,
+                     0, 0, r, 0,
+                     0, 0, 0, r }
+  assert(cel.image.width == 4)
+  assert(cel.image.height == 4)
+  for v=0,3 do
+    for u=0,3 do
+      assert(cel.image:getPixel(u, v) == expected[1+v*4+u])
+    end
+  end
+end
+
+----------------------------------------------------------------------
+-- paint_bucket
+----------------------------------------------------------------------
+
+app.useTool{
+  tool='paint_bucket',
+  color=red,
+  points={ Point(3, 0) }}
+local cel = spr.cels[1]
+do
+  local r = red.rgbaPixel
+  local expected = { r, r, r, r,
+                     0, r, r, r,
+                     0, 0, r, r,
+                     0, 0, 0, r }
+  assert(cel.image.width == 4)
+  assert(cel.image.height == 4)
+  for v=0,3 do
+    for u=0,3 do
+      assert(cel.image:getPixel(u, v) == expected[1+v*4+u])
+    end
+  end
+end
+
+----------------------------------------------------------------------
+-- rectangle
+----------------------------------------------------------------------
+
+local blue = Color{ r=0, g=0, b=255 }
+app.useTool{
+  tool='rectangle',
+  color=blue,
+  points={ Point(0, 0), Point(3, 3) }}
+local cel = spr.cels[1]
+do
+  local r = red.rgbaPixel
+  local b = blue.rgbaPixel
+  local expected = { b, b, b, b,
+                     b, r, r, b,
+                     b, 0, r, b,
+                     b, b, b, b }
+  assert(cel.image.width == 4)
+  assert(cel.image.height == 4)
+  for v=0,3 do
+    for u=0,3 do
+      assert(cel.image:getPixel(u, v) == expected[1+v*4+u])
+    end
+  end
+end
+
+----------------------------------------------------------------------
+-- ellipse
+----------------------------------------------------------------------
+
+local yellow = Color{ r=255, g=255, b=0 }
+app.useTool{
+  tool='ellipse',
+  color=yellow,
+  points={ Point(0, 0), Point(3, 3) }}
+local cel = spr.cels[1]
+do
+  local r = red.rgbaPixel
+  local b = blue.rgbaPixel
+  local y = yellow.rgbaPixel
+  local expected = { b, y, y, b,
+                     y, r, r, y,
+                     y, 0, r, y,
+                     b, y, y, b }
+  assert(cel.image.width == 4)
+  assert(cel.image.height == 4)
+  for v=0,3 do
+    for u=0,3 do
+      assert(cel.image:getPixel(u, v) == expected[1+v*4+u])
+    end
+  end
+end
+
+----------------------------------------------------------------------
+-- draw in several cels
+----------------------------------------------------------------------
+
+do
+  local spr2 = Sprite(4, 4)
+  spr2:newFrame()
+
+  local bgLay = spr2.layers[1]
+  local fgLay = spr2:newLayer()
+  local bgCel1 = spr2:newCel(fgLay, 1, Image(spr2.spec))
+  local fgCel1 = spr2:newCel(bgLay, 1, Image(spr2.spec))
+  local bgCel2 = spr2:newCel(fgLay, 2, Image(spr2.spec))
+  local fgCel2 = spr2:newCel(bgLay, 2, Image(spr2.spec))
+  expect_eq(fgCel1.bounds, Rectangle(0, 0, 4, 4))
+  expect_eq(bgCel1.bounds, Rectangle(0, 0, 4, 4))
+  expect_eq(fgCel2.bounds, Rectangle(0, 0, 4, 4))
+  expect_eq(bgCel2.bounds, Rectangle(0, 0, 4, 4))
+
+  -- After each useTool(), the cels will be shrunken to the minimum
+  -- required size.
+  app.activeTool = 'pencil'
+  app.useTool{ color=red, cel=bgCel1, points={ Point(0, 0) }}
+  app.useTool{ color=red, layer=bgCel2.layer, frame=bgCel2.frame, points={ Point(1, 0) }}
+
+  -- After using the tool in bgCel2, the activeFrame is the frame
+  -- number 2.
