Add vmservice for android build options (#123034)

https://github.com/flutter/flutter/issues/120408

packages/flutter_tools/gradle/flutter.gradle

@@ -695,6 +695,28 @@ class FlutterPlugin implements Plugin<Project> {
         }
     }
 
+    // Add a task that can be called on flutter projects that prints the available build variants
+    // in gradle.
+    //
+    // This task prints variants in this format:
+    //
+    // BuildVariant: debug
+    // BuildVariant: release
+    // BuildVariant: profile
+    //
+    // Format of the output of this task is used by `AndroidProject.getBuildVariants`.
+    private static void addTaskForPrintBuildVariants(Project project) {
+        // Warning: The name of this task is used by `AndroidProject.getBuildVariants`.
+        project.tasks.register("printBuildVariants") {
+            description "Prints out all build variants for this Android project"
+            doLast {
+                project.android.applicationVariants.all { variant ->
+                    println "BuildVariant: ${variant.name}";
+                }
+            }
+        }
+    }
+
     /**
      * Returns a Flutter build mode suitable for the specified Android buildType.
      *
@@ -867,7 +889,9 @@ class FlutterPlugin implements Plugin<Project> {
         if (project.hasProperty('validate-deferred-components')) {
             validateDeferredComponentsValue = project.property('validate-deferred-components').toBoolean()
         }
+
         addTaskForJavaVersion(project)
+        addTaskForPrintBuildVariants(project)
         def targetPlatforms = getTargetPlatforms()
         def addFlutterDeps = { variant ->
             if (shouldSplitPerAbi()) {

packages/flutter_tools/lib/src/android/android_builder.dart

@@ -39,4 +39,7 @@ abstract class AndroidBuilder {
     bool deferredComponentsEnabled = false,
     bool configOnly = false,
   });
+
+  /// Returns a list of available build variant from the Android project.
+  Future<List<String>> getBuildVariants({required FlutterProject project});
 }

packages/flutter_tools/lib/src/android/android_sdk.dart

@@ -40,7 +40,7 @@ class AndroidSdk {
     reinitialize();
   }
 
-  static const String _javaHomeEnvironmentVariable = 'JAVA_HOME';
+  static const String javaHomeEnvironmentVariable = 'JAVA_HOME';
   static const String _javaExecutable = 'java';
 
   /// The Android SDK root directory.
@@ -462,10 +462,44 @@ class AndroidSdk {
     return versionString.split('_').first;
   }
 
-  /// Finds the java binary that is used for all operations across the tool.
+  /// A value that would be appropriate to use as JAVA_HOME.
   ///
-  /// First try Java bundled with Android Studio, then sniff JAVA_HOME, then fallback to PATH.
+  /// This method considers jdk in the following order:
+  /// * the JDK bundled with Android Studio, if one is found;
+  /// * the JAVA_HOME in the ambient environment, if set;
+  String? get javaHome {
+    return findJavaHome(
+      androidStudio: globals.androidStudio,
+      fileSystem: globals.fs,
+      operatingSystemUtils: globals.os,
+      platform: globals.platform,
+    );
+  }
+
+
+  static String? findJavaHome({
+    required AndroidStudio? androidStudio,
+    required FileSystem fileSystem,
+    required OperatingSystemUtils operatingSystemUtils,
+    required Platform platform,
+  }) {
+    if (androidStudio?.javaPath != null) {
+      globals.printTrace("Using Android Studio's java.");
+      return androidStudio!.javaPath!;
+    }
+
+    final String? javaHomeEnv = platform.environment[javaHomeEnvironmentVariable];
+    if (javaHomeEnv != null) {
+      globals.printTrace('Using JAVA_HOME from environment valuables.');
+      return javaHomeEnv;
+    }
+    return null;
+  }
+
+  /// Finds the java binary that is used for all operations across the tool.
   ///
+  /// This comes from [findJavaHome] if that method returns non-null;
+  /// otherwise, it gets from searching PATH.
   // TODO(andrewkolos): To prevent confusion when debugging Android-related
   // issues (see https://github.com/flutter/flutter/issues/122609 for an example),
   // this logic should be consistently followed by any Java-dependent operation
@@ -479,17 +513,15 @@ class AndroidSdk {
     required OperatingSystemUtils operatingSystemUtils,
     required Platform platform,
   }) {
-    if (androidStudio?.javaPath != null) {
-      globals.printTrace("Using Android Studio's java.");
-      return fileSystem.path.join(androidStudio!.javaPath!, 'bin', 'java');
-    }
+    final String? javaHome = findJavaHome(
+      androidStudio: androidStudio,
+      fileSystem: fileSystem,
+      operatingSystemUtils: operatingSystemUtils,
+      platform: platform,
+    );
 
