Fix memory leak in _MatchesReferenceImage (#135150)

packages/flutter_test/lib/src/matchers.dart

@@ -576,7 +576,9 @@ AsyncMatcher matchesGoldenFile(Object key, {int? version}) {
 ///   final ui.Canvas pictureCanvas = ui.Canvas(recorder);
 ///   pictureCanvas.drawCircle(Offset.zero, 20.0, paint);
 ///   final ui.Picture picture = recorder.endRecording();
+///   addTearDown(picture.dispose);
 ///   ui.Image referenceImage = await picture.toImage(50, 50);
+///   addTearDown(referenceImage.dispose);
 ///
 ///   await expectLater(find.text('Save'), matchesReferenceImage(referenceImage));
 ///   await expectLater(image, matchesReferenceImage(referenceImage));
@@ -2139,10 +2141,13 @@ class _MatchesReferenceImage extends AsyncMatcher {
   @override
   Future<String?> matchAsync(dynamic item) async {
     Future<ui.Image> imageFuture;
+    final bool disposeImage; // set to true if the matcher created and owns the image and must therefore dispose it.
     if (item is Future<ui.Image>) {
       imageFuture = item;
+      disposeImage = false;
     } else if (item is ui.Image) {
       imageFuture = Future<ui.Image>.value(item);
+      disposeImage = false;
     } else {
       final Finder finder = item as Finder;
       final Iterable<Element> elements = finder.evaluate();
@@ -2152,30 +2157,37 @@ class _MatchesReferenceImage extends AsyncMatcher {
         return 'matched too many widgets';
       }
       imageFuture = captureImage(elements.single);
+      disposeImage = true;
     }
 
     final TestWidgetsFlutterBinding binding = TestWidgetsFlutterBinding.instance;
     return binding.runAsync<String?>(() async {
       final ui.Image image = await imageFuture;
-      final ByteData? bytes = await image.toByteData();
-      if (bytes == null) {
-        return 'could not be encoded.';
-      }
+      try {
+        final ByteData? bytes = await image.toByteData();
+        if (bytes == null) {
+          return 'could not be encoded.';
+        }
 
-      final ByteData? referenceBytes = await referenceImage.toByteData();
-      if (referenceBytes == null) {
-        return 'could not have its reference image encoded.';
-      }
+        final ByteData? referenceBytes = await referenceImage.toByteData();
+        if (referenceBytes == null) {
+          return 'could not have its reference image encoded.';
+        }
 
-      if (referenceImage.height != image.height || referenceImage.width != image.width) {
-        return 'does not match as width or height do not match. $image != $referenceImage';
-      }
+        if (referenceImage.height != image.height || referenceImage.width != image.width) {
+          return 'does not match as width or height do not match. $image != $referenceImage';
+        }
 
-      final int countDifferentPixels = _countDifferentPixels(
-        Uint8List.view(bytes.buffer),
-        Uint8List.view(referenceBytes.buffer),
-      );
-      return countDifferentPixels == 0 ? null : 'does not match on $countDifferentPixels pixels';
+        final int countDifferentPixels = _countDifferentPixels(
+          Uint8List.view(bytes.buffer),
+          Uint8List.view(referenceBytes.buffer),
+        );
+        return countDifferentPixels == 0 ? null : 'does not match on $countDifferentPixels pixels';
+      } finally {
+        if (disposeImage) {
+          image.dispose();
+        }
+      }
     });
   }
 

packages/flutter_test/pubspec.yaml

@@ -44,5 +44,43 @@ dependencies:
 
 dev_dependencies:
   file: 6.1.4
+  # Used to detect memory leaks.
+  leak_tracker_flutter_testing: 1.0.5
 
-# PUBSPEC CHECKSUM: 9e5d
+  _fe_analyzer_shared: 64.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  analyzer: 6.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  args: 2.4.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  convert: 3.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  coverage: 1.6.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  crypto: 3.0.3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  frontend_server_client: 3.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  glob: 2.1.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  http_multi_server: 3.2.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  http_parser: 4.0.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  intl: 0.18.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  io: 1.0.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  js: 0.6.7 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  leak_tracker: 9.0.7 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  leak_tracker_testing: 1.0.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  logging: 1.2.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  mime: 1.0.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  node_preamble: 2.0.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  package_config: 2.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  pool: 1.5.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  pub_semver: 2.1.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  shelf: 1.4.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  shelf_packages_handler: 3.0.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  shelf_static: 1.1.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  shelf_web_socket: 1.0.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  source_map_stack_trace: 2.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  source_maps: 0.10.12 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  test: 1.24.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  test_core: 0.5.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  typed_data: 1.3.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  vm_service: 11.10.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  watcher: 1.1.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  web_socket_channel: 2.4.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  webkit_inspection_protocol: 1.2.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  yaml: 3.1.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+
+# PUBSPEC CHECKSUM: aa8d

packages/flutter_test/test/reference_image_test.dart

@@ -4,9 +4,12 @@
 
 import 'dart:ui' as ui;
 