+  assert(bgCel2.frame == app.activeFrame)
+  assert(bgCel2.frame == fgCel2.frame)
+
+  app.activeFrame = fgCel1.frame
+  app.useTool{ color=yellow, layer=fgCel1.layer, points={ Point(1, 1) }}
+  app.useTool{ color=yellow, cel=fgCel2, points={ Point(2, 1) }}
+
+  expect_eq(bgCel1.bounds, Rectangle(0, 0, 1, 1))
+  expect_eq(bgCel2.bounds, Rectangle(1, 0, 1, 1))
+  expect_eq(fgCel1.bounds, Rectangle(1, 1, 1, 1))
+  expect_eq(fgCel2.bounds, Rectangle(2, 1, 1, 1))
+
+  assert(bgCel1.image:getPixel(0, 0) == red.rgbaPixel)
+  assert(bgCel2.image:getPixel(0, 0) == red.rgbaPixel)
+  assert(fgCel1.image:getPixel(0, 0) == yellow.rgbaPixel)
+  assert(fgCel2.image:getPixel(0, 0) == yellow.rgbaPixel)
+end
+
+----------------------------------------------------------------------
+-- draw with brushes
+----------------------------------------------------------------------
+
+function drawing_with_simple_brushes(colorMode, a, b, c)
+  print("drawing_with_simple_brushes", colorMode)
+
+  local expectedImages = {
+    { 0, 0, 0, 0,
+      0, 0, 0, 0,
+      0, 0, 0, 0,
+      0, 0, 0, 0 },
+    { 0, 0, 0, 0,
+      0, a, 0, 0,
+      0, 0, 0, 0,
+      0, 0, 0, 0 },
+    { 0, 0, 0, 0,
+      0, b, b, 0,
+      0, b, b, 0,
+      0, 0, 0, 0 },
+    { c, c, c, 0,
+      c, c, c, c,
+      c, c, c, c,
+      0, c, c, c }
+  }
+
+  local s = Sprite(4, 4, colorMode)
+  assert(s == app.activeSprite)
+  assert(s.cels[1] == app.activeCel)
+
+  function expect_cel_is_image(imageIndex)
+    local a = Image(s.spec)
+    a:drawSprite(s, 1, Point(0, 0))
+    local b = expectedImages[imageIndex]
+    expect_img(a, b)
+  end
+
+  expect_cel_is_image(1)
+  app.useTool{ tool='pencil', color=a, points={ Point(1, 1) } }
+  assert(#s.cels == 1)
+  expect_cel_is_image(2)
+  app.undo()
+
+  expect_cel_is_image(1)
+  app.useTool{ tool='pencil',
+               brush=Brush{ size=2, type=BrushType.SQUARE },
+               color=b, points={ Point(2, 2) } }
+  expect_cel_is_image(3)
+  app.undo()
+
+  expect_cel_is_image(1)
+  app.useTool{ tool='pencil',
+               brush=Brush{ size=2, type=BrushType.SQUARE, center=Point(0, 0) },
+               color=b, points={ Point(1, 1) } }
+  expect_cel_is_image(3)
+  app.undo()
+
+  expect_cel_is_image(1)
+  app.useTool{ tool='line',
+               brush={ size=3, type=BrushType.SQUARE },
+               color=c, points={ Point(1, 1), Point(2, 2) } }
+  expect_cel_is_image(4)
+  app.undo()
+
+end
+
+do
+  drawing_with_simple_brushes(ColorMode.RGB, red.rgbaPixel, blue.rgbaPixel, yellow.rgbaPixel)
+  drawing_with_simple_brushes(ColorMode.GRAY, gray(255), gray(128), gray(32))
+  drawing_with_simple_brushes(ColorMode.INDEXED, 1, 2, 3)
+end
+
+----------------------------------------------------------------------
+-- draw with special image brushes + patterns
+----------------------------------------------------------------------
+
+function drawing_with_image_brushes(imageColorMode, colorInImage,
+                                    brushColorMode, colorInBrush, palette)
+  print("drawing_with_image_brushes", imageColorMode, brushColorMode)
+  local s = Sprite(4, 4, imageColorMode)
+  local c = colorInImage
+  cel = s.cels[1]
+
+  if palette then
+    s:setPalette(palette)
+  end
+
+  -- Brush image with BrushPattern.ORIGIN
+  local bi = Image(2, 2, brushColorMode)
+  bi:clear(0)
+  bi:putPixel(0, 0, colorInBrush)
