Reland: Skia gold driver test (#50160)

dev/devicelab/bin/tasks/flutter_driver_screenshot_test_fuchsia.dart

@@ -10,5 +10,5 @@ import 'package:flutter_devicelab/tasks/integration_tests.dart';
 
 Future<void> main() async {
   deviceOperatingSystem = DeviceOperatingSystem.fuchsia;
-  await task(createFlutterDriverScreenshotTest());
+  await task(createFlutterDriverScreenshotTest(useFlutterGold: true));
 }

dev/devicelab/lib/tasks/integration_tests.dart

@@ -107,15 +107,22 @@ TaskFunction createAndroidSplashScreenKitchenSinkTest() {
   );
 }
 
-TaskFunction createFlutterDriverScreenshotTest() {
+/// Executes a driver test that takes a screenshot and compares it against a golden image.
+/// If [useFlutterGold] is true, the golden image is served by Flutter Gold
+/// (https://flutter-gold.skia.org/), otherwise the golden image is read from the disk.
+TaskFunction createFlutterDriverScreenshotTest({
+  bool useFlutterGold = false,
+}) {
   return DriverTest(
     '${flutterDirectory.path}/dev/integration_tests/flutter_driver_screenshot_test',
     'lib/main.dart',
+    extraOptions: useFlutterGold ? const <String>[
+      '--driver', 'test_driver/flutter_gold_main_test.dart'
+    ] : const <String>[]
   );
 }
 
 class DriverTest {
-
   DriverTest(
     this.testDirectory,
     this.testTarget, {

dev/integration_tests/flutter_driver_screenshot_test/README.md

@@ -4,7 +4,12 @@ This tests contains an app with a main page and sub pages.
 The main page contains a list of buttons; each button leads to a designated sub page when tapped on.
 Each sub page should displays some simple UIs to screenshot tested.
 
-The flutter driver test runs the app and opens each page to take a screenshot. Then it compares the screenshot against a golden image stored in `test_driver/goldens/<some_test_page_name>/<device_model>.png`.
+The flutter driver test runs the app and opens each page to take a screenshot.
+
+Use `test_driver/flutter_gold_main_test.dart` to test against golden files stored on Flutter Gold.
+Otherwise, use `main_test.dart` to test against golden files stored on `test_driver/goldens/<some_test_page_name>/<device_model>.png`.
+
+Note that new binaries can't be checked in the Flutter repo, so use [Flutter Gold](https://github.com/flutter/flutter/wiki/Writing-a-golden-file-test-for-package:flutter) instead.
 
 # Add a new page to test
 
@@ -16,6 +21,7 @@ The flutter driver test runs the app and opens each page to take a screenshot. T
 
 An example of a `Page` subclass can be found in `lib/image_page.dart`
 
-# Experiments
+# Environments
 
-The test currently only runs on device lab ["mac/ios"] which runs the app on iPhone 6s.
+* Device Lab which runs the app on iPhone 6s.
\ No newline at end of file
+* LUCI which runs the app on a Fuchsia NUC device.

dev/integration_tests/flutter_driver_screenshot_test/test_driver/flutter_gold_main_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'package:flutter_driver/flutter_driver.dart';
+import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
+import 'package:flutter_test/src/buffer_matcher.dart';
+
+Future<void> main() async {
+  FlutterDriver driver;
+  String deviceModel;
+
+  setUpAll(() async {
+    driver = await FlutterDriver.connect();
+    deviceModel = await driver.requestData('device_model');
+  });
+
+  tearDownAll(() => driver.close());
+
+  test('A page with an image screenshot', () async {
+    final SerializableFinder imagePageListTile =
+        find.byValueKey('image_page');
+    await driver.waitFor(imagePageListTile);
+    await driver.tap(imagePageListTile);
+    await driver.waitFor(find.byValueKey('red_square_image'));
+    await driver.waitUntilNoTransientCallbacks();
+
+    // TODO(egarciad): This is currently a no-op on LUCI.
+    // https://github.com/flutter/flutter/issues/49837
+    await expectLater(
+      driver.screenshot(),
+      bufferMatchesGoldenFile('red_square_driver_screenshot__$deviceModel.png'),
+    );
+
+    await driver.tap(find.byTooltip('Back'));
+  });
+}

packages/flutter_test/lib/src/_goldens_io.dart

@@ -8,7 +8,6 @@ import 'dart:math' as math;
 import 'dart:typed_data';
 import 'dart:ui';
 
