Use Gradle KTS in new Android app projects by default (flutter#154061)

This PR resolves flutter#151166

Author: bartekpacia

dev/devicelab/bin/tasks/engine_dependency_proxy_test.dart

@@ -29,14 +29,17 @@ Future<void> main() async {
     await runProjectTest((FlutterProject flutterProject) async {
       await inDirectory(path.join(flutterProject.rootPath, 'android'), () async {
         section('Insert gradle testing script');
-        final File build = File(path.join(
-          flutterProject.rootPath, 'android', 'app', 'build.gradle',
-        ));
-        build.writeAsStringSync(
+        final File buildFile = getAndroidBuildFile(path.join(flutterProject.rootPath, 'android'));
+        buildFile.writeAsStringSync(
           '''
-task printEngineMavenUrl() {
+tasks.register("printEngineMavenUrl") {
     doLast {
-        println project.repositories.find { it.name == 'maven' }.url
+        project.repositories.forEach { repo ->
+            if (repo.name == "maven") {
+                repo as MavenArtifactRepository
+                logger.quiet(repo.url.toString())
+            }
+        }
     }
 }
           ''',

dev/devicelab/lib/framework/apk_utils.dart

@@ -256,18 +256,17 @@ class FlutterProject {
   String get rootPath => path.join(parent.path, name);
   String get androidPath => path.join(rootPath, 'android');
   String get iosPath => path.join(rootPath, 'ios');
+  File get appBuildFile => getAndroidBuildFile(androidPath);
 
   Future<void> addCustomBuildType(String name, {required String initWith}) async {
-    final File buildScript = File(
-      path.join(androidPath, 'app', 'build.gradle'),
-    );
+    final File buildScript = appBuildFile;
 
     buildScript.openWrite(mode: FileMode.append).write('''
 
 android {
     buildTypes {
-        $name {
-            initWith $initWith
+        create("$name") {
+            initWith(getByName("$initWith"))
         }
     }
 }
@@ -288,14 +287,12 @@ android {
   }
 
   Future<void> setMinSdkVersion(int sdkVersion) async {
-    final File buildScript = File(
-      path.join(androidPath, 'app', 'build.gradle'),
-    );
+    final File buildScript = appBuildFile;
 
     buildScript.openWrite(mode: FileMode.append).write('''
 android {
     defaultConfig {
-        minSdkVersion $sdkVersion
+        minSdk = $sdkVersion
     }
 }
     ''');
@@ -308,22 +305,20 @@ android {
   }
 
   Future<void> addProductFlavors(Iterable<String> flavors) async {
-    final File buildScript = File(
-      path.join(androidPath, 'app', 'build.gradle'),
-    );
+    final File buildScript = appBuildFile;
 
     final String flavorConfig = flavors.map((String name) {
       return '''
-$name {
-    applicationIdSuffix ".$name"
-    versionNameSuffix "-$name"
+create("$name") {
+    applicationIdSuffix = ".$name"
+    versionNameSuffix = "-$name"
 }
       ''';
     }).join('\n');
 
     buildScript.openWrite(mode: FileMode.append).write('''
 android {
-    flavorDimensions "mode"
+    flavorDimensions.add("mode")
     productFlavors {
         $flavorConfig
     }
@@ -332,9 +327,7 @@ android {
   }
 
   Future<void> introduceError() async {
-    final File buildScript = File(
-      path.join(androidPath, 'app', 'build.gradle'),
-    );
+    final File buildScript = appBuildFile;
     await buildScript.writeAsString((await buildScript.readAsString()).replaceAll('buildTypes', 'builTypes'));
   }
 
@@ -477,3 +470,14 @@ String? validateSnapshotDependency(FlutterProject project, String expectedTarget
   return contentSnapshot.contains('$expectedTarget ')
     ? null : 'Dependency file should have $expectedTarget as target. Instead found $contentSnapshot';
 }
+
+File getAndroidBuildFile(String androidPath) {
+  final File groovyFile = File(path.join(androidPath, 'app', 'build.gradle'));
+  final File kotlinFile = File(path.join(androidPath, 'app', 'build.gradle.kts'));
+
+  if (groovyFile.existsSync()) {
+    return groovyFile;
+  }
+
+  return kotlinFile;
+}

packages/flutter_tools/lib/src/project.dart

@@ -467,7 +467,19 @@ class AndroidProject extends FlutterProjectPlatform {
   static final RegExp _androidNamespacePattern = RegExp('android {[\\S\\s]+namespace\\s*=?\\s*[\'"](.+)[\'"]');
   static final RegExp _applicationIdPattern = RegExp('^\\s*applicationId\\s*=?\\s*[\'"](.*)[\'"]\\s*\$');
   static final RegExp _imperativeKotlinPluginPattern = RegExp('^\\s*apply plugin\\:\\s+[\'"]kotlin-android[\'"]\\s*\$');
-  static final RegExp _declarativeKotlinPluginPattern = RegExp('^\\s*id\\s+[\'"]kotlin-android[\'"]\\s*\$');
+
+  /// Examples of strings that this regex matches:
+  /// - `id "kotlin-android"`
+  /// - `id("kotlin-android")`
+  /// - `id ( "kotlin-android" ) `
+  /// - `id "org.jetbrains.kotlin.android"`
+  /// - `id("org.jetbrains.kotlin.android")`
+  /// - `id ( "org.jetbrains.kotlin.android" )`
+  static final List<RegExp> _declarativeKotlinPluginPatterns = <RegExp>[
+      RegExp('^\\s*id\\s*\\(?\\s*[\'"]kotlin-android[\'"]\\s*\\)?\\s*\$'),
+      RegExp('^\\s*id\\s*\\(?\\s*[\'"]org.jetbrains.kotlin.android[\'"]\\s*\\)?\\s*\$'),
+  ];
+
 