+  bi:putPixel(1, 1, colorInBrush)
+  local b = Brush { image=bi,
+                    center=Point(0, 0),
+                    pattern=BrushPattern.ORIGIN,
+                    patternOrigin=Point(0, 0) }
+
+  expect_img(app.activeImage,
+             { 0, 0, 0, 0,
+               0, 0, 0, 0,
+               0, 0, 0, 0,
+               0, 0, 0, 0 })
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(0, 0) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 2, 2))
+  expect_img(app.activeImage,
+             { c, 0,
+               0, c })
+  app.undo()
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(0, 0), Point(1, 1) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 3, 3))
+  expect_img(app.activeImage,
+             { c, 0, 0,
+               0, c, 0,
+               0, 0, c })
+  app.undo()
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(0, 1) } }
+  expect_eq(cel.bounds, Rectangle(0, 1, 2, 2))
+  expect_img(app.activeImage,
+             { 0, c,
+               c, 0 })
+  app.undo()
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(0, 0), Point(2, 0),
+                                              Point(0, 0), Point(0, 1) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 3))
+  expect_img(app.activeImage,
+             { c, 0, c, 0,
+               0, c, 0, c,
+               c, 0, 0, 0 })
+  app.undo()
+
+  app.useTool{ tool='paint_bucket', brush=b, points={ Point(0, 0) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 4, 4))
+  expect_img(app.activeImage,
+             { c, 0, c, 0,
+               0, c, 0, c,
+               c, 0, c, 0,
+               0, c, 0, c })
+  app.undo()
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 0) } }
+  assert(app.activeImage ~= nil)
+  expect_eq(cel.bounds, Rectangle(1, 0, 2, 2))
+  expect_img(app.activeImage,
+             { 0, c,
+               c, 0 })
+  app.undo()
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 0),
+                                              Point(1, 0)} }
+  assert(app.activeImage ~= nil)
+  expect_eq(cel.bounds, Rectangle(1, 0, 2, 2))
+  expect_img(app.activeImage,
+             { 0, c,
+               c, 0 })
+  app.undo()
+
+  -- Change brush pattern to BrushPattern.TARGET
+
+  b = Brush { image=bi,
+              center=Point(0, 0),
+              pattern=BrushPattern.TARGET,
+              patternOrigin=Point(0, 0) }
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 0) } }
+  expect_eq(cel.bounds, Rectangle(1, 0, 2, 2))
+  expect_img(app.activeImage,
+             { c, 0,
+               0, c })
+  app.undo()
+
+end
+
+do
+  drawing_with_image_brushes(ColorMode.RGB, rgba(255, 0, 0),
+                             ColorMode.RGB, rgba(255, 0, 0))
+end
+
+----------------------------------------------------------------------
+-- draw with symmetry
+----------------------------------------------------------------------
+
+function drawing_with_symmetry(imageColorMode, colorInImage,
+			       brushColorMode, colorInBrush, palette)
+  print("drawing_with_symmetry", imageColorMode, brushColorMode)
+  local s = Sprite(8, 3, imageColorMode)
+  local c = colorInImage
+  cel = s.cels[1]
+
+  if palette then
+    s:setPalette(palette)
+  end
+
+  -- Enable symmetry
+  local pref = app.preferences
+  local docPref = pref.document(s)
+  pref.symmetry_mode.enabled = true
+  docPref.symmetry.mode   = 1 -- TODO use SymmetryMode.HORIZONTAL when it's available