-    final String? javaHomeEnv =
-        platform.environment[_javaHomeEnvironmentVariable];
-    if (javaHomeEnv != null) {
-      // Trust JAVA_HOME.
-      globals.printTrace('Using JAVA_HOME.');
-      return fileSystem.path.join(javaHomeEnv, 'bin', 'java');
+    if (javaHome != null) {
+      return fileSystem.path.join(javaHome, 'bin', 'java');
     }
 
     // Fallback to PATH based lookup.
@@ -528,8 +560,8 @@ class AndroidSdk {
       );
       if (javaBinary != null && globals.platform.environment['PATH'] != null) {
         _sdkManagerEnv!['PATH'] = globals.fs.path.dirname(javaBinary) +
-                                 globals.os.pathVarSeparator +
-                                 globals.platform.environment['PATH']!;
+                                  globals.os.pathVarSeparator +
+                                  globals.platform.environment['PATH']!;
       }
     }
     return _sdkManagerEnv!;

packages/flutter_tools/lib/src/android/gradle.dart

@@ -26,15 +26,28 @@ import '../build_info.dart';
 import '../cache.dart';
 import '../convert.dart';
 import '../flutter_manifest.dart';
+import '../globals.dart' as globals;
 import '../project.dart';
 import '../reporting/reporting.dart';
 import 'android_builder.dart';
-import 'android_studio.dart';
+import 'android_sdk.dart';
 import 'gradle_errors.dart';
 import 'gradle_utils.dart';
 import 'migrations/top_level_gradle_build_file_migration.dart';
 import 'multidex.dart';
 
+/// The regex to grab variant names from printVariants gradle task
+///
+/// The task is defined in flutter/packages/flutter_tools/gradle/flutter.gradle.
+///
+/// The expected output from the task should be similar to:
+///
+/// BuildVariant: debug
+/// BuildVariant: release
+/// BuildVariant: profile
+final RegExp _kBuildVariantRegex = RegExp('^BuildVariant: (?<$_kBuildVariantRegexGroupName>.*)\$');
+const String _kBuildVariantRegexGroupName = 'variant';
+
 /// The directory where the APK artifact is generated.
 Directory getApkDirectory(FlutterProject project) {
   return project.isModule
@@ -397,13 +410,14 @@ class AndroidGradleBuilder implements AndroidBuilder {
       ..start();
     int exitCode = 1;
     try {
+      final String? javaHome = globals.androidSdk?.javaHome;
       exitCode = await _processUtils.stream(
         command,
         workingDirectory: project.android.hostAppGradleRoot.path,
         allowReentrantFlutter: true,
         environment: <String, String>{
-          if (javaPath != null)
-            'JAVA_HOME': javaPath!,
+          if (javaHome != null)
+            AndroidSdk.javaHomeEnvironmentVariable: javaHome,
         },
         mapFunction: consumeLog,
       );
@@ -666,13 +680,14 @@ class AndroidGradleBuilder implements AndroidBuilder {
       ..start();
     RunResult result;
     try {
+      final String? javaHome = globals.androidSdk?.javaHome;
       result = await _processUtils.run(
         command,
         workingDirectory: project.android.hostAppGradleRoot.path,
         allowReentrantFlutter: true,
         environment: <String, String>{
-          if (javaPath != null)
-            'JAVA_HOME': javaPath!,
+          if (javaHome != null)
+            AndroidSdk.javaHomeEnvironmentVariable: javaHome,
         },
       );
     } finally {
@@ -702,6 +717,51 @@ class AndroidGradleBuilder implements AndroidBuilder {
       color: TerminalColor.green,
     );
   }
+
+  @override
+  Future<List<String>> getBuildVariants({required FlutterProject project}) async {
+    final Status status = _logger.startProgress(
+      "Running Gradle task 'printBuildVariants'...",
+    );
+    final List<String> command = <String>[
+      _gradleUtils.getExecutable(project),
+      '-q', // suppresses gradle output.
+      'printBuildVariants',
+    ];
+
+    final Stopwatch sw = Stopwatch()
+      ..start();
+    RunResult result;
+    try {
+      final String? javaHome = globals.androidSdk?.javaHome;
+      result = await _processUtils.run(
+        command,
+        workingDirectory: project.android.hostAppGradleRoot.path,
+        allowReentrantFlutter: true,
+        environment: <String, String>{
+          if (javaHome != null)
+            AndroidSdk.javaHomeEnvironmentVariable: javaHome,
+        },
+      );
+    } finally {
+      status.stop();
+    }
+    _usage.sendTiming('print', 'android build variants', sw.elapsed);
+
+    if (result.exitCode != 0) {
+      _logger.printStatus(result.stdout, wrap: false);
+      _logger.printError(result.stderr, wrap: false);
+      return const <String>[];
+    }
+    final List<String> options = <String>[];
+    for (final String line in LineSplitter.split(result.stdout)) {
+      final RegExpMatch? match = _kBuildVariantRegex.firstMatch(line);
+      if (match != null) {
+        options.add(match.namedGroup(_kBuildVariantRegexGroupName)!);
+      }
+    }
+    return options;
+  }
 }
 
