build aar prints how to consume the artifacts (#44127)

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

@@ -545,6 +545,45 @@ Future<void> buildGradleAar({
     '$successMark Built ${fs.path.relative(repoDirectory.path)}.',
     color: TerminalColor.green,
   );
+  _printHowToConsumeAar(
+    buildMode: androidBuildInfo.buildInfo.modeName,
+    androidPackage: project.manifest.androidPackage,
+    repoPath: repoDirectory.path,
+  );
+}
+
+/// Prints how to consume the AAR from a host app.
+void _printHowToConsumeAar({
+  @required String buildMode,
+  @required String androidPackage,
+  @required String repoPath,
+}) {
+  assert(buildMode != null);
+  assert(androidPackage != null);
+  assert(repoPath != null);
+
+  printStatus('''
+
+${terminal.bolden('Consuming the Module')}
+  1. Open ${fs.path.join('<host>', 'app', 'build.gradle')}
+  2. Ensure you have the repositories configured, otherwise add them:
+
+      repositories {
+        maven {
+            url '$repoPath'
+        }
+        maven {
+            url 'http://download.flutter.io'
+        }
+      }
+
+  3. Make the host app depend on the $buildMode module:
+
+      dependencies {
+        ${buildMode}Implementation '$androidPackage:flutter_$buildMode:1.0'
+      }
+
+To learn more, visit https://flutter.dev/go/build-aar''');
 }
 
 String _hex(List<int> bytes) {

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

@@ -1501,56 +1501,115 @@ plugin2=${plugin2.path}
       ProcessManager: () => mockProcessManager,
     });
 
+    testUsingContext('indicates how to consume an AAR', () async {
+      final File manifestFile = fs.file('pubspec.yaml');
+      manifestFile.createSync(recursive: true);
+      manifestFile.writeAsStringSync('''
+        flutter:
+          module:
+            androidPackage: com.example.test
+        '''
+      );
+
+      fs.file('.android/gradlew').createSync(recursive: true);
+
+      fs.file('.android/gradle.properties')
+        .writeAsStringSync('irrelevant');
+
+      fs.file('.android/build.gradle')
+        .createSync(recursive: true);
+
+      // Let any process start. Assert after.
+      when(mockProcessManager.run(
+        any,
+        environment: anyNamed('environment'),
+        workingDirectory: anyNamed('workingDirectory'),
+      )).thenAnswer((_) async => ProcessResult(1, 0, '', ''));
+
+      fs.directory('build/outputs/repo').createSync(recursive: true);
+
+      await buildGradleAar(
+        androidBuildInfo: const AndroidBuildInfo(BuildInfo(BuildMode.release, null)),
+        project: FlutterProject.current(),
+        outputDir: fs.directory('build/'),
+        target: '',
+      );
+
+      final BufferLogger logger = context.get<Logger>();
+      expect(
+        logger.statusText,
+        contains('Built build/outputs/repo'),
+      );
+      expect(
+        logger.statusText,
+        contains('''
+Consuming the Module
+  1. Open <host>/app/build.gradle
+  2. Ensure you have the repositories configured, otherwise add them:
+
+      repositories {
+        maven {
+            url 'build/outputs/repo'
+        }
+        maven {
+            url 'http://download.flutter.io'
+        }
+      }
+
+  3. Make the host app depend on the release module:
+
+      dependencies {
+        releaseImplementation 'com.example.test:flutter_release:1.0'
+      }
+
+To learn more, visit https://flutter.dev/go/build-aar'''));
+
+    }, overrides: <Type, Generator>{
+      AndroidSdk: () => mockAndroidSdk,
+      AndroidStudio: () => mockAndroidStudio,
+      Artifacts: () => mockArtifacts,
+      Cache: () => cache,
+      Platform: () => android,
+      FileSystem: () => fs,
+      ProcessManager: () => mockProcessManager,
+    });
+
     testUsingContext('build aar uses selected local engine', () async {
       when(mockArtifacts.getArtifactPath(Artifact.flutterFramework,
           platform: TargetPlatform.android_arm, mode: anyNamed('mode'))).thenReturn('engine');
       when(mockArtifacts.engineOutPath).thenReturn(fs.path.join('out', 'android_arm'));
 
-      final File manifestFile = fs.file('path/to/project/pubspec.yaml');
+      final File manifestFile = fs.file('pubspec.yaml');
       manifestFile.createSync(recursive: true);
       manifestFile.writeAsStringSync('''
-        name: test
-        version: 1.0.0+1
-        dependencies:
-          flutter:
-            sdk: flutter
         flutter:
           module:
-            androidX: false
             androidPackage: com.example.test
-            iosBundleIdentifier: com.example.test
         '''
       );
 
-      final File gradlew = fs.file('path/to/project/.android/gradlew');
+      final File gradlew = fs.file('.android/gradlew');
       gradlew.createSync(recursive: true);
 
-      fs.file('path/to/project/.android/gradle.properties')
+      fs.file('.android/gradle.properties')
         .writeAsStringSync('irrelevant');
 
-      fs.file('path/to/project/.android/build.gradle')
+      fs.file('.android/build.gradle')
         .createSync(recursive: true);
 
       when(mockProcessManager.run(
-          <String> ['/path/to/project/.android/gradlew', '-v'],
+          <String> ['.android/gradlew', '-v'],
           workingDirectory: anyNamed('workingDirectory'),
           environment: anyNamed('environment'),
-      )).thenAnswer(
-          (_) async => ProcessResult(1, 0, '5.1.1', ''),
-      );
-
-      // write schemaData otherwise pubspec.yaml file can't be loaded
-      writeEmptySchemaFile(fs);
-      fs.currentDirectory = 'path/to/project';
+      )).thenAnswer((_) async => ProcessResult(1, 0, '5.1.1', ''));
 
       // Let any process start. Assert after.
       when(mockProcessManager.run(
         any,
         environment: anyNamed('environment'),
         workingDirectory: anyNamed('workingDirectory'),
-      )).thenAnswer(
-          (_) async => ProcessResult(1, 0, '', ''),
-      );
+      )).thenAnswer((_) async => ProcessResult(1, 0, '', ''));
+
       fs.directory('build/outputs/repo').createSync(recursive: true);
 
       await buildGradleAar(
@@ -1566,7 +1625,7 @@ plugin2=${plugin2.path}
         workingDirectory: anyNamed('workingDirectory')),
       ).captured.last;
 
-      expect(actualGradlewCall, contains('/path/to/project/.android/gradlew'));
+      expect(actualGradlewCall, contains('/.android/gradlew'));
       expect(actualGradlewCall, contains('-PlocalEngineOut=out/android_arm'));
     }, overrides: <Type, Generator>{
       AndroidSdk: () => mockAndroidSdk,