+  docPref.symmetry.x_axis = 4
+
+  expect_eq(cel.bounds, Rectangle(0, 0, 8, 3))
+  expect_img(cel.image,
+             { 0, 0, 0, 0, 0, 0, 0, 0,
+	       0, 0, 0, 0, 0, 0, 0, 0,
+	       0, 0, 0, 0, 0, 0, 0, 0 })
+
+  local b = Brush { size=1 }
+  app.fgColor = c
+  app.useTool{ tool=pencil, brush=b, points={ Point(0, 0) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 8, 1))
+  expect_img(cel.image,
+             { c, 0, 0, 0, 0, 0, 0, c })
+  app.undo()
+
+  app.useTool{ tool=pencil, brush=b, points={ Point(2, 0) } }
+  expect_eq(cel.bounds, Rectangle(2, 0, 4, 1))
+  expect_img(cel.image,
+             { c, 0, 0, c })
+  app.undo()
+
+  -- Brush size 2x2 center=(1,1)
+  b = Brush { size=2 }
+  assert(b.center.x == 1)
+  assert(b.center.y == 1)
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 1) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 8, 2))
+  expect_img(cel.image,
+             { c, c, 0, 0, 0, 0, c, c,
+               c, c, 0, 0, 0, 0, c, c })
+  app.undo()
+
+  -- Brush size 2x2 center=(0,0)
+  b = Brush { size=2, center=Point(0, 0) }
+  assert(b.center.x == 0)
+  assert(b.center.y == 0)
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 0) } }
+  expect_eq(cel.bounds, Rectangle(1, 0, 6, 2))
+  expect_img(cel.image,
+             { c, c, 0, 0, c, c,
+               c, c, 0, 0, c, c })
+  app.undo()
+
+  -- Brush size 3x3
+  b = Brush { size=3 }
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 1) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 8, 3))
+  expect_img(cel.image,
+             { 0, c, 0, 0, 0, 0, c, 0,
+	       c, c, c, 0, 0, c, c, c,
+               0, c, 0, 0, 0, 0, c, 0 })
+  app.undo()
+
+  -- Brush size 3x3
+  b = Brush { size=3, center=Point(1, 1) }
+  app.useTool{ tool=pencil, brush=b, points={ Point(2, 1) } }
+  expect_eq(cel.bounds, Rectangle(1, 0, 6, 3))
+  expect_img(cel.image,
+             { 0, c, 0, 0, c, 0,
+	       c, c, c, c, c, c,
+               0, c, 0, 0, c, 0 })
+  app.undo()
+
+  -- Brush size 4x4 center=(2,2)
+  b = Brush { size=4 }
+  assert(b.center.x == 2)
+  assert(b.center.y == 2)
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 1) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 8, 3))
+  expect_img(cel.image,
+             { c, c, c, 0, 0, c, c, c,
+               c, c, c, 0, 0, c, c, c,
+               c, c, 0, 0, 0, 0, c, c })
+  app.undo()
+
+  -- Brush size 4x4 center=(1,1)
+  b = Brush { size=4, center=Point(1, 1) }
+  app.useTool{ tool=pencil, brush=b, points={ Point(1, 0) } }
+  expect_eq(cel.bounds, Rectangle(0, 0, 8, 3))
+  expect_img(cel.image,
+             { c, c, c, c, c, c, c, c,
+               c, c, c, c, c, c, c, c,
+               0, c, c, 0, 0, c, c, 0 })
+  app.undo()
+
+  -- Odd symmetry
+  docPref.symmetry.x_axis = 4.5
+
+  b = Brush { size=1 }
+  app.useTool{ tool=pencil, brush=b, points={ Point(4, 0) } }
+  expect_eq(cel.bounds, Rectangle(4, 0, 1, 1))
+  expect_img(cel.image,
+             { c })
+  app.undo()
+
+  b = Brush { size=1 }
+  app.useTool{ tool=pencil, brush=b, points={ Point(3, 0) } }
+  expect_eq(cel.bounds, Rectangle(3, 0, 3, 1))
+  expect_img(cel.image,
+             { c, 0, c })
+  app.undo()
+
+  b = Brush { size=2 }
+  app.useTool{ tool=pencil, brush=b, points={ Point(2, 0) } }
+  expect_eq(cel.bounds, Rectangle(1, 0, 7, 1))
+  expect_img(cel.image,
+             { c, c, 0, 0, 0, c, c })