 /// Prints how to consume the AAR from a host app.

packages/flutter_tools/lib/src/android/gradle_errors.dart

@@ -11,6 +11,7 @@ import '../base/terminal.dart';
 import '../globals.dart' as globals;
 import '../project.dart';
 import '../reporting/reporting.dart';
+import 'android_sdk.dart';
 import 'android_studio.dart';
 import 'gradle_utils.dart';
 import 'multidex.dart';
@@ -379,7 +380,7 @@ final GradleHandledError flavorUndefinedHandler = GradleHandledError(
       workingDirectory: project.android.hostAppGradleRoot.path,
       environment: <String, String>{
         if (javaPath != null)
-          'JAVA_HOME': javaPath!,
+          AndroidSdk.javaHomeEnvironmentVariable: javaPath!,
       },
     );
     // Extract build types and product flavors.

packages/flutter_tools/lib/src/flutter_cache.dart

@@ -7,6 +7,7 @@ import 'dart:async';
 import 'package:meta/meta.dart';
 import 'package:package_config/package_config.dart';
 
+import 'android/android_sdk.dart';
 import 'android/android_studio.dart';
 import 'base/common.dart';
 import 'base/error_handling_io.dart';
@@ -425,7 +426,7 @@ class AndroidMavenArtifacts extends ArtifactSet {
         ],
         environment: <String, String>{
           if (javaPath != null)
-            'JAVA_HOME': javaPath!,
+            AndroidSdk.javaHomeEnvironmentVariable: javaPath!,
         },
       );
       if (processResult.exitCode != 0) {

packages/flutter_tools/lib/src/project.dart

@@ -7,6 +7,7 @@ import 'package:xml/xml.dart';
 import 'package:yaml/yaml.dart';
 
 import '../src/convert.dart';
+import 'android/android_builder.dart';
 import 'android/gradle_utils.dart' as gradle;
 import 'base/common.dart';
 import 'base/error_handling_io.dart';
@@ -474,6 +475,13 @@ class AndroidProject extends FlutterProjectPlatform {
   /// Returns true if the current version of the Gradle plugin is supported.
   late final bool isSupportedVersion = _computeSupportedVersion();
 
+  Future<List<String>> getBuildVariants() async {
+    if (!existsSync() || androidBuilder == null) {
+      return const <String>[];
+    }
+    return androidBuilder!.getBuildVariants(project: parent);
+  }
+
   bool _computeSupportedVersion() {
     final FileSystem fileSystem = hostAppGradleRoot.fileSystem;
     final File plugin = hostAppGradleRoot.childFile(

packages/flutter_tools/lib/src/vmservice.dart

@@ -31,6 +31,17 @@ const String kScreenshotMethod = '_flutter.screenshot';
 const String kRenderFrameWithRasterStatsMethod = '_flutter.renderFrameWithRasterStats';
 const String kReloadAssetFonts = '_flutter.reloadAssetFonts';
 
+const String kFlutterToolAlias = 'Flutter Tools';
+
+const String kReloadSourcesServiceName = 'reloadSources';
+const String kHotRestartServiceName = 'hotRestart';
+const String kFlutterVersionServiceName = 'flutterVersion';
+const String kCompileExpressionServiceName = 'compileExpression';
+const String kFlutterMemoryInfoServiceName = 'flutterMemoryInfo';
+const String kFlutterGetSkSLServiceName = 'flutterGetSkSL';
+const String kFlutterGetIOSBuildOptionsServiceName = 'flutterGetIOSBuildOptions';
+const String kFlutterGetAndroidBuildVariantsServiceName = 'flutterGetAndroidBuildVariants';
+
 /// The error response code from an unrecoverable compilation failure.
 const int kIsolateReloadBarred = 1005;
 
@@ -196,7 +207,7 @@ Future<vm_service.VmService> setUpVmService({
   // all at the end of this method.
   final List<Future<vm_service.Success?>> registrationRequests = <Future<vm_service.Success?>>[];
   if (reloadSources != null) {
-    vmService.registerServiceCallback('reloadSources', (Map<String, Object?> params) async {
+    vmService.registerServiceCallback(kReloadSourcesServiceName, (Map<String, Object?> params) async {
       final String isolateId = _validateRpcStringParam('reloadSources', params, 'isolateId');
       final bool force = _validateRpcBoolParam('reloadSources', params, 'force');
       final bool pause = _validateRpcBoolParam('reloadSources', params, 'pause');
@@ -209,11 +220,11 @@ Future<vm_service.VmService> setUpVmService({
         },
       };
     });
-    registrationRequests.add(vmService.registerService('reloadSources', 'Flutter Tools'));
+    registrationRequests.add(vmService.registerService(kReloadSourcesServiceName, kFlutterToolAlias));
   }
 
   if (restart != null) {
-    vmService.registerServiceCallback('hotRestart', (Map<String, Object?> params) async {
+    vmService.registerServiceCallback(kHotRestartServiceName, (Map<String, Object?> params) async {
       final bool pause = _validateRpcBoolParam('compileExpression', params, 'pause');
       await restart(pause: pause);
       return <String, Object>{
@@ -222,10 +233,10 @@ Future<vm_service.VmService> setUpVmService({
         },
       };
     });
-    registrationRequests.add(vmService.registerService('hotRestart', 'Flutter Tools'));
+    registrationRequests.add(vmService.registerService(kHotRestartServiceName, kFlutterToolAlias));
   }
 
