[flutter_plugin_tools] Add a command to lint Android code (#4206)

Adds a new `lint-android` command to run `gradlew lint` on Android plugins.

Also standardizes the names of the Cirrus tasks that run all the build and platform-specific (i.e., not Dart unit test) tests for each platform, as they were getting unnecessarily long and complex in some cases.

Fixes https://github.com/flutter/flutter/issues/87071

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

@@ -0,0 +1,57 @@
+// 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 'process_runner.dart';
+
+const String _gradleWrapperWindows = 'gradlew.bat';
+const String _gradleWrapperNonWindows = 'gradlew';
+
+/// A utility class for interacting with Gradle projects.
+class GradleProject {
+  /// Creates an instance that runs commands for [project] with the given
+  /// [processRunner].
+  ///
+  /// If [log] is true, commands run by this instance will long various status
+  /// messages.
+  GradleProject(
+    this.flutterProject, {
+    this.processRunner = const ProcessRunner(),
+    this.platform = const LocalPlatform(),
+  });
+
+  /// The directory of a Flutter project to run Gradle commands in.
+  final Directory flutterProject;
+
+  /// The [ProcessRunner] used to run commands. Overridable for testing.
+  final ProcessRunner processRunner;
+
+  /// The platform that commands are being run on.
+  final Platform platform;
+
+  /// The project's 'android' directory.
+  Directory get androidDirectory => flutterProject.childDirectory('android');
+
+  /// The path to the Gradle wrapper file for the project.
+  File get gradleWrapper => androidDirectory.childFile(
+      platform.isWindows ? _gradleWrapperWindows : _gradleWrapperNonWindows);
+
+  /// Whether or not the project is ready to have Gradle commands run on it
+  /// (i.e., whether the `flutter` tool has generated the necessary files).
+  bool isConfigured() => gradleWrapper.existsSync();
+
+  /// Runs a `gradlew` command with the given parameters.
+  Future<int> runCommand(
+    String target, {
+    List<String> arguments = const <String>[],
+  }) {
+    return processRunner.runAndStream(
+      gradleWrapper.path,
+      <String>[target, ...arguments],
+      workingDir: androidDirectory,
+    );
+  }
+}

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

@@ -15,7 +15,7 @@ const String _xcRunCommand = 'xcrun';
 
 /// A utility class for interacting with the installed version of Xcode.
 class Xcode {
-  /// Creates an instance that runs commends with the given [processRunner].
+  /// Creates an instance that runs commands with the given [processRunner].
   ///
   /// If [log] is true, commands run by this instance will long various status
   /// messages.

script/tool/lib/src/firebase_test_lab_command.dart

@@ -10,6 +10,7 @@ import 'package:platform/platform.dart';
 import 'package:uuid/uuid.dart';
 
 import 'common/core.dart';
+import 'common/gradle.dart';
 import 'common/package_looping_command.dart';
 import 'common/process_runner.dart';
 
@@ -74,8 +75,6 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
       'Runs tests in test_instrumentation folder using the '
       'instrumentation_test package.';
 
-  static const String _gradleWrapper = 'gradlew';
-
   bool _firebaseProjectConfigured = false;
 
   Future<void> _configureFirebaseProject() async {
@@ -138,13 +137,15 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
     }
 
     // Ensures that gradle wrapper exists
-    if (!await _ensureGradleWrapperExists(androidDirectory)) {
+    final GradleProject project = GradleProject(exampleDirectory,
+        processRunner: processRunner, platform: platform);
+    if (!await _ensureGradleWrapperExists(project)) {
       return PackageResult.fail(<String>['Unable to build example apk']);
     }
 
     await _configureFirebaseProject();
 
-    if (!await _runGradle(androidDirectory, 'app:assembleAndroidTest')) {
+    if (!await _runGradle(project, 'app:assembleAndroidTest')) {
       return PackageResult.fail(<String>['Unable to assemble androidTest']);
     }
 
@@ -156,8 +157,7 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
     for (final File test in _findIntegrationTestFiles(package)) {
       final String testName = getRelativePosixPath(test, from: package);
       print('Testing $testName...');
-      if (!await _runGradle(androidDirectory, 'app:assembleDebug',
-          testFile: test)) {
+      if (!await _runGradle(project, 'app:assembleDebug', testFile: test)) {
         printError('Could not build $testName');
         errors.add('$testName failed to build');
         continue;
@@ -204,12 +204,12 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
         : PackageResult.fail(errors);
   }
 
