anchor.diff:      return PaintingBinding.instance.instantiateImageCodec(bytes, cacheWidth: cacheWidth, cacheHeight: cacheHeight, allowUpscaling: allowUpscaling);
     };
   
  -  _MockHttpClient httpClient;
  +  _FakeHttpClient httpClient;
   
     setUp(() {
  -    httpClient = _MockHttpClient();
  +    httpClient = _FakeHttpClient();
       debugNetworkImageHttpClientProvider = () => httpClient;
     });
   
  
positive.code:     final int errorStatusCode = HttpStatus.notFound;
      const String requestUrl = 'foo-url';
  
      final _MockHttpClientRequest request = _MockHttpClientRequest();
      final _MockHttpClientResponse response = _MockHttpClientResponse();
      when(httpClient.getUrl(any)).thenAnswer((_) => Future<HttpClientRequest>.value(request));
      when(request.close()).thenAnswer((_) => Future<HttpClientResponse>.value(response));
      when(response.statusCode).thenReturn(errorStatusCode);
  
      final Completer<dynamic> caughtError = Completer<dynamic>();
  
  
negative.code: import 'package:flutter/foundation.dart';
  import 'package:flutter/painting.dart';
  import 'package:flutter_test/flutter_test.dart';
  
  import '../flutter_test_alternative.dart' show Fake;
  import '../rendering/rendering_tester.dart';
  import 'image_data.dart';
  
  