anchor.diff:          within<Color>(distance: 8, from: const Color(0xff0000ff)));
     });
   
  -  test('PaletteGenerator works on 1-pixel high red image', () async {
  -    final ImageProvider image = await loadImage('wide_red.png');
  +  testWidgets('PaletteGenerator works on 1-pixel high red image',
  +      (WidgetTester tester) async {
  +    final ImageProvider image = testImages['wide_red'];
       final PaletteGenerator palette =
           await PaletteGenerator.fromImageProvider(image);
       expect(palette.paletteColors.length, equals(1));
  
positive.code:         within<Color>(distance: 8, from: const Color(0xda000000)));
    });
  
    test('PaletteGenerator works with regions', () async {
      final ImageProvider image = await loadImage('dominant.png');
      Rect region = new Rect.fromLTRB(0.0, 0.0, 100.0, 100.0);
      PaletteGenerator palette =
          await PaletteGenerator.fromImageProvider(image, region: region);
  
negative.code:     expect(palette.paletteColors.length, equals(15));
    });
  
    testWidgets('PaletteGenerator Filters work', (WidgetTester tester) async {
      final ImageProvider image = testImages['landscape'];
      // First, test that supplying the default filter is the same as not supplying one.
      List<PaletteFilter> filters = <PaletteFilter>[
        avoidRedBlackWhitePaletteFilter
  