Fix Gold flake from gsutil fallback (#50149)

packages/flutter/lib/src/animation/animation_controller.dart

@@ -341,7 +341,8 @@ class AnimationController extends Animation<double>
   /// Stops the animation controller and sets the current value of the
   /// animation.
   ///
-  /// The new value is clamped to the range set by [lowerBound] and [upperBound].
+  /// The new value is clamped to the range set by [lowerBound] and
+  /// [upperBound].
   ///
   /// Value listeners are notified even if this does not change the value.
   /// Status listeners are notified if the animation was previously playing.

packages/flutter_goldens/lib/flutter_goldens.dart

@@ -136,17 +136,31 @@ abstract class FlutterGoldenFileComparator extends GoldenFileComparator {
   /// maintain thread safety while using the `goldctl` tool.
   @protected
   @visibleForTesting
-  static Directory getBaseDirectory(LocalFileComparator defaultComparator, Platform platform, {String suffix = ''}) {
+  static Directory getBaseDirectory(
+    LocalFileComparator defaultComparator,
+    Platform platform, {
+    String suffix = '',
+    bool local = false,
+  }) {
     const FileSystem fs = LocalFileSystem();
     final Directory flutterRoot = fs.directory(platform.environment[_kFlutterRootKey]);
-    final Directory comparisonRoot = flutterRoot.childDirectory(
-      fs.path.join(
-        'bin',
-        'cache',
-        'pkg',
-        'skia_goldens$suffix',
-      )
-    );
+    Directory comparisonRoot;
+
+    if (!local) {
+      comparisonRoot = fs.systemTempDirectory.childDirectory(
+        'skia_goldens$suffix'
+      );
+    } else {
+      comparisonRoot = flutterRoot.childDirectory(
+        fs.path.join(
+          'bin',
+          'cache',
+          'pkg',
+          'skia_goldens',
+        )
+      );
+    }
+
     final Directory testDirectory = fs.directory(defaultComparator.basedir);
     final String testDirectoryRelativePath = fs.path.relative(
       testDirectory.path,
@@ -550,6 +564,7 @@ class FlutterLocalFileComparator extends FlutterGoldenFileComparator with LocalC
     baseDirectory ??= FlutterGoldenFileComparator.getBaseDirectory(
       defaultComparator,
       platform,
+      local: true,
     );
 
     if(!baseDirectory.existsSync()) {

packages/flutter_goldens/test/flutter_goldens_test.dart

@@ -68,8 +68,9 @@ void main() {
     });
 
     test('auth performs minimal work if already authorized', () async {
-      fs.file('/workDirectory/temp/auth_opt.json')
+      final File authFile = fs.file('/workDirectory/temp/auth_opt.json')
         ..createSync(recursive: true);
+      authFile.writeAsStringSync(authTemplate());
       when(process.run(any))
         .thenAnswer((_) => Future<ProcessResult>
         .value(ProcessResult(123, 0, '', '')));
@@ -81,6 +82,16 @@ void main() {
       ));
     });
 
+    test('gsutil is checked when authorization file is present', () async {
+      final File authFile = fs.file('/workDirectory/temp/auth_opt.json')
+        ..createSync(recursive: true);
+      authFile.writeAsStringSync(authTemplate(gsutil: true));
+      expect(
+        await skiaClient.clientIsAuthorized(),
+        isFalse,
+      );
+    });
+
     test('throws for error state from auth', () async {
       platform = FakePlatform(
         environment: <String, String>{
@@ -110,7 +121,7 @@ void main() {
       );
     });
 
-    test(' throws for error state from init', () {
+    test('throws for error state from init', () {
       platform = FakePlatform(
         environment: <String, String>{
           'FLUTTER_ROOT': _kFlutterRoot,
@@ -458,7 +469,7 @@ void main() {
       );
     });
 
-    test('calculates the basedir correctly from defaultComparator', () async {
+    test('calculates the basedir correctly from defaultComparator for local testing', () async {
       final MockLocalFileComparator defaultComparator = MockLocalFileComparator();
       final Directory flutterRoot = fs.directory(platform.environment['FLUTTER_ROOT'])
         ..createSync(recursive: true);
@@ -467,6 +478,7 @@ void main() {
       final Directory basedir = FlutterGoldenFileComparator.getBaseDirectory(
         defaultComparator,
         platform,
+        local: true,
       );
       expect(
         basedir.uri,

packages/flutter_goldens/test/json_templates.dart

@@ -2,6 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+/// JSON template for the contents of the auth_opt.json file created by goldctl.
+String authTemplate({
+  bool gsutil = false,
+}) {
+  return '''
+    {
+      "Luci":false,
+      "ServiceAccount":"${gsutil ? '' : '/packages/flutter/test/widgets/serviceAccount.json'}",
+      "GSUtil":$gsutil
+    }
+  ''';
+}
+
 /// JSON response template for Skia Gold expectations request:
 /// https://flutter-gold.skia.org/json/expectations/commit/HEAD
 String rawExpectationsTemplate() {

packages/flutter_goldens_client/lib/skia_client.dart

@@ -98,7 +98,7 @@ class SkiaGoldClient {
   /// will only be called once for each instance of
   /// [FlutterSkiaGoldFileComparator].
   Future<void> auth() async {
-    if (_clientIsAuthorized())
+    if (await clientIsAuthorized())
       return;
 
     if (_serviceAccount.isEmpty) {
@@ -604,12 +604,18 @@ class SkiaGoldClient {
 
   /// Returns a boolean value to prevent the client from re-authorizing itself
   /// for multiple tests.
-  bool _clientIsAuthorized() {
+  Future<bool> clientIsAuthorized() async {
     final File authFile = workDirectory?.childFile(fs.path.join(
       'temp',
       'auth_opt.json',
     ));
-    return authFile.existsSync();
+
+    if(await authFile.exists()) {
+      final String contents = await authFile.readAsString();
+      final Map<String, dynamic> decoded = json.decode(contents) as Map<String, dynamic>;
+      return !(decoded['GSUtil'] as bool);
+    }
+    return false;
   }
 }