[flutter_tools] Fix bundle file not found when flavor contains upperc… (#92660)

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

@@ -873,6 +873,11 @@ File findBundleFile(FlutterProject project, BuildInfo buildInfo, Logger logger,
       getBundleDirectory(project)
         .childDirectory('${buildInfo.lowerCasedFlavor}${camelCase('_${buildInfo.modeName}')}')
         .childFile('app-${buildInfo.lowerCasedFlavor}-${buildInfo.modeName}.aab'));
+
+    // The Android Gradle plugin 4.1.0 does only lowercase the first character of flavor name.
+    fileCandidates.add(getBundleDirectory(project)
+        .childDirectory('${buildInfo.uncapitalizedFlavor}${camelCase('_${buildInfo.modeName}')}')
+        .childFile('app-${buildInfo.uncapitalizedFlavor}-${buildInfo.modeName}.aab'));
   }
   for (final File bundleFile in fileCandidates) {
     if (bundleFile.existsSync()) {

packages/flutter_tools/lib/src/build_info.dart

@@ -193,10 +193,14 @@ class BuildInfo {
   String get modeName => getModeName(mode);
   String get friendlyModeName => getFriendlyModeName(mode);
 
-  /// the flavor name in the output files is lower-cased (see flutter.gradle),
+  /// the flavor name in the output apk files is lower-cased (see flutter.gradle),
   /// so the lower cased flavor name is used to compute the output file name
   String? get lowerCasedFlavor => flavor?.toLowerCase();
 
+  /// the flavor name in the output bundle files has the first character lower-cased,
+  /// so the uncapitalized flavor name is used to compute the output file name
+  String? get uncapitalizedFlavor => _uncapitalize(flavor);
+
   /// Convert to a structured string encoded structure appropriate for usage
   /// in build system [Environment.defines].
   ///
@@ -1008,3 +1012,10 @@ String getNameForHostPlatformArch(HostPlatform platform) {
       return 'x64';
   }
 }
+
+String? _uncapitalize(String? s) {
+  if (s == null || s.isEmpty) {
+    return s;
+  }
+  return s.substring(0, 1).toLowerCase() + s.substring(1);
+}

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

@@ -305,6 +305,34 @@ void main() {
     expect(bundle.path, '/build/app/outputs/bundle/foo_barDebug/app-foo_bar-debug.aab');
   });
 
+  testWithoutContext(
+      'Finds app bundle when flavor contains underscores and uppercase letters in release mode - Gradle 4.1', () {
+    final FlutterProject project = generateFakeAppBundle('foo_BarRelease', 'app-foo_Bar-release.aab', fileSystem);
+    final File bundle = findBundleFile(
+      project,
+      const BuildInfo(BuildMode.release, 'Foo_Bar', treeShakeIcons: false),
+      BufferLogger.test(),
+      TestUsage(),
+    );
+
+    expect(bundle, isNotNull);
+    expect(bundle.path, '/build/app/outputs/bundle/foo_BarRelease/app-foo_Bar-release.aab');
+  });
+
+  testWithoutContext(
+      'Finds app bundle when flavor contains underscores and uppercase letters in debug mode - Gradle 4.1', () {
+    final FlutterProject project = generateFakeAppBundle('foo_BarDebug', 'app-foo_Bar-debug.aab', fileSystem);
+    final File bundle = findBundleFile(
+      project,
+      const BuildInfo(BuildMode.debug, 'Foo_Bar', treeShakeIcons: false),
+      BufferLogger.test(),
+      TestUsage(),
+    );
+
+    expect(bundle, isNotNull);
+    expect(bundle.path, '/build/app/outputs/bundle/foo_BarDebug/app-foo_Bar-debug.aab');
+  });
+
   testWithoutContext('AAB not found', () {
     final FlutterProject project = FlutterProject.fromDirectoryTest(fileSystem.currentDirectory);
     final TestUsage testUsage = TestUsage();