[flutter_plugin_tool] Add custom-test command (#5058)

script/tool/lib/src/custom_test_command.dart

@@ -0,0 +1,77 @@
+// Copyright 2013 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 'package:file/file.dart';
+import 'package:platform/platform.dart';
+
+import 'common/package_looping_command.dart';
+import 'common/process_runner.dart';
+import 'common/repository_package.dart';
+
+const String _scriptName = 'run_tests.dart';
+const String _legacyScriptName = 'run_tests.sh';
+
+/// A command to run custom, package-local tests on packages.
+///
+/// This is an escape hatch for adding tests that this tooling doesn't support.
+/// It should be used sparingly; prefer instead to add functionality to this
+/// tooling to eliminate the need for bespoke tests.
+class CustomTestCommand extends PackageLoopingCommand {
+  /// Creates a custom test command instance.
+  CustomTestCommand(
+    Directory packagesDir, {
+    ProcessRunner processRunner = const ProcessRunner(),
+    Platform platform = const LocalPlatform(),
+  }) : super(packagesDir, processRunner: processRunner, platform: platform);
+
+  @override
+  final String name = 'custom-test';
+
+  @override
+  final String description = 'Runs package-specific custom tests defined in '
+      'a package\'s tool/$_scriptName file.\n\n'
+      'This command requires "dart" to be in your path.';
+
+  @override
+  Future<PackageResult> runForPackage(RepositoryPackage package) async {
+    final File script =
+        package.directory.childDirectory('tool').childFile(_scriptName);
+    final File legacyScript = package.directory.childFile(_legacyScriptName);
+    String? customSkipReason;
+    bool ranTests = false;
+
+    // Run the custom Dart script if presest.
+    if (script.existsSync()) {
+      final int exitCode = await processRunner.runAndStream(
+          'dart', <String>['run', 'tool/$_scriptName'],
+          workingDir: package.directory);
+      if (exitCode != 0) {
+        return PackageResult.fail();
+      }
+      ranTests = true;
+    }
+
+    // Run the legacy script if present.
+    if (legacyScript.existsSync()) {
+      if (platform.isWindows) {
+        customSkipReason = '$_legacyScriptName is not supported on Windows. '
+            'Please migrate to $_scriptName.';
+      } else {
+        final int exitCode = await processRunner.runAndStream(
+            legacyScript.path, <String>[],
+            workingDir: package.directory);
+        if (exitCode != 0) {
+          return PackageResult.fail();
+        }
+        ranTests = true;
+      }
+    }
+
+    if (!ranTests) {
+      return PackageResult.skip(customSkipReason ?? 'No custom tests');
+    }
+
+    return PackageResult.success();
+  }
+}

script/tool/lib/src/main.dart

@@ -12,6 +12,7 @@ import 'analyze_command.dart';
 import 'build_examples_command.dart';
 import 'common/core.dart';
 import 'create_all_plugins_app_command.dart';
+import 'custom_test_command.dart';
 import 'drive_examples_command.dart';
 import 'federation_safety_check_command.dart';
 import 'firebase_test_lab_command.dart';
@@ -50,6 +51,7 @@ void main(List<String> args) {
     ..addCommand(AnalyzeCommand(packagesDir))
     ..addCommand(BuildExamplesCommand(packagesDir))
     ..addCommand(CreateAllPluginsAppCommand(packagesDir))
+    ..addCommand(CustomTestCommand(packagesDir))
     ..addCommand(DriveExamplesCommand(packagesDir))
     ..addCommand(FederationSafetyCheckCommand(packagesDir))
     ..addCommand(FirebaseTestLabCommand(packagesDir))