-  vmService.registerServiceCallback('flutterVersion', (Map<String, Object?> params) async {
+  vmService.registerServiceCallback(kFlutterVersionServiceName, (Map<String, Object?> params) async {
     final FlutterVersion version = context.get<FlutterVersion>() ?? FlutterVersion();
     final Map<String, Object> versionJson = version.toJson();
     versionJson['frameworkRevisionShort'] = version.frameworkRevisionShort;
@@ -237,10 +248,10 @@ Future<vm_service.VmService> setUpVmService({
       },
     };
   });
-  registrationRequests.add(vmService.registerService('flutterVersion', 'Flutter Tools'));
+  registrationRequests.add(vmService.registerService(kFlutterVersionServiceName, kFlutterToolAlias));
 
   if (compileExpression != null) {
-    vmService.registerServiceCallback('compileExpression', (Map<String, Object?> params) async {
+    vmService.registerServiceCallback(kCompileExpressionServiceName, (Map<String, Object?> params) async {
       final String isolateId = _validateRpcStringParam('compileExpression', params, 'isolateId');
       final String expression = _validateRpcStringParam('compileExpression', params, 'expression');
       final List<String> definitions = List<String>.from(params['definitions']! as List<Object?>);
@@ -257,10 +268,10 @@ Future<vm_service.VmService> setUpVmService({
         'result': <String, String>{'kernelBytes': kernelBytesBase64},
       };
     });
-    registrationRequests.add(vmService.registerService('compileExpression', 'Flutter Tools'));
+    registrationRequests.add(vmService.registerService(kCompileExpressionServiceName, kFlutterToolAlias));
   }
   if (device != null) {
-    vmService.registerServiceCallback('flutterMemoryInfo', (Map<String, Object?> params) async {
+    vmService.registerServiceCallback(kFlutterMemoryInfoServiceName, (Map<String, Object?> params) async {
       final MemoryInfo result = await device.queryMemoryInfo();
       return <String, Object>{
         'result': <String, Object>{
@@ -269,10 +280,10 @@ Future<vm_service.VmService> setUpVmService({
         },
       };
     });
-    registrationRequests.add(vmService.registerService('flutterMemoryInfo', 'Flutter Tools'));
+    registrationRequests.add(vmService.registerService(kFlutterMemoryInfoServiceName, kFlutterToolAlias));
   }
   if (skSLMethod != null) {
-    vmService.registerServiceCallback('flutterGetSkSL', (Map<String, Object?> params) async {
+    vmService.registerServiceCallback(kFlutterGetSkSLServiceName, (Map<String, Object?> params) async {
       final String? filename = await skSLMethod();
       if (filename == null) {
         return <String, Object>{
@@ -288,11 +299,11 @@ Future<vm_service.VmService> setUpVmService({
         },
       };
     });
-    registrationRequests.add(vmService.registerService('flutterGetSkSL', 'Flutter Tools'));
+    registrationRequests.add(vmService.registerService(kFlutterGetSkSLServiceName, kFlutterToolAlias));
   }
 
   if (flutterProject != null) {
-    vmService.registerServiceCallback('flutterGetIOSBuildOptions', (Map<String, Object?> params) async {
+    vmService.registerServiceCallback(kFlutterGetIOSBuildOptionsServiceName, (Map<String, Object?> params) async {
       final XcodeProjectInfo? info = await flutterProject.ios.projectInfo();
       if (info == null) {
         return <String, Object>{
@@ -311,7 +322,20 @@ Future<vm_service.VmService> setUpVmService({
       };
     });
     registrationRequests.add(
-      vmService.registerService('flutterGetIOSBuildOptions', 'Flutter Tools'),
+      vmService.registerService(kFlutterGetIOSBuildOptionsServiceName, kFlutterToolAlias),
+    );
+
+    vmService.registerServiceCallback(kFlutterGetAndroidBuildVariantsServiceName, (Map<String, Object?> params) async {
+      final List<String> options = await flutterProject.android.getBuildVariants();
+      return <String, Object>{
+        'result': <String, Object>{
+          kResultType: kResultTypeSuccess,
+          'variants': options,
+        },
+      };
+    });
+    registrationRequests.add(
+      vmService.registerService(kFlutterGetAndroidBuildVariantsServiceName, kFlutterToolAlias),
     );
   }
 

packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart

@@ -446,6 +446,9 @@ class FakeAndroidSdk extends Fake implements AndroidSdk {
 
   @override
   final Directory directory;
+
+  @override
+  String? get javaHome => 'java';
 }
 
 class FakeAndroidStudio extends Fake implements AndroidStudio {

packages/flutter_tools/test/commands.shard/permeable/build_appbundle_test.dart

@@ -230,4 +230,7 @@ class FakeAndroidSdk extends Fake implements AndroidSdk {
 
   @override
   final Directory directory;
+
+  @override
+  String? get javaHome => 'java';
 }

packages/flutter_tools/test/general.shard/android/android_gradle_builder_test.dart

