Add more test coverage to image handling (#30078)

packages/flutter/test/painting/image_provider_test.dart

@@ -86,4 +86,32 @@ void main() {
     });
     expect(await caughtError.future, true);
   });
+
+  test('ImageProvider.resolve sync errors will be caught', () async {
+    final ImageProvider imageProvider = LoadErrorImageProvider();
+    final Completer<bool> caughtError = Completer<bool>();
+    FlutterError.onError = (FlutterErrorDetails details) {
+      caughtError.complete(false);
+    };
+    final ImageStream result = imageProvider.resolve(ImageConfiguration.empty);
+    result.addListener((ImageInfo info, bool syncCall) {
+    }, onError: (dynamic error, StackTrace stackTrace) {
+      caughtError.complete(true);
+    });
+    expect(await caughtError.future, true);
+  });
+
+   test('ImageProvider.resolve errors in the completer will be caught', () async {
+    final ImageProvider imageProvider = LoadErrorCompleterImageProvider();
+    final Completer<bool> caughtError = Completer<bool>();
+    FlutterError.onError = (FlutterErrorDetails details) {
+      caughtError.complete(false);
+    };
+    final ImageStream result = imageProvider.resolve(ImageConfiguration.empty);
+    result.addListener((ImageInfo info, bool syncCall) {
+    }, onError: (dynamic error, StackTrace stackTrace) {
+      caughtError.complete(true);
+    });
+    expect(await caughtError.future, true);
+  });
 }

packages/flutter/test/painting/mocks_for_image_cache.dart

@@ -106,4 +106,28 @@ class ObtainKeyErrorImageProvider extends ImageProvider<ObtainKeyErrorImageProvi
   }
 }
 
+class LoadErrorImageProvider extends ImageProvider<LoadErrorImageProvider> {
+  @override
+  ImageStreamCompleter load(LoadErrorImageProvider key) {
+    throw Error();
+  }
+
+   @override
+  Future<LoadErrorImageProvider> obtainKey(ImageConfiguration configuration) {
+    return SynchronousFuture<LoadErrorImageProvider>(this);
+  }
+}
+
+ class LoadErrorCompleterImageProvider extends ImageProvider<LoadErrorCompleterImageProvider> {
+  @override
+  ImageStreamCompleter load(LoadErrorCompleterImageProvider key) {
+    return OneFrameImageStreamCompleter(SynchronousFuture<ImageInfo>(null).then((_) => throw Error()));
+  }
+
+   @override
+  Future<LoadErrorCompleterImageProvider> obtainKey(ImageConfiguration configuration) {
+    return SynchronousFuture<LoadErrorCompleterImageProvider>(this);
+  }
+}
+
 class TestImageStreamCompleter extends ImageStreamCompleter {}