Add separate driver file for performance tests (#890)

testing_app/README.md

@@ -30,7 +30,7 @@ The Flutter SDK can run unit tests and widget tests in a virtual machine, withou
 - Integration Tests:
  - Run `flutter drive --driver=integration_test/driver.dart --target=integration_test/app_test.dart`
 - Performance Tests:
- - Run `flutter drive --driver=integration_test/driver.dart --target=integration_test/perf_test.dart --profile --trace-startup`
+ - Run `flutter drive --driver=integration_test/perf_driver.dart --target=integration_test/perf_test.dart --profile --trace-startup`
  - Using a physical device and running performance tests in profile mode is recommended.
  - The `--trace-startup` option is used to avoid flushing older timeline events when the timeline gets long.
 - State Management Tests:

testing_app/integration_test/perf_driver.dart

@@ -0,0 +1,25 @@
+// Copyright 2021 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:developer';
+
+import 'package:integration_test/integration_test_driver.dart';
+
+Future<void> main() {
+ return integrationDriver(
+ responseDataCallback: (data) async {
+ // If the tests reported any data, save it to the disk.
+ if (data != null) {
+ for (var entry in data.entries) {
+ log('Writing ${entry.key} to the disk.');
+ // Default storage destination is the 'build' directory.
+ await writeResponseData(
+ entry.value as Map<String, dynamic>,
+ testOutputFilename: entry.key,
+ );
+ }
+ }
+ },
+ );
+}