@@ -787,6 +787,68 @@ android {
       expect(androidApk?.id, 'com.example.foo');
     });
 
+    testUsingContext('can call custom gradle task getBuildOptions and parse the result', () async {
+      final AndroidGradleBuilder builder = AndroidGradleBuilder(
+        logger: logger,
+        processManager: processManager,
+        fileSystem: fileSystem,
+        artifacts: Artifacts.test(),
+        usage: testUsage,
+        gradleUtils: FakeGradleUtils(),
+        platform: FakePlatform(),
+      );
+      processManager.addCommand(const FakeCommand(
+        command: <String>[
+          'gradlew',
+          '-q',
+          'printBuildVariants',
+        ],
+        stdout: '''
+BuildVariant: freeDebug
+BuildVariant: paidDebug
+BuildVariant: freeRelease
+BuildVariant: paidRelease
+BuildVariant: freeProfile
+BuildVariant: paidProfile
+        ''',
+      ));
+      final List<String> actual = await builder.getBuildVariants(
+        project: FlutterProject.fromDirectoryTest(fileSystem.currentDirectory),
+      );
+      expect(actual, <String>['freeDebug', 'paidDebug', 'freeRelease', 'paidRelease', 'freeProfile', 'paidProfile']);
+    }, overrides: <Type, Generator>{
+      AndroidStudio: () => FakeAndroidStudio(),
+    });
+
+    testUsingContext('getBuildOptions returns empty list if gradle returns error', () async {
+      final AndroidGradleBuilder builder = AndroidGradleBuilder(
+        logger: logger,
+        processManager: processManager,
+        fileSystem: fileSystem,
+        artifacts: Artifacts.test(),
+        usage: testUsage,
+        gradleUtils: FakeGradleUtils(),
+        platform: FakePlatform(),
+      );
+      processManager.addCommand(const FakeCommand(
+        command: <String>[
+          'gradlew',
+          '-q',
+          'printBuildVariants',
+        ],
+        stderr: '''
+Gradle Crashed
+        ''',
+        exitCode: 1,
+      ));
+      final List<String> actual = await builder.getBuildVariants(
+        project: FlutterProject.fromDirectoryTest(fileSystem.currentDirectory),
+      );
+      expect(actual, const <String>[]);
+    }, overrides: <Type, Generator>{
+      AndroidStudio: () => FakeAndroidStudio(),
+    });
+
     testUsingContext("doesn't indicate how to consume an AAR when printHowToConsumeAar is false", () async {
       final AndroidGradleBuilder builder = AndroidGradleBuilder(
         logger: logger,

packages/flutter_tools/test/general.shard/android/android_sdk_test.dart

@@ -387,7 +387,7 @@ void main() {
         ProcessManager: () => FakeProcessManager.any(),
         OperatingSystemUtils: () => FakeOperatingSystemUtilsWithJava(),
         Platform: () => FakePlatform(environment: <String, String>{
-          'JAVA_HOME': 'java-home-path',
+          AndroidSdk.javaHomeEnvironmentVariable: 'java-home-path',
         }),
         Config: () => Config,
         AndroidStudio: () => FakeAndroidStudioWithoutJdk(),

packages/flutter_tools/test/general.shard/android/android_workflow_test.dart

@@ -553,7 +553,7 @@ Review licenses that have not been accepted (y/N)?
       androidStudio: null,
       fileSystem: fileSystem,
       logger: logger,
-      platform: FakePlatform()..environment = <String, String>{'HOME': '/home/me', 'JAVA_HOME': 'home/java'},
+      platform: FakePlatform()..environment = <String, String>{'HOME': '/home/me', AndroidSdk.javaHomeEnvironmentVariable: 'home/java'},
       processManager: processManager,
       userMessages: UserMessages(),
     ).validate();
@@ -576,7 +576,7 @@ Review licenses that have not been accepted (y/N)?
       androidStudio: null,
       fileSystem: fileSystem,
       logger: logger,
-      platform: FakePlatform()..environment = <String, String>{'HOME': '/home/me', 'JAVA_HOME': 'home/java'},
+      platform: FakePlatform()..environment = <String, String>{'HOME': '/home/me', AndroidSdk.javaHomeEnvironmentVariable: 'home/java'},
       processManager: processManager,
       userMessages: UserMessages(),
     ).validate();