+  app.undo()
+
+end
+
+do
+  drawing_with_symmetry(ColorMode.RGB, rgba(255, 0, 0),
+			ColorMode.RGB, rgba(255, 0, 0))
+end
+
+----------------------------------------------------------------------
+-- useTool in a transaction
+----------------------------------------------------------------------
+
+do
+  local s = Sprite(2, 2)
+  local r = red.rgbaPixel
+  local y = yellow.rgbaPixel
+  app.fgColor = r
+
+  local cel = s.cels[1]
+  expect_img(cel.image, { 0, 0,
+                          0, 0 })
+  app.transaction(
+    function()
+      app.useTool{ tool=pencil,
+                   color=r, brush=Brush{ size=1 },
+                   points={ Point(0, 0) } }
+      app.useTool{ tool=pencil,
+                   color=y, brush=Brush{ size=1 },
+                   points={ Point(1, 1) } }
+    end)
+  expect_img(cel.image, { r, 0,
+                          0, y })
+  app.undo() -- Undo the whole transaction (two useTool grouped in one transaction)
+  expect_img(cel.image, { 0, 0,
+                          0, 0 })
+end
+
+----------------------------------------------------------------------
+-- draw with tiled mode + image brush
+-- test for: https://community.aseprite.org/t/tile-mode-glitch/1183
+----------------------------------------------------------------------
+
+function drawing_with_tiled_mode_and_image_brush()
+  print("drawing_with_tiled_mode_and_image_brush")
+  local spr = Sprite(8, 3, ColorMode.INDEXED)
+  local cel = spr.cels[1]
+
+  -- enable tiled mode
+  local pref = app.preferences
+  local docPref = pref.document(spr)
+  docPref.tiled.mode = 3 -- both
+
+  expect_img(cel.image,
+             { 0, 0, 0, 0, 0, 0, 0, 0,
+               0, 0, 0, 0, 0, 0, 0, 0,
+               0, 0, 0, 0, 0, 0, 0, 0 })
+
+  -- Create brush
+  local brushImg = Image(5, 2, ColorMode.INDEXED)
+  array_to_pixels({ 1, 2, 3, 2, 1,
+                    0, 1, 2, 1, 0 }, brushImg)
+  local bru = Brush { image=brushImg }
+
+  -- Without overflow
+  app.useTool{ tool=pencil, brush=bru, points={ Point(2, 1) } }
+  expect_img(cel.image,
+             { 1, 2, 3, 2, 1,
+               0, 1, 2, 1, 0 })
+  app.undo()
+
+  -- Overflow at the left-side
+  app.useTool{ tool=pencil, brush=bru, points={ Point(1, 1) } }
+  expect_img(cel.image,
+             { 2, 3, 2, 1, 0, 0, 0, 1,
+               1, 2, 1, 0, 0, 0, 0, 0 })
+  app.undo()
+
+  -- Overflow at the right-side
+  app.useTool{ tool=pencil, brush=bru, points={ Point(9, 1) } }
+  expect_img(cel.image,
+             { 2, 3, 2, 1, 0, 0, 0, 1,
+               1, 2, 1, 0, 0, 0, 0, 0 })
+  app.undo()
+
+  -- Overflow at the top
+  app.useTool{ tool=pencil, brush=bru, points={ Point(0, 0) } }
+  expect_img(cel.image,
+             { 2, 1, 0, 0, 0, 0, 0, 1,
+               0, 0, 0, 0, 0, 0, 0, 0,
+               3, 2, 1, 0, 0, 0, 1, 2 })
+  app.undo()
+
+  -- Overflow at the bottom
+  app.useTool{ tool=pencil, brush=bru, points={ Point(1, 3) } }
+  expect_img(cel.image,
+             { 1, 2, 1, 0, 0, 0, 0, 0,
+               0, 0, 0, 0, 0, 0, 0, 0,
+               2, 3, 2, 1, 0, 0, 0, 1 })
+  app.undo()
+
+  docPref.tiled.mode = 0 -- none (disable tiled mode)
+end
+drawing_with_tiled_mode_and_image_brush()
+
+----------------------------------------------------------------------
+-- countour with pixel perfect
+----------------------------------------------------------------------
+
+do