+import 'package:flutter/rendering.dart';
+import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
-Future<ui.Image> createTestImage(int width, int height, ui.Color color) {
+Future<ui.Image> createTestImage(int width, int height, ui.Color color) async {
   final ui.Paint paint = ui.Paint()
     ..style = ui.PaintingStyle.stroke
     ..strokeWidth = 1.0
@@ -15,7 +18,9 @@ Future<ui.Image> createTestImage(int width, int height, ui.Color color) {
   final ui.Canvas pictureCanvas = ui.Canvas(recorder);
   pictureCanvas.drawCircle(Offset.zero, 20.0, paint);
   final ui.Picture picture = recorder.endRecording();
-  return picture.toImage(width, height);
+  final ui.Image image = await picture.toImage(width, height);
+  picture.dispose();
+  return image;
 }
 
 void main() {
@@ -24,50 +29,121 @@ void main() {
   const ui.Color transparentRed = ui.Color.fromARGB(128, 255, 0, 0);
 
   group('succeeds', () {
-    testWidgets('when images have the same content', (WidgetTester tester) async {
-      await expectLater(
-        await createTestImage(100, 100, red),
-        matchesReferenceImage(await createTestImage(100, 100, red)),
-      );
-      await expectLater(
-        await createTestImage(100, 100, green),
-        matchesReferenceImage(await createTestImage(100, 100, green)),
-      );
+    testWidgetsWithLeakTracking('when images have the same content', (WidgetTester tester) async {
+      final ui.Image image1 = await createTestImage(100, 100, red);
+      addTearDown(image1.dispose);
+      final ui.Image referenceImage1 = await createTestImage(100, 100, red);
+      addTearDown(referenceImage1.dispose);
 
-      await expectLater(
-        await createTestImage(100, 100, transparentRed),
-        matchesReferenceImage(await createTestImage(100, 100, transparentRed)),
-      );
+      await expectLater(image1, matchesReferenceImage(referenceImage1));
+
+      final ui.Image image2 = await createTestImage(100, 100, green);
+      addTearDown(image2.dispose);
+      final ui.Image referenceImage2 = await createTestImage(100, 100, green);
+      addTearDown(referenceImage2.dispose);
+
+      await expectLater(image2, matchesReferenceImage(referenceImage2));
+
+      final ui.Image image3 = await createTestImage(100, 100, transparentRed);
+      addTearDown(image3.dispose);
+      final ui.Image referenceImage3 = await createTestImage(100, 100, transparentRed);
+      addTearDown(referenceImage3.dispose);
+
+      await expectLater(image3, matchesReferenceImage(referenceImage3));
     });
 
-    testWidgets('when images are identical', (WidgetTester tester) async {
+    testWidgetsWithLeakTracking('when images are identical', (WidgetTester tester) async {
       final ui.Image image = await createTestImage(100, 100, red);
+      addTearDown(image.dispose);
       await expectLater(image, matchesReferenceImage(image));
     });
+
+    testWidgetsWithLeakTracking('when widget looks the same', (WidgetTester tester) async {
+      addTearDown(tester.view.reset);
+      tester.view
+        ..physicalSize = const Size(10, 10)
+        ..devicePixelRatio = 1;
+
+      const ValueKey<String> repaintBoundaryKey = ValueKey<String>('boundary');
+
+      await tester.pumpWidget(
+        const RepaintBoundary(
+          key: repaintBoundaryKey,
+          child: ColoredBox(color: red),
+        ),
+      );
+
+      final ui.Image referenceImage = (tester.renderObject(find.byKey(repaintBoundaryKey)) as RenderRepaintBoundary).toImageSync();
+      addTearDown(referenceImage.dispose);
+
+      await expectLater(find.byKey(repaintBoundaryKey), matchesReferenceImage(referenceImage));
+    });
   });
 
   group('fails', () {
-    testWidgets('when image sizes do not match', (WidgetTester tester) async {
+    testWidgetsWithLeakTracking('when image sizes do not match', (WidgetTester tester) async {
       final ui.Image red50 = await createTestImage(50, 50, red);
+      addTearDown(red50.dispose);
       final ui.Image red100 = await createTestImage(100, 100, red);
+      addTearDown(red100.dispose);
+
       expect(
         await matchesReferenceImage(red50).matchAsync(red100),
         equals('does not match as width or height do not match. [100×100] != [50×50]'),
       );
     });
 
-    testWidgets('when image pixels do not match', (WidgetTester tester) async {
+    testWidgetsWithLeakTracking('when image pixels do not match', (WidgetTester tester) async {
       final ui.Image red100 = await createTestImage(100, 100, red);
+      addTearDown(red100.dispose);
       final ui.Image transparentRed100 = await createTestImage(100, 100, transparentRed);
+      addTearDown(transparentRed100.dispose);
+
       expect(
         await matchesReferenceImage(red100).matchAsync(transparentRed100),
         equals('does not match on 57 pixels'),
       );
+
       final ui.Image green100 = await createTestImage(100, 100, green);
+      addTearDown(green100.dispose);
+
       expect(
         await matchesReferenceImage(red100).matchAsync(green100),
         equals('does not match on 57 pixels'),
       );
     });
+
+    testWidgetsWithLeakTracking('when widget does not look the same', (WidgetTester tester) async {
+      addTearDown(tester.view.reset);
+      tester.view
+        ..physicalSize = const Size(10, 10)
+        ..devicePixelRatio = 1;
+
+      const ValueKey<String> repaintBoundaryKey = ValueKey<String>('boundary');
+
+      await tester.pumpWidget(
+        const RepaintBoundary(
+          key: repaintBoundaryKey,
+          child: ColoredBox(color: red),
+        ),
+      );
+
+      final ui.Image referenceImage = (tester.renderObject(find.byKey(repaintBoundaryKey)) as RenderRepaintBoundary).toImageSync();
+      addTearDown(referenceImage.dispose);
+
+      await tester.pumpWidget(
+        const RepaintBoundary(
+          key: repaintBoundaryKey,
+          child: ColoredBox(color: green),
+        ),
+      );
+
+      expect(
+        await matchesReferenceImage(referenceImage).matchAsync(
+          find.byKey(repaintBoundaryKey),
+        ),
+        equals('does not match on 100 pixels'),
+      );
+    });
   });
 }