[null-safety] remove mockito from network tests (#64284)

More work towards removal of mockito to facilitate strong null safety tests.

#62886

packages/flutter/test/painting/image_provider_network_image_test.dart

@@ -13,8 +13,8 @@ import 'dart:ui' show Codec, FrameInfo;
 import 'package:flutter/foundation.dart';
 import 'package:flutter/painting.dart';
 import 'package:flutter_test/flutter_test.dart';
-import 'package:mockito/mockito.dart';
 
+import '../flutter_test_alternative.dart' show Fake;
 import '../rendering/rendering_tester.dart';
 import 'image_data.dart';
 
@@ -25,10 +25,10 @@ void main() {
     return PaintingBinding.instance.instantiateImageCodec(bytes, cacheWidth: cacheWidth, cacheHeight: cacheHeight, allowUpscaling: allowUpscaling);
   };
 
-  _MockHttpClient httpClient;
+  _FakeHttpClient httpClient;
 
   setUp(() {
-    httpClient = _MockHttpClient();
+    httpClient = _FakeHttpClient();
     debugNetworkImageHttpClientProvider = () => httpClient;
   });
 
@@ -42,11 +42,7 @@ void main() {
     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);
+    httpClient.request.response.statusCode = errorStatusCode;
 
     final Completer<dynamic> caughtError = Completer<dynamic>();
 
@@ -84,7 +80,7 @@ void main() {
   });
 
   test('Uses the HttpClient provided by debugNetworkImageHttpClientProvider if set', () async {
-    when(httpClient.getUrl(any)).thenThrow('client1');
+    httpClient.thrownError = 'client1';
     final List<dynamic> capturedErrors = <dynamic>[];
 
     Future<void> loadNetworkImage() async {
@@ -101,15 +97,15 @@ void main() {
 
     await loadNetworkImage();
     expect(capturedErrors, <dynamic>['client1']);
-    final _MockHttpClient client2 = _MockHttpClient();
-    when(client2.getUrl(any)).thenThrow('client2');
+    final _FakeHttpClient client2 = _FakeHttpClient();
+    client2.thrownError = 'client2';
     debugNetworkImageHttpClientProvider = () => client2;
     await loadNetworkImage();
     expect(capturedErrors, <dynamic>['client1', 'client2']);
   }, skip: isBrowser); // Browser implementation does not use HTTP client but an <img> tag.
 
   test('Propagates http client errors during resolve()', () async {
-    when(httpClient.getUrl(any)).thenThrow(Error());
+    httpClient.thrownError = Error();
     bool uncaught = false;
 
     final FlutterExceptionHandler oldError = FlutterError.onError;
@@ -141,30 +137,11 @@ void main() {
         Uint8List.fromList(kTransparentImage.skip(offset).take(chunkSize).toList()),
     ];
     final Completer<void> imageAvailable = Completer<void>();
-    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(HttpStatus.ok);
-    when(response.contentLength).thenReturn(kTransparentImage.length);
-    when(response.listen(
-      any,
-      onDone: anyNamed('onDone'),
-      onError: anyNamed('onError'),
-      cancelOnError: anyNamed('cancelOnError'),
-    )).thenAnswer((Invocation invocation) {
-      final void Function(List<int>) onData = invocation.positionalArguments[0] as void Function(List<int>);
-      final void Function(Object) onError = invocation.namedArguments[#onError] as void Function(Object);
-      final VoidCallback onDone = invocation.namedArguments[#onDone] as VoidCallback;
-      final bool cancelOnError = invocation.namedArguments[#cancelOnError] as bool;
-
-      return Stream<Uint8List>.fromIterable(chunks).listen(
-        onData,
-        onDone: onDone,
-        onError: onError,
-        cancelOnError: cancelOnError,
-      );
-    });
+
+    httpClient.request.response
+      ..statusCode = HttpStatus.ok
+      ..contentLength = kTransparentImage.length
+      ..content = chunks;
 
     final ImageProvider imageProvider = NetworkImage(nonconst('foo'));
     final ImageStream result = imageProvider.resolve(ImageConfiguration.empty);
@@ -189,11 +166,10 @@ void main() {
   }, skip: isBrowser); // Browser loads images through <img> not Http.
 
