[tool] Validate gradle compileSdk

script/tool/lib/src/gradle_check_command.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:collection/collection.dart';
 import 'package:file/file.dart';
 import 'package:meta/meta.dart';
 import 'package:pub_semver/pub_semver.dart';
@@ -127,6 +128,9 @@ class GradleCheckCommand extends PackageLoopingCommand {
     if (!_validateGradleDrivenLintConfig(package, lines)) {
       succeeded = false;
     }
+    if (!_validateCompileSdkUsage(package, lines)) {
+      succeeded = false;
+    }
     return succeeded;
   }
 
@@ -415,6 +419,47 @@ for more details.''';
     return true;
   }
 
+  bool _validateCompileSdkUsage(
+      RepositoryPackage package, List<String> gradleLines) {
+    final RegExp linePattern = RegExp(r'^\s*compileSdk');
+    final RegExp legacySettingPattern = RegExp(r'^\s*compileSdkVersion');
+    final String? compileSdkLine = gradleLines
+        .firstWhereOrNull((String line) => linePattern.hasMatch(line));
+    if (compileSdkLine == null) {
+      printError('${indentation}No compileSdk or compileSdkVersion found.');
+      return false;
+    }
+    if (legacySettingPattern.hasMatch(compileSdkLine)) {
+      printError('${indentation}Please replace the deprecated '
+          '"compileSdkVersion" setting with the newer "compileSdk"');
+      return false;
+    }
+    if (compileSdkLine.contains('flutter.compileSdkVersion')) {
+      final Pubspec pubspec = package.parsePubspec();
+      final VersionConstraint? flutterConstraint =
+          pubspec.environment['flutter'];
+      final Version? minFlutterVersion =
+          flutterConstraint != null && flutterConstraint is VersionRange
+              ? flutterConstraint.min
+              : null;
+      if (minFlutterVersion == null) {
+        printError('${indentation}Unable to find a Flutter SDK version '
+            'constraint. Use of flutter.compileSdkVersion requires a minimum '
+            'Flutter version of 3.27');
+        return false;
+      }
+      if (minFlutterVersion < Version(3, 27, 0)) {
+        printError('${indentation}Use of flutter.compileSdkVersion requires a '
+            'minimum Flutter version of 3.27, but this package currently '
+            'supports $minFlutterVersion.\n'
+            "${indentation}Please update the package's minimum Flutter SDK "
+            'version to at least 3.27.');
+        return false;
+      }
+    }
+    return true;
+  }
+
   /// Validates whether the given [example]'s gradle content is configured to
   /// build its plugin target with javac lints enabled and treated as errors,
   /// if the enclosing package is a plugin.

script/tool/test/gradle_check_command_test.dart

@@ -43,6 +43,8 @@ void main() {
     bool includeNamespace = true,
     bool commentNamespace = false,
     bool warningsConfigured = true,
+    bool useDeprecatedCompileSdkVersion = false,
+    String compileSdk = '33',
   }) {
     final File buildGradle = package
         .platformDirectory(FlutterPlatform.android)
@@ -88,7 +90,7 @@ apply plugin: 'com.android.library'
 ${includeLanguageVersion ? javaSection : ''}
 android {
 ${includeNamespace ? namespace : ''}
-    compileSdk 33
+    ${useDeprecatedCompileSdkVersion ? 'compileSdkVersion' : 'compileSdk'} $compileSdk
 
     defaultConfig {
         minSdkVersion 30
@@ -989,4 +991,111 @@ dependencies {
       );
     });
   });
+
+  group('compileSdk check', () {
+    test('passes if set to a number', () async {
+      const String packageName = 'a_package';
+      final RepositoryPackage package =
+          createFakePackage(packageName, packagesDir, isFlutter: true);
+      writeFakePluginBuildGradle(package,
+          includeLanguageVersion: true, compileSdk: '35');
+      writeFakeManifest(package);
+      final RepositoryPackage example = package.getExamples().first;
+      writeFakeExampleBuildGradles(example, pluginName: packageName);
+      writeFakeManifest(example, isApp: true);
+
+      final List<String> output =
+          await runCapturingPrint(runner, <String>['gradle-check']);
+
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Validating android/build.gradle'),
+        ]),
+      );
+    });
+
+    test('passes if set to flutter.compileSdkVersion with Flutter 3.27+',
+        () async {
+      const String packageName = 'a_package';
+      final RepositoryPackage package = createFakePackage(
+          packageName, packagesDir,
+          isFlutter: true, flutterConstraint: '>=3.27.0');
+      writeFakePluginBuildGradle(package,
+          includeLanguageVersion: true,
+          compileSdk: 'flutter.compileSdkVersion');
+      writeFakeManifest(package);
+      final RepositoryPackage example = package.getExamples().first;
+      writeFakeExampleBuildGradles(example, pluginName: packageName);
+      writeFakeManifest(example, isApp: true);
+
+      final List<String> output =
+          await runCapturingPrint(runner, <String>['gradle-check']);
+
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Validating android/build.gradle'),
+        ]),
+      );
+    });
+
+    test('fails if set to flutter.compileSdkVersion with Flutter <3.27',
+        () async {
+      const String packageName = 'a_package';
+      final RepositoryPackage package = createFakePackage(
+          packageName, packagesDir,
+          isFlutter: true, flutterConstraint: '>=3.24.0');
+      writeFakePluginBuildGradle(package,
+          includeLanguageVersion: true,
+          compileSdk: 'flutter.compileSdkVersion');
+      writeFakeManifest(package);
+      final RepositoryPackage example = package.getExamples().first;
+      writeFakeExampleBuildGradles(example, pluginName: packageName);
+      writeFakeManifest(example, isApp: true);
+
+      Error? commandError;
+      final List<String> output = await runCapturingPrint(
+          runner, <String>['gradle-check'], errorHandler: (Error e) {
+        commandError = e;
+      });
+
+      expect(commandError, isA<ToolExit>());
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Use of flutter.compileSdkVersion requires a minimum '
+              'Flutter version of 3.27, but this package currently supports '
+              '3.24.0'),
+        ]),
+      );
+    });
+
+    test('fails if uses the legacy key', () async {
+      const String packageName = 'a_package';
+      final RepositoryPackage package =
+          createFakePackage(packageName, packagesDir, isFlutter: true);
+      writeFakePluginBuildGradle(package,
+          includeLanguageVersion: true, useDeprecatedCompileSdkVersion: true);
+      writeFakeManifest(package);
+      final RepositoryPackage example = package.getExamples().first;
+      writeFakeExampleBuildGradles(example, pluginName: packageName);
+      writeFakeManifest(example, isApp: true);
+
+      Error? commandError;
+      final List<String> output = await runCapturingPrint(
+          runner, <String>['gradle-check'], errorHandler: (Error e) {
+        commandError = e;
+      });
+
+      expect(commandError, isA<ToolExit>());
+      expect(
+        output,
+        containsAllInOrder(<Matcher>[
+          contains('Please replace the deprecated "compileSdkVersion" setting '
+              'with the newer "compileSdk"'),
+        ]),
+      );
+    });
+  });
 }