add option for bulk-updating screenshots; update screenshots

lib/web_ui/dev/felt.dart

@@ -15,7 +15,7 @@ CommandRunner runner = CommandRunner<bool>(
   'Command-line utility for building and testing Flutter web engine.',
 )
   ..addCommand(LicensesCommand())
-  ..addCommand(TestsCommand())
+  ..addCommand(TestCommand())
   ..addCommand(BuildCommand());
 
 void main(List<String> args) async {

lib/web_ui/dev/goldens_lock.yaml

@@ -1,2 +1,2 @@
 repository: https://github.com/flutter/goldens.git
-revision: dd993a32c23c5c542f083134467e7cda09cac975
+revision: 17a42169bbf6739421fce8a0a1695eb3405375b6

lib/web_ui/dev/test_platform.dart

@@ -55,14 +55,16 @@ class BrowserPlatform extends PlatformPlugin {
   ///
   /// [root] is the root directory that the server should serve. It defaults to
   /// the working directory.
-  static Future<BrowserPlatform> start({String root}) async {
+  static Future<BrowserPlatform> start({String root, bool doUpdateScreenshotGoldens: false}) async {
     var server = shelf_io.IOServer(await HttpMultiServer.loopback(0));
     return BrowserPlatform._(
-        server,
-        Configuration.current,
-        p.fromUri(await Isolate.resolvePackageUri(
-            Uri.parse('package:test/src/runner/browser/static/favicon.ico'))),
-        root: root);
+      server,
+      Configuration.current,
+      p.fromUri(await Isolate.resolvePackageUri(
+          Uri.parse('package:test/src/runner/browser/static/favicon.ico'))),
+      root: root,
+      doUpdateScreenshotGoldens: doUpdateScreenshotGoldens,
+    );
   }
 
   /// The test runner configuration.
@@ -99,8 +101,11 @@ class BrowserPlatform extends PlatformPlugin {
   /// Whether [close] has been called.
   bool get _closed => _closeMemo.hasRun;
 
+  /// Whether to update screenshot golden files.
+  final bool doUpdateScreenshotGoldens;
+
   BrowserPlatform._(this._server, Configuration config, String faviconPath,
-      {String root})
+      {String root, this.doUpdateScreenshotGoldens})
       : _config = config,
         _root = root == null ? p.current : root,
         _http = config.pubServeUrl == null ? null : HttpClient() {
@@ -147,6 +152,10 @@ class BrowserPlatform extends PlatformPlugin {
   }
 
   Future<String> _diffScreenshot(String filename, bool write, [ Map<String, dynamic> region ]) async {
+    if (doUpdateScreenshotGoldens) {
+      write = true;
+    }
+
     String goldensDirectory;
     if (filename.startsWith('__local__')) {
       filename = filename.substring('__local__/'.length);
@@ -213,8 +222,14 @@ To automatically create this file call matchGoldenFile('$filename', write: true)
 
     if (write) {
       // Don't even bother with the comparison, just write and return
+      print('Updating screenshot golden: $file');
       file.writeAsBytesSync(encodePng(screenshot), flush: true);
-      return 'Golden file $filename was updated. You can remove "write: true" in the call to matchGoldenFile.';
+      if (doUpdateScreenshotGoldens) {
+        // Do not fail tests when bulk-updating screenshot goldens.
+        return 'OK';
+      } else {
+        return 'Golden file $filename was updated. You can remove "write: true" in the call to matchGoldenFile.';
+      }
     }
 
     ImageDiff diff = ImageDiff(golden: decodeNamedImage(file.readAsBytesSync(), filename), other: screenshot);

lib/web_ui/dev/test_runner.dart

@@ -19,8 +19,8 @@ import 'test_platform.dart';
 import 'environment.dart';
 import 'utils.dart';
 
-class TestsCommand extends Command<bool> {
-  TestsCommand() {
+class TestCommand extends Command<bool> {
+  TestCommand() {
     argParser
       ..addMultiOption(
         'target',
@@ -32,6 +32,13 @@ class TestsCommand extends Command<bool> {
         help: 'Pauses the browser before running a test, giving you an '
             'opportunity to add breakpoints or inspect loaded code before '
             'running the code.',
+      )
+      ..addFlag(
+        'update-screenshot-goldens',
+        defaultsTo: false,
+        help: 'When running screenshot tests writes them to the file system into '
+            '.dart_tool/goldens. Use this option to bulk-update all screenshots, '
+            'for example, when a new browser version affects pixels.',
       );
 
     addChromeVersionOption(argParser);
@@ -47,7 +54,7 @@ class TestsCommand extends Command<bool> {
   Future<bool> run() async {
     Chrome.version = chromeVersion;
 