packages/flutter_tools/test/general.shard/resident_runner_test.dart

@@ -589,7 +589,7 @@ void main() {
         })!.toJson(),
       ),
       const FakeVmServiceRequest(
-        method: 'reloadSources',
+        method: kReloadSourcesServiceName,
         args: <String, Object>{
           'isolateId': '1',
           'pause': false,
@@ -649,7 +649,7 @@ void main() {
         })!.toJson(),
       ),
       const FakeVmServiceRequest(
-        method: 'reloadSources',
+        method: kReloadSourcesServiceName,
         args: <String, Object>{
           'isolateId': '1',
           'pause': false,
@@ -713,7 +713,7 @@ void main() {
         })!.toJson(),
       ),
       const FakeVmServiceRequest(
-        method: 'reloadSources',
+        method: kReloadSourcesServiceName,
         args: <String, Object>{
           'isolateId': '1',
           'pause': false,
@@ -776,7 +776,7 @@ void main() {
         jsonResponse: fakeVM.toJson(),
       ),
       const FakeVmServiceRequest(
-        method: 'reloadSources',
+        method: kReloadSourcesServiceName,
         args: <String, Object>{
           'isolateId': '1',
           'pause': false,
@@ -866,7 +866,7 @@ void main() {
         jsonResponse: fakeVM.toJson(),
       ),
       const FakeVmServiceRequest(
-        method: 'reloadSources',
+        method: kReloadSourcesServiceName,
         args: <String, Object>{
           'isolateId': '1',
           'pause': false,

packages/flutter_tools/test/general.shard/resident_web_runner_test.dart

@@ -63,20 +63,24 @@ const List<VmServiceExpectation> kAttachIsolateExpectations =
     'streamId': 'Isolate',
   }),
   FakeVmServiceRequest(method: 'registerService', args: <String, Object>{
-    'service': 'reloadSources',
-    'alias': 'Flutter Tools',
+    'service': kReloadSourcesServiceName,
+    'alias': kFlutterToolAlias,
   }),
   FakeVmServiceRequest(method: 'registerService', args: <String, Object>{
-    'service': 'flutterVersion',
-    'alias': 'Flutter Tools',
+    'service': kFlutterVersionServiceName,
+    'alias': kFlutterToolAlias,
   }),
   FakeVmServiceRequest(method: 'registerService', args: <String, Object>{
-    'service': 'flutterMemoryInfo',
-    'alias': 'Flutter Tools',
+    'service': kFlutterMemoryInfoServiceName,
+    'alias': kFlutterToolAlias,
   }),
   FakeVmServiceRequest(method: 'registerService', args: <String, Object>{
-    'service': 'flutterGetIOSBuildOptions',
-    'alias': 'Flutter Tools',
+    'service': kFlutterGetIOSBuildOptionsServiceName,
+    'alias': kFlutterToolAlias,
+  }),
+  FakeVmServiceRequest(method: 'registerService', args: <String, Object>{
+    'service': kFlutterGetAndroidBuildVariantsServiceName,
+    'alias': kFlutterToolAlias,
   }),
   FakeVmServiceRequest(
     method: 'streamListen',
@@ -611,7 +615,7 @@ void main() {
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[
       ...kAttachExpectations,
       const FakeVmServiceRequest(
-          method: 'hotRestart',
+          method: kHotRestartServiceName,
           jsonResponse: <String, Object>{
             'type': 'Success',
           }),
@@ -684,7 +688,7 @@ void main() {
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[
       ...kAttachExpectations,
       const FakeVmServiceRequest(
-          method: 'hotRestart',
+          method: kHotRestartServiceName,
           jsonResponse: <String, Object>{
             'type': 'Success',
           }),
@@ -883,7 +887,7 @@ void main() {
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[
       ...kAttachExpectations,
       const FakeVmServiceRequest(
-        method: 'hotRestart',
+        method: kHotRestartServiceName,
         jsonResponse: <String, Object>{
           'type': 'Failed',
         },
@@ -910,7 +914,7 @@ void main() {
     fakeVmServiceHost = FakeVmServiceHost(requests: <VmServiceExpectation>[
       ...kAttachExpectations,
       const FakeVmServiceRequest(
-        method: 'hotRestart',
+        method: kHotRestartServiceName,
         // Failed response,
         errorCode: RPCErrorCodes.kInternalError,
       ),

packages/flutter_tools/test/general.shard/vmservice_test.dart

@@ -70,7 +70,7 @@ void main() {
       vmService: mockVMService,
     );
 
-    expect(mockVMService.services, containsPair('reloadSources', 'Flutter Tools'));
+    expect(mockVMService.services, containsPair(kReloadSourcesServiceName, kFlutterToolAlias));
   });
 
   testWithoutContext('VM Service registers flutterMemoryInfo service', () async {
@@ -82,20 +82,29 @@ void main() {
       vmService: mockVMService,
     );
 
