add flavor-conditional asset bundling support to `flutter test` (#140944)

Fixes https://github.com/flutter/flutter/issues/140932

packages/flutter_tools/lib/src/commands/test.dart

@@ -347,7 +347,7 @@ class TestCommand extends FlutterCommand with DeviceBasedDevelopmentArtifacts {
 
     String? testAssetDirectory;
     if (buildTestAssets) {
-      await _buildTestAsset();
+      await _buildTestAsset(flavor: buildInfo.flavor);
       testAssetDirectory = globals.fs.path.
         join(flutterProject.directory.path, 'build', 'unit_test_assets');
     }
@@ -563,9 +563,14 @@ class TestCommand extends FlutterCommand with DeviceBasedDevelopmentArtifacts {
         .replace(query: queryPart.isEmpty ? null : queryPart);
   }
 
-  Future<void> _buildTestAsset() async {
+  Future<void> _buildTestAsset({
+    required String? flavor,
+  }) async {
     final AssetBundle assetBundle = AssetBundleFactory.instance.createBundle();
-    final int build = await assetBundle.build(packagesPath: '.packages');
+    final int build = await assetBundle.build(
+      packagesPath: '.packages',
+      flavor: flavor,
+    );
     if (build != 0) {
       throwToolExit('Error: Failed to build asset bundle');
     }

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

@@ -888,6 +888,45 @@ dev_dependencies:
     DeviceManager: () => _FakeDeviceManager(<Device>[]),
   });
 
+  testUsingContext('builds asset bundle using --flavor', () async {
+    final FakeFlutterTestRunner testRunner = FakeFlutterTestRunner(0);
+    fs.file('vanilla.txt').writeAsStringSync('vanilla');
+    fs.file('orange.txt').writeAsStringSync('orange');
+    fs.file('pubspec.yaml').writeAsStringSync('''
+flutter:
+  assets:
+    - path: vanilla.txt
+      flavors:
+        - vanilla
+    - path: orange.txt
+      flavors:
+        - orange
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  integration_test:
+    sdk: flutter''');
+    final TestCommand testCommand = TestCommand(testRunner: testRunner);
+    final CommandRunner<void> commandRunner = createTestCommandRunner(testCommand);
+
+    await commandRunner.run(const <String>[
+      'test',
+      '--no-pub',
+      '--flavor',
+      'vanilla',
+    ]);
+
+    final bool vanillaExists = await fs.isFile(globals.fs.path.join('build', 'unit_test_assets', 'vanilla.txt'));
+    expect(vanillaExists, true, reason: 'vanilla.txt should be bundled');
+    final bool orangeExists = await fs.isFile(globals.fs.path.join('build', 'unit_test_assets', 'orange.txt'));
+    expect(orangeExists, false, reason: 'orange.txt should not be bundled');
+
+  }, overrides: <Type, Generator>{
+    FileSystem: () => fs,
+    ProcessManager: () => FakeProcessManager.any(),
+    DeviceManager: () => _FakeDeviceManager(<Device>[]),
+  });
+
   testUsingContext("Don't build the asset manifest if --no-test-assets if informed", () async {
     final FakeFlutterTestRunner testRunner = FakeFlutterTestRunner(0);