Fall-back to platform tools in Android SDK detection logic. (#28863)

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

@@ -365,6 +365,14 @@ class AndroidSdk {
   }
 
   static bool validSdkDirectory(String dir) {
+    return sdkDirectoryHasLicneses(dir) || sdkDirectoryHasPlatformTools(dir);
+  }
+
+  static bool sdkDirectoryHasPlatformTools(String dir) {
+    return fs.isDirectorySync(fs.path.join(dir, 'platform-tools'));
+  }
+
+  static bool sdkDirectoryHasLicneses(String dir) {
     return fs.isDirectorySync(fs.path.join(dir, 'licenses'));
   }
 

packages/flutter_tools/lib/src/application_package.dart

@@ -14,6 +14,7 @@ import 'base/context.dart';
 import 'base/file_system.dart';
 import 'base/os.dart' show os;
 import 'base/process.dart';
+import 'base/user_messages.dart';
 import 'build_info.dart';
 import 'globals.dart';
 import 'ios/ios_workflow.dart';
@@ -94,7 +95,7 @@ class AndroidApk extends ApplicationPackage {
   factory AndroidApk.fromApk(File apk) {
     final String aaptPath = androidSdk?.latestVersion?.aaptPath;
     if (aaptPath == null) {
-      printError('Unable to locate the Android SDK; please run \'flutter doctor\'.');
+      printError(userMessages.aaptNotFound);
       return null;
     }
 

packages/flutter_tools/lib/src/base/user_messages.dart

@@ -115,6 +115,8 @@ class UserMessages {
   String get androidStudioResetDir =>
       'Consider removing your android-studio-dir setting by running:\n'
       'flutter config --android-studio-dir=';
+  String get aaptNotFound =>
+      'Could not locate aapt. Please ensure you have the Android buildtools installed.';
 
   // Messages used in NoAndroidStudioValidator
   String androidStudioMissing(String location) =>

packages/flutter_tools/test/application_package_test.dart

@@ -65,6 +65,34 @@ void main() {
       ).path)..createSync(recursive: true);
     });
 
+    testUsingContext('Licenses not available, platform and buildtools available, apk exists', () async {
+      const String aaptPath = 'aaptPath';
+      final File apkFile = fs.file('app.apk');
+      final AndroidSdkVersion sdkVersion = MockitoAndroidSdkVersion();
+      when(sdkVersion.aaptPath).thenReturn(aaptPath);
+      when(sdk.latestVersion).thenReturn(sdkVersion);
+      when(sdk.platformToolsAvailable).thenReturn(true);
+      when(sdk.licensesAvailable).thenReturn(false);
+      when(mockProcessManager.runSync(
+          argThat(equals(<String>[
+            aaptPath,
+            'dump',
+            'xmltree',
+            apkFile.path,
+            'AndroidManifest.xml',
+          ])),
+          workingDirectory: anyNamed('workingDirectory'),
+          environment: anyNamed('environment'),
+        ),
+      ).thenReturn(ProcessResult(0, 0, _aaptDataWithDefaultEnabledAndMainLauncherActivity, null));
+
+      final ApplicationPackage applicationPackage = await ApplicationPackageFactory.instance.getPackageForPlatform(
+        TargetPlatform.android_arm,
+        applicationBinary: apkFile,
+      );
+      expect(applicationPackage.name, 'app.apk');
+    }, overrides: overrides);
+
     testUsingContext('Licenses available, build tools not, apk exists', () async {
       when(sdk.latestVersion).thenReturn(null);
       final FlutterProject project = await FlutterProject.current();