anchor.diff:          within<Color>(distance: 8, from: const Color(0xff00ff00)));
     });
   
  -  test('PaletteGenerator works as expected on a real image', () async {
  -    final ImageProvider image = await loadImage('landscape.png');
  +  testWidgets('PaletteGenerator works as expected on a real image',
  +      (WidgetTester tester) async {
  +    final ImageProvider image = testImages['landscape'];
       final PaletteGenerator palette =
           await PaletteGenerator.fromImageProvider(image);
       final List<PaletteColor> expectedSwatches = <PaletteColor>[
  
positive.code: 
  import 'dart:async';
  import 'dart:io';
  
  import 'package:flutter_test/flutter_test.dart';
  import 'package:flutter/material.dart';
  import 'package:path/path.dart' as path;
  import 'package:palette_generator/palette_generator.dart';
  
  Future<ImageProvider> loadImage(String name) async {
    File imagePath = new File(path.joinAll(<String>['assets', name]));
    if (path.split(Directory.current.absolute.path).last != 'test') {
      imagePath = new File(path.join('test', imagePath.path));
    }
    return new FileImage(imagePath);
  }
  
  void main() {
    test('PaletteGenerator works on 1-pixel wide blue image', () async {
      final ImageProvider image = await loadImage('tall_blue.png');
      final PaletteGenerator palette =
          await PaletteGenerator.fromImageProvider(image);
      expect(palette.paletteColors.length, equals(1));
  
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
  