   /// Pattern used to find the assignment of the "group" property in Gradle.
   /// Expected example: `group "dev.flutter.plugin"`
@@ -563,7 +575,9 @@ class AndroidProject extends FlutterProjectPlatform {
   /// True, if the app project is using Kotlin.
   bool get isKotlin {
     final bool imperativeMatch = firstMatchInFile(appGradleFile, _imperativeKotlinPluginPattern) != null;
-    final bool declarativeMatch = firstMatchInFile(appGradleFile, _declarativeKotlinPluginPattern) != null;
+    final bool declarativeMatch = _declarativeKotlinPluginPatterns.any((RegExp pattern) {
+      return (firstMatchInFile(appGradleFile, pattern) != null);
+    });
     return imperativeMatch || declarativeMatch;
   }
 

packages/flutter_tools/templates/app_shared/android-java.tmpl/app/build.gradle.tmpl renamed to packages/flutter_tools/templates/app_shared/android-java.tmpl/app/build.gradle.kts.tmpl

@@ -1,8 +1,8 @@
 plugins {
-    id "com.android.application"
-    id "kotlin-android"
+    id("com.android.application")
+    id("kotlin-android")
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
-    id "dev.flutter.flutter-gradle-plugin"
+    id("dev.flutter.flutter-gradle-plugin")
 }
 
 android {
@@ -16,7 +16,7 @@ android {
     }
 
     kotlinOptions {
-        jvmTarget = JavaVersion.VERSION_1_8
+        jvmTarget = JavaVersion.VERSION_1_8.toString()
     }
 
     defaultConfig {
@@ -34,7 +34,7 @@ android {
         release {
             // TODO: Add your own signing config for the release build.
             // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig = signingConfigs.debug
+            signingConfig = signingConfigs.getByName("debug")
         }
     }
 }

packages/flutter_tools/templates/app_shared/android-java.tmpl/build.gradle.kts.tmpl

@@ -0,0 +1,18 @@
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.buildDir = file("../build")
+subprojects {
+    project.buildDir = file("${rootProject.buildDir}/${project.name}")
+}
+subprojects {
+    project.evaluationDependsOn(":app")
+}
+
+tasks.register<Delete>("clean") {
+    delete(rootProject.buildDir)
+}

packages/flutter_tools/templates/app_shared/android-java.tmpl/build.gradle.tmpl

@@ -1,8 +1,8 @@
 plugins {
-    id "com.android.application"
-    id "kotlin-android"
+    id("com.android.application")
+    id("kotlin-android")
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
-    id "dev.flutter.flutter-gradle-plugin"
+    id("dev.flutter.flutter-gradle-plugin")
 }
 
 android {
@@ -16,7 +16,7 @@ android {
     }
 
     kotlinOptions {
-        jvmTarget = JavaVersion.VERSION_1_8
+        jvmTarget = JavaVersion.VERSION_1_8.toString()
     }
 
     defaultConfig {
@@ -34,7 +34,7 @@ android {
         release {
             // TODO: Add your own signing config for the release build.
             // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig = signingConfigs.debug
+            signingConfig = signingConfigs.getByName("debug")
         }
     }
 }

packages/flutter_tools/templates/app_shared/android-kotlin.tmpl/app/build.gradle.tmpl renamed to packages/flutter_tools/templates/app_shared/android-kotlin.tmpl/app/build.gradle.kts.tmpl

@@ -0,0 +1,18 @@
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.buildDir = file("../build")
+subprojects {
+    project.buildDir = file("${rootProject.buildDir}/${project.name}")
+}
+subprojects {
+    project.evaluationDependsOn(":app")
+}
+
+tasks.register<Delete>("clean") {
+    delete(rootProject.buildDir)
+}

packages/flutter_tools/templates/app_shared/android-kotlin.tmpl/build.gradle.kts.tmpl

@@ -0,0 +1,25 @@
+pluginManagement {
+    val flutterSdkPath = run {
+        val properties = java.util.Properties()
+        file("local.properties").inputStream().use { properties.load(it) }
+        val flutterSdkPath = properties.getProperty("flutter.sdk")
+        require(flutterSdkPath != null) { "flutter.sdk not set in local.properties" }
+        flutterSdkPath
+    }
+
+    includeBuild("$flutterSdkPath/packages/flutter_tools/gradle")
+
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+plugins {
+    id("dev.flutter.flutter-plugin-loader") version "1.0.0"
+    id("com.android.application") version "{{agpVersion}}" apply false
+    id("org.jetbrains.kotlin.android") version "{{kotlinVersion}}" apply false
+}
+
+include(":app")