-import 'package:flutter/widgets.dart' show Element;
 import 'package:image/image.dart';
 import 'package:path/path.dart' as path;
 // ignore: deprecated_member_use
@@ -246,12 +245,12 @@ ComparisonResult compareLists(List<int> test, List<int> master) {
 /// An unsupported [WebGoldenComparator] that exists for API compatibility.
 class DefaultWebGoldenComparator extends WebGoldenComparator {
   @override
-  Future<bool> compare(Element element, Size size, Uri golden) {
+  Future<bool> compare(double width, double height, Uri golden) {
     throw UnsupportedError('DefaultWebGoldenComparator is only supported on the web.');
   }
 
   @override
-  Future<void> update(Uri golden, Element element, Size size) {
+  Future<void> update(double width, double height, Uri golden) {
     throw UnsupportedError('DefaultWebGoldenComparator is only supported on the web.');
   }
 }

packages/flutter_test/lib/src/_goldens_web.dart

@@ -5,10 +5,7 @@
 import 'dart:convert';
 import 'dart:html' as html;
 import 'dart:typed_data';
-import 'dart:ui';
 
-import 'package:flutter/rendering.dart';
-import 'package:flutter/widgets.dart';
 // ignore: deprecated_member_use
 import 'package:test_api/test_api.dart' as test_package show TestFailure;
 
@@ -60,17 +57,16 @@ class DefaultWebGoldenComparator extends WebGoldenComparator {
   Uri testUri;
 
   @override
-  Future<bool> compare(Element element, Size size, Uri golden) async {
+  Future<bool> compare(double width, double height, Uri golden) async {
     final String key = golden.toString();
-
     final html.HttpRequest request = await html.HttpRequest.request(
       'flutter_goldens',
       method: 'POST',
       sendData: json.encode(<String, Object>{
         'testUri': testUri.toString(),
         'key': key.toString(),
-        'width': size.width.round(),
-        'height': size.height.round(),
+        'width': width.round(),
+        'height': height.round(),
       }),
     );
     final String response = request.response as String;
@@ -82,8 +78,8 @@ class DefaultWebGoldenComparator extends WebGoldenComparator {
   }
 
   @override
-  Future<void> update(Uri golden, Element element, Size size) async {
+  Future<void> update(double width, double height, Uri golden) async {
     // Update is handled on the server side, just use the same logic here
-    await compare(element, size, golden);
+    await compare(width, height, golden);
   }
 }

packages/flutter_test/lib/src/_matchers_web.dart

@@ -60,11 +60,11 @@ class MatchesGoldenFile extends AsyncMatcher {
     _renderElement(binding.window, renderObject);
     final String result = await binding.runAsync<String>(() async {
       if (autoUpdateGoldenFiles) {
-        await webGoldenComparator.update(key, element, size);
+        await webGoldenComparator.update(size.width, size.height, key);
         return null;
       }
       try {
-        final bool success = await webGoldenComparator.compare(element, size, key);
+        final bool success = await webGoldenComparator.compare(size.width, size.height, key);
         return success ? null : 'does not match';
       } on TestFailure catch (ex) {
         return ex.message;