-    expect(mockVMService.services, containsPair('flutterMemoryInfo', 'Flutter Tools'));
+    expect(mockVMService.services, containsPair(kFlutterMemoryInfoServiceName, kFlutterToolAlias));
   });
 
   testWithoutContext('VmService registers flutterGetIOSBuildOptions service', () async {
     final MockVMService mockVMService = MockVMService();
-    final FlutterProject mockedVMService = MockFlutterProject(
-      mockedIos: MockIosProject(),
+    final FlutterProject mockedFlutterProject = MockFlutterProject();
+    await setUpVmService(
+      flutterProject: mockedFlutterProject,
+      vmService: mockVMService,
     );
+
+    expect(mockVMService.services, containsPair(kFlutterGetIOSBuildOptionsServiceName, kFlutterToolAlias));
+  });
+
+  testWithoutContext('VmService registers flutterGetAndroidBuildVariants service', () async {
+    final MockVMService mockVMService = MockVMService();
+    final FlutterProject mockedFlutterProject = MockFlutterProject();
     await setUpVmService(
-      flutterProject: mockedVMService,
+      flutterProject: mockedFlutterProject,
       vmService: mockVMService,
     );
 
-    expect(mockVMService.services, containsPair('flutterGetIOSBuildOptions', 'Flutter Tools'));
+    expect(mockVMService.services, containsPair(kFlutterGetAndroidBuildVariantsServiceName, kFlutterToolAlias));
   });
 
   testWithoutContext('VM Service registers flutterGetSkSL service', () async {
@@ -105,7 +114,7 @@ void main() {
       vmService: mockVMService,
     );
 
-    expect(mockVMService.services, containsPair('flutterGetSkSL', 'Flutter Tools'));
+    expect(mockVMService.services, containsPair(kFlutterGetSkSLServiceName, kFlutterToolAlias));
   });
 
   testWithoutContext('VM Service throws tool exit on service registration failure.', () async {
@@ -144,7 +153,7 @@ void main() {
       vmService: mockVMService,
     );
 
-    expect(mockVMService.services, containsPair('flutterVersion', 'Flutter Tools'));
+    expect(mockVMService.services, containsPair(kFlutterVersionServiceName, kFlutterToolAlias));
   });
 
   testUsingContext('VM Service prints messages for connection failures', () {
@@ -287,14 +296,14 @@ void main() {
       <String>['scheme1', 'scheme2'],
       MockLogger(),
     );
-    final FlutterProject mockedVMService = MockFlutterProject(
+    final FlutterProject mockedFlutterProject = MockFlutterProject(
       mockedIos: MockIosProject(mockedInfo: expectedProjectInfo),
     );
     await setUpVmService(
-      flutterProject: mockedVMService,
+      flutterProject: mockedFlutterProject,
       vmService: vmService
     );
-    final vm_service.ServiceCallback cb = vmService.serviceCallBacks['flutterGetIOSBuildOptions']!;
+    final vm_service.ServiceCallback cb = vmService.serviceCallBacks[kFlutterGetIOSBuildOptionsServiceName]!;
 
     final Map<String, dynamic> response = await cb(<String, dynamic>{});
     final Map<String, dynamic> result = response['result']! as Map<String, dynamic>;
@@ -304,16 +313,34 @@ void main() {
     expect(result['schemes'], expectedProjectInfo.schemes);
   });
 
+  testWithoutContext('VmService forward flutterGetAndroidBuildVariants request and response correctly', () async {
+    final MockVMService vmService = MockVMService();
+    final List<String> expectedOptions = <String>['debug', 'release', 'profile'];
+    final FlutterProject mockedFlutterProject = MockFlutterProject(
+      mockedAndroid: MockAndroidProject(mockedOptions: expectedOptions),
+    );
+    await setUpVmService(
+        flutterProject: mockedFlutterProject,
+        vmService: vmService
+    );
+    final vm_service.ServiceCallback cb = vmService.serviceCallBacks[kFlutterGetAndroidBuildVariantsServiceName]!;
+
+    final Map<String, dynamic> response = await cb(<String, dynamic>{});
+    final Map<String, dynamic> result = response['result']! as Map<String, dynamic>;
+    expect(result[kResultType], kResultTypeSuccess);
+    expect(result['variants'], expectedOptions);
+  });
+
   testWithoutContext('VmService forward flutterGetIOSBuildOptions request and response correctly when no iOS project', () async {
     final MockVMService vmService = MockVMService();
-    final FlutterProject mockedVMService = MockFlutterProject(
+    final FlutterProject mockedFlutterProject = MockFlutterProject(
       mockedIos: MockIosProject(),
     );
     await setUpVmService(
-        flutterProject: mockedVMService,
+        flutterProject: mockedFlutterProject,
         vmService: vmService
     );
-    final vm_service.ServiceCallback cb = vmService.serviceCallBacks['flutterGetIOSBuildOptions']!;
+    final vm_service.ServiceCallback cb = vmService.serviceCallBacks[kFlutterGetIOSBuildOptionsServiceName]!;
 