-    _copyAhemFontIntoWebUi();
+    _copyTestFontsIntoWebUi();
     await _buildHostPage();
 
     final List<FilePath> targets =
@@ -73,6 +80,10 @@ class TestsCommand extends Command<bool> {
   /// See [ChromeInstallerCommand.chromeVersion].
   String get chromeVersion => argResults['chrome-version'];
 
+  /// When running screenshot tests writes them to the file system into
+  /// ".dart_tool/goldens".
+  bool get doUpdateScreenshotGoldens => argResults['update-screenshot-goldens'];
+
   Future<void> _runTargetTests(List<FilePath> targets) async {
     await _runTestBatch(targets, concurrency: 1, expectFailure: false);
     _checkExitCode();
@@ -234,7 +245,11 @@ class TestsCommand extends Command<bool> {
       ...testFiles.map((f) => f.relativeToWebUi).toList(),
     ];
     hack.registerPlatformPlugin(<Runtime>[Runtime.chrome], () {
-      return BrowserPlatform.start(root: io.Directory.current.path);
+      return BrowserPlatform.start(
+        root: io.Directory.current.path,
+        // It doesn't make sense to update a screenshot for a test that is expected to fail.
+        doUpdateScreenshotGoldens: !expectFailure && doUpdateScreenshotGoldens,
+      );
     });
 
     // We want to run tests with `web_ui` as a working directory.
@@ -257,15 +272,20 @@ class TestsCommand extends Command<bool> {
   }
 }
 
-void _copyAhemFontIntoWebUi() {
-  final io.File sourceAhemTtf = io.File(path.join(
-      environment.flutterDirectory.path,
-      'third_party',
-      'txt',
-      'third_party',
-      'fonts',
-      'ahem.ttf'));
-  final String destinationAhemTtfPath =
-      path.join(environment.webUiRootDir.path, 'lib', 'assets', 'ahem.ttf');
-  sourceAhemTtf.copySync(destinationAhemTtfPath);
+const List<String> _kTestFonts = <String>['ahem.ttf', 'Roboto-Regular.ttf'];
+
+void _copyTestFontsIntoWebUi() {
+  final String fontsPath = path.join(
+    environment.flutterDirectory.path,
+    'third_party',
+    'txt',
+    'third_party',
+    'fonts',
+  );
+
+  for (String fontFile in _kTestFonts) {
+    final io.File sourceTtf = io.File(path.join(fontsPath, fontFile));
+    final String destinationTtfPath = path.join(environment.webUiRootDir.path, 'lib', 'assets', fontFile);
+    sourceTtf.copySync(destinationTtfPath);
+  }
 }

lib/web_ui/lib/assets/.gitignore

@@ -1 +1 @@
-ahem.ttf
+*.ttf

lib/web_ui/lib/src/engine/text/font_collection.dart

@@ -4,8 +4,10 @@
 
 part of engine;
 
-const String _testFontFamily = 'Ahem';
-const String _testFontUrl = 'packages/ui/assets/ahem.ttf';
+const String _ahemFontFamily = 'Ahem';
+const String _ahemFontUrl = 'packages/ui/assets/ahem.ttf';
+const String _robotoFontFamily = 'Roboto';
+const String _robotoFontUrl = 'packages/ui/assets/Roboto-Regular.ttf';
 
 /// This class is responsible for registering and loading fonts.
 ///
@@ -75,7 +77,9 @@ class FontCollection {
   void debugRegisterTestFonts() {
     _testFontManager = _FontManager();
     _testFontManager.registerAsset(
-        _testFontFamily, 'url($_testFontUrl)', const <String, String>{});
+        _ahemFontFamily, 'url($_ahemFontUrl)', const <String, String>{});
+    _testFontManager.registerAsset(
+        _robotoFontFamily, 'url($_robotoFontUrl)', const <String, String>{});
   }
 
   /// Returns a [Future] that completes when the registered fonts are loaded

lib/web_ui/test/golden_tests/golden_success_smoke_test.dart

@@ -6,10 +6,15 @@ import 'dart:html' as html;
 
 import 'package:test/test.dart';
 import 'package:ui/ui.dart';
+import 'package:ui/src/engine.dart';
 import 'package:web_engine_tester/golden_tester.dart';
 
-void main() {
+void main() async {
+  debugEmulateFlutterTesterEnvironment = true;
+  await webOnlyInitializePlatform(assetManager: WebOnlyMockAssetManager());
+
   test('screenshot test reports success', () async {
+    html.document.body.style.fontFamily = 'Roboto';
     html.document.body.innerHtml = 'Hello world!';
     await matchGoldenFile('__local__/smoke_test.png', region: Rect.fromLTWH(0, 0, 320, 200));
   });