+  local s = Sprite(3, 3, ColorMode.INDEXED)
+  local i = app.activeImage
+  i:clear(1)
+  expect_img(i,
+             { 1, 1, 1,
+               1, 1, 1,
+               1, 1, 1 })
+  app.useTool{
+    tool='contour',
+    brush=Brush(1),
+    color=2,
+    freehandAlgorithm=1, -- 1=FreehandAlgorithm.PIXEL_PERFECT
+    points={ { 1, 1 }, { 2, 1 }, { 2, 2 }
+    }
+  }
+  expect_img(app.activeImage,
+             { 1, 1, 1,
+               1, 2, 1,
+               1, 1, 2 })
+
+  app.undo()
+
+  -- Test one pixel when using one point
+  app.useTool{
+    tool='contour',
+    brush=Brush(1),
+    color=2,
+    freehandAlgorithm=1, -- 1=FreehandAlgorithm.PIXEL_PERFECT
+    points={ { 1, 1 } }
+  }
+  expect_img(app.activeImage,
+             { 1, 1, 1,
+               1, 2, 1,
+               1, 1, 1 })
+  app.undo()
+
+  -- Test bug where one click doesn't draw with the contour tool with
+  -- pixel perfect algorith.
+  -- Report: https://community.aseprite.org/t/13149
+  expect_img(app.activeImage,
+             { 1, 1, 1,
+               1, 1, 1,
+               1, 1, 1 })
+  app.useTool{
+    tool='contour',
+    brush=Brush(1),
+    color=2,
+    freehandAlgorithm=1, -- 1=FreehandAlgorithm.PIXEL_PERFECT
+    -- Two points in the same spot, this happens in the UI, one
+    -- created in mouse down, other in mouse up.
+    points={ { 1, 1 }, { 1, 1 } }
+  }
+  expect_img(app.activeImage,
+             { 1, 1, 1,
+               1, 2, 1,
+               1, 1, 1 })
+end
diff --git a/tests/scripts/version.lua b/tests/scripts/version.lua
new file mode 100644
index 000000000..024b43b4b
--- /dev/null
+++ b/tests/scripts/version.lua
@@ -0,0 +1,41 @@
+-- Copyright (C) 2019-2021  Igara Studio S.A.
+-- Copyright (C) 2018  David Capello
+--
+-- This file is released under the terms of the MIT license.
+-- Read LICENSE.txt for more information.
+
+assert(string.sub(tostring(app.version), 1, 1) == "1")
+assert(string.sub(tostring(app.version), 2, 2) == ".")
+assert(app.version.major == 1)
+
+-- We cannot test the specific app.version from the "main" branch
+-- because it's "1.x-dev" (which is converted to "1.0-dev" as Version object)
+--assert(app.version > Version("1.2.10-beta4"))
+
+assert(Version("1") == Version("1"))
+assert(Version("1.1") > Version("1"))
+assert(Version("0.1") < Version("0.2"))
+assert(Version("1.0.1") > Version("1"))
+assert(Version("1.0.1") < Version("1.1"))
+assert(Version("1.0.1") == Version("1.0.1"))
+assert(Version("1.0.1") ~= Version("1.0.2"))
+assert(Version("1.0.1") > Version("1.0.1-beta"))
+assert(Version("1.0.1") > Version("1.0.1-dev"))
+assert(Version("1.0.1-beta") > Version("1.0.1-alpha"))
+assert(Version("1.0.1-beta50") < Version("1.0.1-beta100"))
+assert(Version("1.0.1-beta50") <= Version("1.0.1-beta100"))
+assert(Version("1.0.1-beta100") <= Version("1.0.1-beta100"))
+
+local v = Version()
+assert(v.major == 0)
+assert(v.minor == 0)
+assert(v.patch == 0)
+assert(v.prereleaseLabel == "")
+assert(v.prereleaseNumber == 0)
+
+v = Version("1.2.10-beta4")
+assert(v.major == 1)
+assert(v.minor == 2)
+assert(v.patch == 10)
+assert(v.prereleaseLabel == "beta")
+assert(v.prereleaseNumber == 4)
diff --git a/tests/sprites/1empty3.aseprite b/tests/sprites/1empty3.aseprite
new file mode 100644
index 000000000..c28079f68
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diff --git a/tests/sprites/2f-index-3x3.aseprite b/tests/sprites/2f-index-3x3.aseprite