     final Map<String, dynamic> response = await cb(<String, dynamic>{});
     final Map<String, dynamic> result = response['result']! as Map<String, dynamic>;
@@ -912,11 +939,16 @@ void main() {
 
 class MockFlutterProject extends Fake implements FlutterProject {
   MockFlutterProject({
-    required IosProject mockedIos
-  }) : ios = mockedIos;
+    IosProject? mockedIos,
+    AndroidProject? mockedAndroid,
+  }) : ios = mockedIos ?? MockIosProject(),
+       android = mockedAndroid ?? MockAndroidProject();
 
   @override
   final IosProject ios;
+
+  @override
+  final AndroidProject android;
 }
 
 class MockIosProject extends Fake implements IosProject {
@@ -928,6 +960,15 @@ class MockIosProject extends Fake implements IosProject {
   Future<XcodeProjectInfo?> projectInfo() async => mockedInfo;
 }
 
+class MockAndroidProject extends Fake implements AndroidProject {
+  MockAndroidProject({this.mockedOptions = const <String>[]});
+
+  final List<String> mockedOptions;
+
+  @override
+  Future<List<String>> getBuildVariants() async => mockedOptions;
+}
+
 class MockLogger extends Fake implements Logger { }
 
 class MockVMService extends Fake implements vm_service.VmService {

packages/flutter_tools/test/integration.shard/android_gradle_print_build_variants_test.dart

+// Copyright 2014 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 'dart:convert';
+
+import 'package:collection/collection.dart';
+import 'package:file/file.dart';
+import 'package:flutter_tools/src/android/gradle_utils.dart'
+    show getGradlewFileName;
+import 'package:flutter_tools/src/base/io.dart';
+
+import '../src/common.dart';
+import 'test_utils.dart';
+
+void main() {
+  late Directory tempDir;
+
+  setUp(() async {
+    tempDir = createResolvedTempDirectorySync('run_test.');
+  });
+
+  tearDown(() async {
+    tryToDelete(tempDir);
+  });
+
+  testWithoutContext(
+      'gradle task exists named printBuildVariants that prints build variants', () async {
+    // Create a new flutter project.
+    final String flutterBin =
+    fileSystem.path.join(getFlutterRoot(), 'bin', 'flutter');
+    ProcessResult result = await processManager.run(<String>[
+      flutterBin,
+      'create',
+      tempDir.path,
+      '--project-name=testapp',
+    ], workingDirectory: tempDir.path);
+    expect(result.exitCode, 0);
+    // Ensure that gradle files exists from templates.
+    result = await processManager.run(<String>[
+      flutterBin,
+      'build',
+      'apk',
+      '--config-only',
+    ], workingDirectory: tempDir.path);
+    expect(result.exitCode, 0);
+
+    final Directory androidApp = tempDir.childDirectory('android');
+    result = await processManager.run(<String>[
+      '.${platform.pathSeparator}${getGradlewFileName(platform)}',
+      ...getLocalEngineArguments(),
+      '-q', // quiet output.
+      'printBuildVariants',
+    ], workingDirectory: androidApp.path);
+    // Verify that gradlew has a javaVersion task.
+    expect(result.exitCode, 0);
+    // Verify the format is a number on its own line.
+    const List<String> expectedLines = <String>[
+      'BuildVariant: debug',
+      'BuildVariant: release',
+      'BuildVariant: profile',
+    ];
+    final List<String> actualLines = LineSplitter.split(result.stdout.toString()).toList();
+    expect(const ListEquality<String>().equals(actualLines, expectedLines), isTrue);
+  });
+}

packages/flutter_tools/test/src/android_common.dart

@@ -36,6 +36,9 @@ class FakeAndroidBuilder implements AndroidBuilder {
     bool deferredComponentsEnabled = false,
     bool configOnly = false,
   }) async {}
+
+  @override
+  Future<List<String>> getBuildVariants({required FlutterProject project}) async => const <String>[];
 }
 
 /// Creates a [FlutterProject] in a directory named [flutter_project]

packages/flutter_tools/test/web.shard/vm_service_web_test.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 
 import 'package:file/file.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/vmservice.dart';
 import 'package:vm_service/vm_service.dart';
 import 'package:vm_service/vm_service_io.dart';
 
@@ -96,7 +97,7 @@ Future<void> validateFlutterVersion(VmService client) async {
     client.onEvent('Service'),
       emitsThrough(predicate((Event e) {
         if (e.kind == EventKind.kServiceRegistered &&
-            e.service == 'flutterVersion') {
+            e.service == kFlutterVersionServiceName) {
           method = e.method;
           return true;
         }