[tool] Adds --wasm flag to the drive-examples command (flutter#7162)

I was unsure if we wanted to add a new platform option for this or add a `--wasm` flag to the command. Adding a `--wasm` flag seems more complicated since we would probably want to add extra handling around proper use of the flag, whereas adding a `web-wasm` platform should require no additional checks.

This is in preparation for flutter/flutter#151664

Author: Rexios80

script/tool/lib/src/common/core.dart

@@ -37,6 +37,9 @@ const String kEnableExperiment = 'enable-experiment';
 /// land (e.g., dependency overrides in federated plugin combination PRs).
 const String kDoNotLandWarning = 'DO NOT MERGE';
 
+/// Key for enabling web WASM compilation
+const String kWebWasmFlag = 'wasm';
+
 /// Target platforms supported by Flutter.
 // ignore: public_member_api_docs
 enum FlutterPlatform { android, ios, linux, macos, web, windows }

script/tool/lib/src/drive_examples_command.dart

@@ -13,7 +13,7 @@ import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
 import 'common/repository_package.dart';
 
-const int _exitNoPlatformFlags = 2;
+const int _exitInvalidArgs = 2;
 const int _exitNoAvailableDevice = 3;
 
 // From https://flutter.dev/to/integration-test-on-web
@@ -40,6 +40,8 @@ class DriveExamplesCommand extends PackageLoopingCommand {
         help: 'Runs the web implementation of the examples');
     argParser.addFlag(platformWindows,
         help: 'Runs the Windows implementation of the examples');
+    argParser.addFlag(kWebWasmFlag,
+        help: 'Compile to WebAssembly rather than JavaScript');
     argParser.addOption(
       kEnableExperiment,
       defaultsTo: '',
@@ -84,7 +86,7 @@ class DriveExamplesCommand extends PackageLoopingCommand {
       printError(
           'Exactly one of ${platformSwitches.map((String platform) => '--$platform').join(', ')} '
           'must be specified.');
-      throw ToolExit(_exitNoPlatformFlags);
+      throw ToolExit(_exitInvalidArgs);
     }
 
     String? androidDevice;
@@ -107,22 +109,31 @@ class DriveExamplesCommand extends PackageLoopingCommand {
       iOSDevice = devices.first;
     }
 
+    final bool useWasm = getBoolArg(kWebWasmFlag);
+    final bool hasPlatformWeb = getBoolArg(platformWeb);
+    if (useWasm && !hasPlatformWeb) {
+      printError('--wasm is only supported on the web platform');
+      throw ToolExit(_exitInvalidArgs);
+    }
+
     _targetDeviceFlags = <String, List<String>>{
       if (getBoolArg(platformAndroid))
         platformAndroid: <String>['-d', androidDevice!],
       if (getBoolArg(platformIOS)) platformIOS: <String>['-d', iOSDevice!],
       if (getBoolArg(platformLinux)) platformLinux: <String>['-d', 'linux'],
       if (getBoolArg(platformMacOS)) platformMacOS: <String>['-d', 'macos'],
-      if (getBoolArg(platformWeb))
+      if (hasPlatformWeb)
         platformWeb: <String>[
           '-d',
           'web-server',
           '--web-port=7357',
           '--browser-name=chrome',
+          if (useWasm)
+            '--wasm'
           // TODO(dit): Clean this up, https://github.com/flutter/flutter/issues/151869
-          if (platform.environment['CHANNEL']?.toLowerCase() == 'master')
-            '--web-renderer=canvaskit',
-          if (platform.environment['CHANNEL']?.toLowerCase() != 'master')
+          else if (platform.environment['CHANNEL']?.toLowerCase() == 'master')
+            '--web-renderer=canvaskit'
+          else
             '--web-renderer=html',
           if (platform.environment.containsKey('CHROME_EXECUTABLE'))
             '--chrome-binary=${platform.environment['CHROME_EXECUTABLE']}',

script/tool/test/drive_examples_command_test.dart

@@ -89,6 +89,24 @@ void main() {
       );
     });
 
+    test('fails if wasm flag is present but not web platform', () async {
+      setMockFlutterDevicesOutput();
+      Error? commandError;
+      final List<String> output = await runCapturingPrint(
+          runner, <String>['drive-examples', '--android', '--wasm'],
+          errorHandler: (Error e) {
+        commandError = e;
+      });
+
+      expect(commandError, isA<ToolExit>());
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('--wasm is only supported on the web platform'),
+        ]),
+      );
+    });
+
     test('fails if multiple platforms are provided', () async {
       setMockFlutterDevicesOutput();
       Error? commandError;
@@ -691,6 +709,57 @@ void main() {
           ]));
     });
 
+    test('drives a web plugin compiled to WASM', () async {
+      final RepositoryPackage plugin = createFakePlugin(
+        'plugin',
+        packagesDir,
+        extraFiles: <String>[
+          'example/integration_test/plugin_test.dart',
+          'example/test_driver/integration_test.dart',
+          'example/web/index.html',
+        ],
+        platformSupport: <String, PlatformDetails>{
+          platformWeb: const PlatformDetails(PlatformSupport.inline),
+        },
+      );
+
+      final Directory pluginExampleDirectory = getExampleDir(plugin);
+
+      final List<String> output = await runCapturingPrint(runner, <String>[
+        'drive-examples',
+        '--web',
+        '--wasm',
+      ]);
+
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Running for plugin'),
+          contains('No issues found!'),
+        ]),
+      );
+
+      expect(
+          processRunner.recordedCalls,
+          orderedEquals(<ProcessCall>[
+            ProcessCall(
+                getFlutterCommand(mockPlatform),
+                const <String>[
+                  'drive',
+                  '-d',
+                  'web-server',
+                  '--web-port=7357',
+                  '--browser-name=chrome',
+                  '--wasm',
+                  '--driver',
+                  'test_driver/integration_test.dart',
+                  '--target',
+                  'integration_test/plugin_test.dart',
+                ],
+                pluginExampleDirectory.path),
+          ]));
+    });
+
     // TODO(dit): Clean this up, https://github.com/flutter/flutter/issues/151869
     test('drives a web plugin (html renderer in stable)', () async {
       // Override the platform to simulate CHANNEL: stable