packages/flutter_test/lib/src/buffer_matcher.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:typed_data';
+
+import 'package:test_api/src/frontend/async_matcher.dart'; // ignore: implementation_imports
+// ignore: deprecated_member_use
+import 'package:test_api/test_api.dart' show Description, TestFailure;
+
+import 'goldens.dart';
+
+/// Matcher created by [bufferMatchesGoldenFile].
+class _BufferGoldenMatcher extends AsyncMatcher {
+  /// Creates an instance of [BufferGoldenMatcher]. Called by [bufferMatchesGoldenFile].
+  const _BufferGoldenMatcher(this.key, this.version);
+
+  /// The [key] to the golden image.
+  final Uri key;
+
+  /// The [version] of the golden image.
+  final int version;
+
+  @override
+  Future<String> matchAsync(dynamic item) async {
+    Uint8List buffer;
+    if (item is List<int>) {
+      buffer = Uint8List.fromList(item);
+    } else if (item is Future<List<int>>) {
+      buffer = Uint8List.fromList(await item);
+    } else {
+      throw 'Expected `List<int>` or `Future<List<int>>`, instead found: ${item.runtimeType}';
+    }
+    final Uri testNameUri = goldenFileComparator.getTestUri(key, version);
+    if (autoUpdateGoldenFiles) {
+      await goldenFileComparator.update(testNameUri, buffer);
+      return null;
+    }
+    try {
+      final bool success = await goldenFileComparator.compare(buffer, testNameUri);
+      return success ? null : 'does not match';
+    } on TestFailure catch (ex) {
+      return ex.message;
+    }
+  }
+
+  @override
+  Description describe(Description description) {
+    final Uri testNameUri = goldenFileComparator.getTestUri(key, version);
+    return description.add('Byte buffer matches golden image "$testNameUri"');
+  }
+}
+
+/// Asserts that a [Future<List<int>>], or [List<int] matches the
+/// golden image file identified by [key], with an optional [version] number.
+///
+/// The [key] is the [String] representation of a URL.
+///
+/// The [version] is a number that can be used to differentiate historical
+/// golden files. This parameter is optional.
+///
+/// {@tool snippet}
+/// Sample invocations of [matchesGoldenFile].
+///
+/// ```dart
+/// await expectLater(
+///   const <int>[],
+///   bufferMatchesGoldenFile('sample.png'),
+/// );
+/// ```
+/// {@end-tool}
+AsyncMatcher bufferMatchesGoldenFile(String key, {int version}) {
+   return _BufferGoldenMatcher(Uri.parse(key), version);
+}

packages/flutter_test/lib/src/goldens.dart

@@ -5,8 +5,7 @@
 import 'dart:async';
 import 'dart:typed_data';
 
-import 'package:flutter/foundation.dart';
-import 'package:flutter/widgets.dart';
+import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
 import '_goldens_io.dart' if (dart.library.html) '_goldens_web.dart' as _goldens;
 
@@ -158,7 +157,7 @@ set goldenFileComparator(GoldenFileComparator value) {
 ///  * [matchesGoldenFile], the function from [flutter_test] that invokes the
 ///    comparator.
 abstract class WebGoldenComparator {
-  /// Compares the rendered pixels of [element] of size [size] that is being
+  /// Compares the rendered pixels of size [width]x[height] that is being
   /// rendered on the top left of the screen against the golden file identified
   /// by [golden].
   ///
@@ -174,10 +173,10 @@ abstract class WebGoldenComparator {
   /// is left up to the implementation class. For instance, some implementations
   /// may load files from the local file system, whereas others may load files
   /// over the network or from a remote repository.
-  Future<bool> compare(Element element, Size size, Uri golden);
+  Future<bool> compare(double width, double height, Uri golden);
 
   /// Updates the golden file identified by [golden] with rendered pixels of
-  /// [element].
+  /// [width]x[height].
   ///
   /// This will be invoked in lieu of [compare] when [autoUpdateGoldenFiles]
   /// is `true` (which gets set automatically by the test framework when the
@@ -185,7 +184,7 @@ abstract class WebGoldenComparator {
   ///
   /// The method by which [golden] is located and by which its bytes are written
   /// is left up to the implementation class.
-  Future<void> update(Uri golden, Element element, Size size);
+  Future<void> update(double width, double height, Uri golden);
 
   /// Returns a new golden file [Uri] to incorporate any [version] number with
   /// the [key].
@@ -280,7 +279,7 @@ class TrivialComparator implements GoldenFileComparator {
 
   @override
   Future<bool> compare(Uint8List imageBytes, Uri golden) {
-    debugPrint('Golden file comparison requested for "$golden"; skipping...');
+    print('Golden file comparison requested for "$golden"; skipping...');
     return Future<bool>.value(true);
   }
 
@@ -299,13 +298,13 @@ class _TrivialWebGoldenComparator implements WebGoldenComparator {
   const _TrivialWebGoldenComparator._();
 
   @override
-  Future<bool> compare(Element element, Size size, Uri golden) {
-    debugPrint('Golden comparison requested for "$golden"; skipping...');
+  Future<bool> compare(double width, double height, Uri golden) {
+    print('Golden comparison requested for "$golden"; skipping...');
     return Future<bool>.value(true);
   }
 
   @override
-  Future<void> update(Uri golden, Element element, Size size) {
+  Future<void> update(double width, double height, Uri golden) {
     throw StateError('webGoldenComparator has not been initialized');
   }