Add color_scales_tests

src/doc/color_scales_tests.cpp

@@ -0,0 +1,46 @@
+// Aseprite Document Library
+// Copyright (c) 2022  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gtest/gtest.h>
+
+#include "doc/color_scales.h"
+
+#include <cmath>
+#include <cstdlib>
+
+using namespace doc;
+
+TEST(Scale, MatchValues)
+{
+  for (int x=1; x<=8; ++x) {
+    switch (x) {
+      case 3:
+        for (int v=0; v<8; ++v)
+          EXPECT_EQ(scale_3bits_to_8bits(v), scale_xxbits_to_8bits(3, v));
+        break;
+      case 5:
+        for (int v=0; v<32; ++v)
+          EXPECT_EQ(scale_5bits_to_8bits(v), scale_xxbits_to_8bits(5, v));
+        break;
+      case 6:
+        for (int v=0; v<64; ++v)
+          EXPECT_EQ(scale_6bits_to_8bits(v), scale_xxbits_to_8bits(6, v));
+        break;
+    }
+    for (int v=0; v<(1<<x); ++v)
+      EXPECT_LE(std::abs((255 * v / ((1<<x)-1)) - scale_xxbits_to_8bits(x, v)), 1);
+  }
+}
+
+int main(int argc, char** argv)
+{
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}