new file mode 100644
index 000000000..55d2ce410
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diff --git a/tests/sprites/README.md b/tests/sprites/README.md
new file mode 100644
index 000000000..14dfd7245
--- /dev/null
+++ b/tests/sprites/README.md
@@ -0,0 +1,27 @@
+# Files
+
+* `abcd.aseprite`: Indexed, 32x32, four layers ("a", "b", "c", "d")
+* `1empty3.aseprite`: RGB, 32x32, two layers ("fg", "bg"), 2nd frame
+  completelly empty, two tags ("a", "b")
+* `groups2.aseprite`: Indexed, 8x8, two groups ("items", "player"),
+  two layers per group ("items/gun", "items/sword", "player/head",
+  "player/body"), with one layer hidden ("items/gun").
+* `groups3abc.aseprite`: RGB, 9x11, three groups ("a", "b", "c"), with
+  three layers each one (called "a", "b", "c" too). There is a
+  combination of visibilities ("b/b", "c", "c/a", and "c/b" are
+  hidden).
+* `bg-index-3.aseprite`: Indexed, 4x4, two layers ("fg" and "bg")
+  with a special transparent index color (= palette index 3).
+* `tags3.aseprite`: 3 tags ("forward", "reverse", "pingpong") and 3
+  layers ("a", "b", "c"), 4x4, several linked cels + layer "c" with
+  empty cels.
+* `point4frames.aseprite`: Indexed, 4 frames, 2 layers, same cel
+  content but different positions, can be used to test
+  `-merge-duplicates` to check if all cels go to the same sprite sheet
+  position.
+* `point2frames.aseprite`: Indexed, 2 frames, 1 layer, same cel
+  content as in `point4frames.aseprite`. Useful to test if
+  `"sourceSize"` is different when two cels from different sprites are
+  merged in the same texture atlas.
+* `2f-index-3x3.aseprite`: Indexed, 2 frames, 1 layer, mask color set
+  to index 21.
diff --git a/tests/sprites/abcd.aseprite b/tests/sprites/abcd.aseprite
new file mode 100644
index 000000000..6926af494
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diff --git a/tests/sprites/bg-index-3.aseprite b/tests/sprites/bg-index-3.aseprite
new file mode 100644
index 000000000..f36d2b499
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diff --git a/tests/sprites/groups2.aseprite b/tests/sprites/groups2.aseprite
new file mode 100644
index 000000000..4310c50f4
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diff --git a/tests/sprites/groups3abc.aseprite b/tests/sprites/groups3abc.aseprite
new file mode 100644
index 000000000..baced9349
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diff --git a/tests/sprites/link.aseprite b/tests/sprites/link.aseprite
new file mode 100644
index 000000000..461eba73e
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diff --git a/tests/sprites/point2frames.aseprite b/tests/sprites/point2frames.aseprite
new file mode 100644
index 000000000..1e97da0fb
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diff --git a/tests/sprites/point4frames.aseprite b/tests/sprites/point4frames.aseprite
new file mode 100644
index 000000000..a888f1734
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diff --git a/tests/sprites/tags3.aseprite b/tests/sprites/tags3.aseprite
new file mode 100644
index 000000000..dd9368965
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diff --git a/tests/third_party/json b/tests/third_party/json
new file mode 160000
index 000000000..dbf4b2dd2
--- /dev/null
+++ b/tests/third_party/json
@@ -0,0 +1 @@
+Subproject commit dbf4b2dd2eb7c23be2773c89eb059dadd6436f94