travis/linux: Install dependencies and run tests with an X11 server

.travis.yml

@@ -7,26 +7,37 @@ matrix:
       env:
         - ENABLE_UI=ON
     - os: linux
+      addons:
+        apt:
+          packages:
+            - libpixman-1-dev libfreetype6-dev libharfbuzz-dev libx11-dev libxcursor-dev
       env:
         - ENABLE_UI=OFF
+        - XVFB=xvfb-run
     - os: linux
+      addons:
+        apt:
+          packages:
+            - libpixman-1-dev libfreetype6-dev libharfbuzz-dev libx11-dev libxcursor-dev
       env:
         - ENABLE_UI=ON
+        - XVFB=xvfb-run
     - os: linux
       addons:
         apt:
           sources:
             - ubuntu-toolchain-r-test
           packages:
-            - g++-7
+            - g++-7 libpixman-1-dev libfreetype6-dev libharfbuzz-dev libx11-dev libxcursor-dev
       env:
         - MATRIX_EVAL="CC=gcc-7 && CXX=g++-7"
         - ENABLE_UI=ON
+        - XVFB=xvfb-run
 
 before_script:
   - mkdir build
   - cd build
-  - cmake .. -DENABLE_TESTS=ON -DENABLE_UI=$ENABLE_UI
+  - $XVFB cmake .. -DENABLE_TESTS=ON -DENABLE_UI=$ENABLE_UI
 
 script:
   - make
@@ -36,6 +47,6 @@ script:
         export ASEPRITE=$PWD/bin/aseprite
         git clone https://github.com/aseprite/tests.git
         cd tests
-        bash run-tests.sh
+        $XVFB bash run-tests.sh
       fi
     fi