-  /// Checks that 'gradlew' exists in [androidDirectory], and if not runs a
+  /// Checks that Gradle has been configured for [project], and if not runs a
   /// Flutter build to generate it.
   ///
   /// Returns true if either gradlew was already present, or the build succeeds.
-  Future<bool> _ensureGradleWrapperExists(Directory androidDirectory) async {
-    if (!androidDirectory.childFile(_gradleWrapper).existsSync()) {
+  Future<bool> _ensureGradleWrapperExists(GradleProject project) async {
+    if (!project.isConfigured()) {
       print('Running flutter build apk...');
       final String experiment = getStringArg(kEnableExperiment);
       final int exitCode = await processRunner.runAndStream(
@@ -219,7 +219,7 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
             'apk',
             if (experiment.isNotEmpty) '--enable-experiment=$experiment',
           ],
-          workingDir: androidDirectory);
+          workingDir: project.androidDirectory);
 
       if (exitCode != 0) {
         return false;
@@ -228,15 +228,15 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
     return true;
   }
 
-  /// Builds [target] using 'gradlew' in the given [directory]. Assumes
-  /// 'gradlew' already exists.
+  /// Builds [target] using Gradle in the given [project]. Assumes Gradle is
+  /// already configured.
   ///
   /// [testFile] optionally does the Flutter build with the given test file as
   /// the build target.
   ///
   /// Returns true if the command succeeds.
   Future<bool> _runGradle(
-    Directory directory,
+    GradleProject project,
     String target, {
     File? testFile,
   }) async {
@@ -245,17 +245,15 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
         ? Uri.encodeComponent('--enable-experiment=$experiment')
         : null;
 
-    final int exitCode = await processRunner.runAndStream(
-        directory.childFile(_gradleWrapper).path,
-        <String>[
-          target,
-          '-Pverbose=true',
-          if (testFile != null) '-Ptarget=${testFile.path}',
-          if (extraOptions != null) '-Pextra-front-end-options=$extraOptions',
-          if (extraOptions != null)
-            '-Pextra-gen-snapshot-options=$extraOptions',
-        ],
-        workingDir: directory);
+    final int exitCode = await project.runCommand(
+      target,
+      arguments: <String>[
+        '-Pverbose=true',
+        if (testFile != null) '-Ptarget=${testFile.path}',
+        if (extraOptions != null) '-Pextra-front-end-options=$extraOptions',
+        if (extraOptions != null) '-Pextra-gen-snapshot-options=$extraOptions',
+      ],
+    );
 
     if (exitCode != 0) {
       return false;

script/tool/lib/src/lint_android_command.dart

@@ -0,0 +1,61 @@
+// 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:flutter_plugin_tools/src/common/plugin_utils.dart';
+import 'package:platform/platform.dart';
+
+import 'common/core.dart';
+import 'common/gradle.dart';
+import 'common/package_looping_command.dart';
+import 'common/process_runner.dart';
+
+/// Lint the CocoaPod podspecs and run unit tests.
+///
+/// See https://guides.cocoapods.org/terminal/commands.html#pod_lib_lint.
+class LintAndroidCommand extends PackageLoopingCommand {
+  /// Creates an instance of the linter command.
+  LintAndroidCommand(
+    Directory packagesDir, {
+    ProcessRunner processRunner = const ProcessRunner(),
+    Platform platform = const LocalPlatform(),
+  }) : super(packagesDir, processRunner: processRunner, platform: platform);
+
+  @override
+  final String name = 'lint-android';
+
+  @override
+  final String description = 'Runs "gradlew lint" on Android plugins.\n\n'
+      'Requires the example to have been build at least once before running.';
+
+  @override
+  Future<PackageResult> runForPackage(Directory package) async {
+    if (!pluginSupportsPlatform(kPlatformAndroid, package,
+        requiredMode: PlatformSupport.inline)) {
+      return PackageResult.skip(
+          'Plugin does not have an Android implemenatation.');
+    }
+
+    final Directory exampleDirectory = package.childDirectory('example');
+    final GradleProject project = GradleProject(exampleDirectory,
+        processRunner: processRunner, platform: platform);
+
+    if (!project.isConfigured()) {
+      return PackageResult.fail(<String>['Build example before linting']);
+    }
+
+    final String packageName = package.basename;
+
+    // Only lint one build mode to avoid extra work.
+    // Only lint the plugin project itself, to avoid failing due to errors in
+    // dependencies.
+    //
+    // TODO(stuartmorgan): Consider adding an XML parser to read and summarize
+    // all results. Currently, only the first three errors will be shown inline,
+    // and the rest have to be checked via the CI-uploaded artifact.
+    final int exitCode = await project.runCommand('$packageName:lintDebug');
+
+    return exitCode == 0 ? PackageResult.success() : PackageResult.fail();
+  }
+}

