Text: don't reuse the same pixel values in a test.

Could make bugs harder to discover this way.

src/Magnum/Text/Test/GlyphCacheGLTest.cpp

@@ -243,8 +243,8 @@ void GlyphCacheGLTest::constructMove() {
 const UnsignedByte InputData[]{
     0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
     0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
-    0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+    0x00, 0xff, 0x11, 0xee, 0x22, 0xdd, 0x33, 0xcc,
-    0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
+    0x44, 0xbb, 0x55, 0xaa, 0x66, 0x99, 0x77, 0x88
 };
 
 const UnsignedByte ExpectedData[]{
@@ -254,8 +254,8 @@ const UnsignedByte ExpectedData[]{
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
     0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
     0, 0, 0, 0, 0, 0, 0, 0, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
-    0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+    0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0xff, 0x11, 0xee, 0x22, 0xdd, 0x33, 0xcc,
-    0, 0, 0, 0, 0, 0, 0, 0, 0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
+    0, 0, 0, 0, 0, 0, 0, 0, 0x44, 0xbb, 0x55, 0xaa, 0x66, 0x99, 0x77, 0x88
 };
 
 void GlyphCacheGLTest::setImage() {
@@ -280,14 +280,14 @@ void GlyphCacheGLTest::setImage() {
     cache.flushImage(Range2Di::fromSize({8, 4}, {8, 4}));
     MAGNUM_VERIFY_NO_GL_ERROR();
 
-    MutableImageView3D actual3 = cache.image();
+    ImageView3D actual = cache.image();
-    /** @todo ugh have slicing on images directly already */
-    MutableImageView2D actual{actual3.format(), actual3.size().xy(), actual3.data()};
     MAGNUM_VERIFY_NO_GL_ERROR();
 
     /* The CPU-side image is zero-initialized, what was set above in the
        texture isn't present there */
-    CORRADE_COMPARE_AS(actual,
+    /** @todo ugh have slicing on images directly already, and 3D image
+        comparison */
+    CORRADE_COMPARE_AS((ImageView2D{actual.format(), actual.size().xy(), actual.data()}),
         (ImageView2D{PixelFormat::R8Unorm, {16, 8}, ExpectedData}),
         DebugTools::CompareImage);
 
@@ -318,9 +318,9 @@ void GlyphCacheGLTest::setImage() {
         0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0,
             0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
         0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0,
-            0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
+            0x00, 0xff, 0x11, 0xee, 0x22, 0xdd, 0x33, 0xcc,
         0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0xcd, 0,
-            0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
+            0x44, 0xbb, 0x55, 0xaa, 0x66, 0x99, 0x77, 0x88
     };
     CORRADE_COMPARE_AS(image,
         (ImageView2D{PixelFormat::R8Unorm, {16, 8}, expectedTextureData}),