   test('NetworkImage is evicted from cache on SocketException', () async {
-    final _MockHttpClient mockHttpClient = _MockHttpClient();
-    when(mockHttpClient.getUrl(any)).thenAnswer((_) => throw const SocketException('test exception'));
+    final _FakeHttpClient mockHttpClient = _FakeHttpClient();
+    mockHttpClient.thrownError = const SocketException('test exception');
     debugNetworkImageHttpClientProvider = () => mockHttpClient;
 
-
     final ImageProvider imageProvider = NetworkImage(nonconst('testing.url'));
     expect(imageCache.pendingImageCount, 0);
     expect(imageCache.statusForKey(imageProvider).untracked, true);
@@ -232,30 +208,10 @@ void main() {
       for (int offset = 0; offset < kTransparentImage.length; offset += chunkSize)
         Uint8List.fromList(kTransparentImage.skip(offset).take(chunkSize).toList()),
     ];
-    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(HttpStatus.ok);
-    when(response.contentLength).thenReturn(kTransparentImage.length);
-    when(response.listen(
-      any,
-      onDone: anyNamed('onDone'),
-      onError: anyNamed('onError'),
-      cancelOnError: anyNamed('cancelOnError'),
-    )).thenAnswer((Invocation invocation) {
-      final void Function(List<int>) onData = invocation.positionalArguments[0] as void Function(List<int>);
-      final void Function(Object) onError = invocation.namedArguments[#onError] as void Function(Object);
-      final VoidCallback onDone = invocation.namedArguments[#onDone] as VoidCallback;
-      final bool cancelOnError = invocation.namedArguments[#cancelOnError] as bool;
-
-      return Stream<Uint8List>.fromIterable(chunks).listen(
-        onData,
-        onDone: onDone,
-        onError: onError,
-        cancelOnError: cancelOnError,
-      );
-    });
+    httpClient.request.response
+      ..statusCode = HttpStatus.ok
+      ..contentLength = kTransparentImage.length
+      ..content = chunks;
 
     const NetworkImage provider = NetworkImage(url);
 
@@ -263,12 +219,51 @@ void main() {
 
     expect(completer.debugLabel, url);
   });
+}
+
+class _FakeHttpClient extends Fake implements HttpClient {
+  final _FakeHttpClientRequest request = _FakeHttpClientRequest();
+  dynamic thrownError;
+
+  @override
+  Future<HttpClientRequest> getUrl(Uri url) async {
+    if (thrownError != null) {
+      throw thrownError;
+    }
+    return request;
+  }
+}
+class _FakeHttpClientRequest extends Fake implements HttpClientRequest {
+  final _FakeHttpClientResponse response = _FakeHttpClientResponse();
 
+  @override
+  Future<HttpClientResponse> close() async {
+    return response;
+  }
 }
 
-class _MockHttpClient extends Mock implements HttpClient {}
-class _MockHttpClientRequest extends Mock implements HttpClientRequest {}
-class _MockHttpClientResponse extends Mock implements HttpClientResponse {}
+class _FakeHttpClientResponse extends Fake implements HttpClientResponse {
+  @override
+  int statusCode = HttpStatus.ok;
+
+  @override
+  int contentLength = 0;
+
+  @override
+  HttpClientResponseCompressionState get compressionState => HttpClientResponseCompressionState.notCompressed;
+
+  List<List<int>> content;
+
+  @override
+  StreamSubscription<List<int>> listen(void Function(List<int> event) onData, {Function onError, void Function() onDone, bool cancelOnError}) {
+    return Stream<List<int>>.fromIterable(content).listen(
+      onData,
+      onDone: onDone,
+      onError: onError,
+      cancelOnError: cancelOnError,
+    );
+  }
+}
 
 class FakeCodec implements Codec {
   @override