script/tool/lib/src/main.dart

@@ -16,6 +16,7 @@ import 'drive_examples_command.dart';
 import 'firebase_test_lab_command.dart';
 import 'format_command.dart';
 import 'license_check_command.dart';
+import 'lint_android_command.dart';
 import 'lint_podspecs_command.dart';
 import 'list_command.dart';
 import 'native_test_command.dart';
@@ -51,6 +52,7 @@ void main(List<String> args) {
     ..addCommand(FirebaseTestLabCommand(packagesDir))
     ..addCommand(FormatCommand(packagesDir))
     ..addCommand(LicenseCheckCommand(packagesDir))
+    ..addCommand(LintAndroidCommand(packagesDir))
     ..addCommand(LintPodspecsCommand(packagesDir))
     ..addCommand(ListCommand(packagesDir))
     ..addCommand(NativeTestCommand(packagesDir))

script/tool/lib/src/native_test_command.dart

@@ -6,6 +6,7 @@ import 'package:file/file.dart';
 import 'package:platform/platform.dart';
 
 import 'common/core.dart';
+import 'common/gradle.dart';
 import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
 import 'common/process_runner.dart';
@@ -47,8 +48,6 @@ class NativeTestCommand extends PackageLoopingCommand {
         help: 'Runs native integration (UI) tests', defaultsTo: true);
   }
 
-  static const String _gradleWrapper = 'gradlew';
-
   // The device destination flags for iOS tests.
   List<String> _iosDestinationFlags = <String>[];
 
@@ -243,9 +242,12 @@ this command.
       final String exampleName = getPackageDescription(example);
       _printRunningExampleTestsMessage(example, 'Android');
 
-      final Directory androidDirectory = example.childDirectory('android');
-      final File gradleFile = androidDirectory.childFile(_gradleWrapper);
-      if (!gradleFile.existsSync()) {
+      final GradleProject project = GradleProject(
+        example,
+        processRunner: processRunner,
+        platform: platform,
+      );
+      if (!project.isConfigured()) {
         printError('ERROR: Run "flutter build apk" on $exampleName, or run '
             'this tool\'s "build-examples --apk" command, '
             'before executing tests.');
@@ -256,9 +258,7 @@ this command.
 
       if (runUnitTests) {
         print('Running unit tests...');
-        final int exitCode = await processRunner.runAndStream(
-            gradleFile.path, <String>['testDebugUnitTest'],
-            workingDir: androidDirectory);
+        final int exitCode = await project.runCommand('testDebugUnitTest');
         if (exitCode != 0) {
           printError('$exampleName unit tests failed.');
           failed = true;
@@ -275,13 +275,12 @@ this command.
             'notAnnotation=io.flutter.plugins.DartIntegrationTest';
 
         print('Running integration tests...');
-        final int exitCode = await processRunner.runAndStream(
-            gradleFile.path,
-            <String>[
-              'app:connectedAndroidTest',
-              '-Pandroid.testInstrumentationRunnerArguments.$filter',
-            ],
-            workingDir: androidDirectory);
+        final int exitCode = await project.runCommand(
+          'app:connectedAndroidTest',
+          arguments: <String>[
+            '-Pandroid.testInstrumentationRunnerArguments.$filter',
+          ],
+        );
         if (exitCode != 0) {
           printError('$exampleName integration tests failed.');
           failed = true;