[web] Reland - Switch flutter tool web-renderer default for web to auto (#73595)

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -461,7 +461,7 @@ abstract class FlutterCommand extends Command<void> {
 
   void usesWebRendererOption() {
     argParser.addOption('web-renderer',
-      defaultsTo: 'html',
+      defaultsTo: 'auto',
       allowed: <String>['auto', 'canvaskit', 'html'],
       help: 'The renderer implementation to use when building for the web. Possible values are:\n'
             'html - always use the HTML renderer. This renderer uses a combination of HTML, CSS, SVG, 2D Canvas, and WebGL. This is the default.\n'
@@ -902,7 +902,7 @@ abstract class FlutterCommand extends Command<void> {
         ? stringsArg(FlutterOptions.kDartDefinesOption)
         : <String>[];
 
-    if (argParser.options.containsKey('web-renderer') && argResults.wasParsed('web-renderer')) {
+    if (argParser.options.containsKey('web-renderer')) {
       dartDefines = updateDartDefines(dartDefines, stringArg('web-renderer'));
     }
 

packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart

@@ -11,6 +11,7 @@ import 'package:flutter_tools/src/build_system/build_system.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/build.dart';
 import 'package:flutter_tools/src/commands/build_web.dart';
+import 'package:flutter_tools/src/runner/flutter_command.dart';
 import 'package:flutter_tools/src/dart/pub.dart';
 import 'package:flutter_tools/src/features.dart';
 import 'package:flutter_tools/src/globals.dart' as globals;
@@ -97,6 +98,58 @@ void main() {
   testUsingContext('Builds a web bundle - end to end', () async {
     final BuildCommand buildCommand = BuildCommand();
     final CommandRunner<void> runner = createTestCommandRunner(buildCommand);
+    setupFileSystemForEndToEndTest(fileSystem);
+    await runner.run(<String>['build', 'web']);
+
+    expect(fileSystem.file(fileSystem.path.join('lib', 'generated_plugin_registrant.dart')).existsSync(), true);
+  }, overrides: <Type, Generator>{
+    Platform: () => fakePlatform,
+    FileSystem: () => fileSystem,
+    FeatureFlags: () => TestFeatureFlags(isWebEnabled: true),
+    Pub: () => MockPub(),
+    ProcessManager: () => FakeProcessManager.any(),
+    BuildSystem: () => MockBuildSystem(),
+  });
+
+  testUsingContext('hidden if feature flag is not enabled', () async {
+    expect(BuildWebCommand(verboseHelp: false).hidden, true);
+  }, overrides: <Type, Generator>{
+    Platform: () => fakePlatform,
+    FileSystem: () => fileSystem,
+    FeatureFlags: () => TestFeatureFlags(isWebEnabled: false),
+    Pub: () => MockPub(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('not hidden if feature flag is enabled', () async {
+    expect(BuildWebCommand(verboseHelp: false).hidden, false);
+  }, overrides: <Type, Generator>{
+    Platform: () => fakePlatform,
+    FileSystem: () => fileSystem,
+    FeatureFlags: () => TestFeatureFlags(isWebEnabled: true),
+    Pub: () => MockPub(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('Defaults to web renderer auto mode when no option is specified', () async {
+    final TestWebBuildCommand buildCommand = TestWebBuildCommand();
+    final CommandRunner<void> runner = createTestCommandRunner(buildCommand);
+    setupFileSystemForEndToEndTest(fileSystem);
+    await runner.run(<String>['build', 'web']);
+    final BuildInfo buildInfo =
+        await buildCommand.webCommand.getBuildInfo(forcedBuildMode: BuildMode.debug);
+    expect(buildInfo.dartDefines, contains('FLUTTER_WEB_AUTO_DETECT=true'));
+  }, overrides: <Type, Generator>{
+    Platform: () => fakePlatform,
+    FileSystem: () => fileSystem,
+    FeatureFlags: () => TestFeatureFlags(isWebEnabled: true),
+    Pub: () => MockPub(),
+    ProcessManager: () => FakeProcessManager.any(),
+    BuildSystem: () => MockBuildSystem(),
+  });
+}
+
+void setupFileSystemForEndToEndTest(FileSystem fileSystem) {
   final List<String> dependencies = <String>[
     fileSystem.path.join('packages', 'flutter_tools', 'lib', 'src', 'build_system', 'targets', 'web.dart'),
     fileSystem.path.join('bin', 'cache', 'flutter_web_sdk'),
@@ -150,38 +203,25 @@ class UrlLauncherPlugin {}
   when(globals.buildSystem.build(any, any)).thenAnswer((Invocation invocation) async {
     return BuildResult(success: true);
   });
-    await runner.run(<String>['build', 'web']);
-
-    expect(fileSystem.file(fileSystem.path.join('lib', 'generated_plugin_registrant.dart')).existsSync(), true);
-  }, overrides: <Type, Generator>{
-    Platform: () => fakePlatform,
-    FileSystem: () => fileSystem,
-    FeatureFlags: () => TestFeatureFlags(isWebEnabled: true),
-    Pub: () => MockPub(),
-    ProcessManager: () => FakeProcessManager.any(),
-    BuildSystem: () => MockBuildSystem(),
-  });
-
-  testUsingContext('hidden if feature flag is not enabled', () async {
-    expect(BuildWebCommand(verboseHelp: false).hidden, true);
-  }, overrides: <Type, Generator>{
-    Platform: () => fakePlatform,
-    FileSystem: () => fileSystem,
-    FeatureFlags: () => TestFeatureFlags(isWebEnabled: false),
-    Pub: () => MockPub(),
-    ProcessManager: () => FakeProcessManager.any(),
-  });
-
-  testUsingContext('not hidden if feature flag is enabled', () async {
-    expect(BuildWebCommand(verboseHelp: false).hidden, false);
-  }, overrides: <Type, Generator>{
-    Platform: () => fakePlatform,
-    FileSystem: () => fileSystem,
-    FeatureFlags: () => TestFeatureFlags(isWebEnabled: true),
-    Pub: () => MockPub(),
-    ProcessManager: () => FakeProcessManager.any(),
-  });
 }
 
 class MockBuildSystem extends Mock implements BuildSystem {}
 class MockPub extends Mock implements Pub {}
+
+class TestWebBuildCommand extends FlutterCommand {
+  TestWebBuildCommand({ bool verboseHelp = false }) :
+    webCommand = BuildWebCommand(verboseHelp: verboseHelp) {
+    addSubcommand(webCommand);
+  }
+
+  final BuildWebCommand webCommand;
+
+  @override
+  final String name = 'build';
+
+  @override
+  final String description = 'Build a test executable app.';
+
+  @override
+  Future<FlutterCommandResult> runCommand() async => null;
+}