The method 'watchPerformance' isn't defined for the type 'IntegrationTestWidgetsFlutterBinding' - flutter

Question

I'm currently doing the integrated_test codelab on https://codelabs.developers.google.com/codelabs/flutter-app-testing/#6.
I'm on step 6 where I have to test the performance of the test_app:
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:integration_test/integration_test.dart';
import 'package:testing_app_codelab/main.dart';
import 'package:testing_app_codelab/testing_app.dart';
void main() {
group('Testing App Performance Tests', () {
final binding = IntegrationTestWidgetsFlutterBinding.ensureInitialized()
as IntegrationTestWidgetsFlutterBinding;
binding.framePolicy = LiveTestWidgetsFlutterBindingFramePolicy.fullyLive;
testWidgets('Scrolling test', (tester) async {
await tester.pumpWidget(TestingApp());
final listFinder = find.byType(ListView);
await binding.watchPerformance(() async { // error is here
await tester.fling(listFinder, Offset(0, -500), 10000);
await tester.pumpAndSettle();
await tester.fling(listFinder, Offset(0, 500), 10000);
await tester.pumpAndSettle();
}, reportKey: 'scrolling_summary');
});
});
}
I've gone through the IntegrationTestWidgetsFlutterBinding documentation and watchPerformance() is a method of it(please check: https://api.flutter.dev/flutter/package-integration_test_integration_test/IntegrationTestWidgetsFlutterBinding/watchPerformance.html).
The error I get on VS code is:
The method 'watchPerformance' isn't defined for the type 'IntegrationTestWidgetsFlutterBinding'.
Try correcting the name to the name of an existing method, or defining a method named 'watchPerformance'.
When I run the Integration test on my Android phone I get this error:
Try correcting the name to the name of an existing method, or defining a method named 'watchPerformance'.
await binding.watchPerformance(() async {

Answer 1

I got the idea to solve this problem from this post Flutter / Dart package integration_test with null safety
The problem was that integration_test dependency doesn't support null-safety.
when you check which dependencies have null safety support using this command:
dart pub outdated --mode=null-safety
The output is:
Showing dependencies that are currently not opted in to null-safety.
[✗] indicates versions without null safety support.
[✓] indicates versions opting in to null safety.
Package Name Current Upgradable Resolvable Latest
direct dependencies:
integration_test ✗0.8.1 ✗0.8.1 ✗0.8.1 ✗1.0.2+3
dev_dependencies: all support null safety.
You are already using the newest resolvable versions listed in the 'Resolvable' column.
Newer versions, listed in 'Latest', may not be mutually compatible.
This means that it's legacy and doesn't have support.
To solve this I changed the pubspec.yaml from this:
dependencies:
flutter:
sdk: flutter
# The following adds the Cupertino Icons font to your application.
# Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^1.0.2
provider: ^6.0.1
test: ^1.19.5
integration_test: ^0.8.1
dev_dependencies:
flutter_test:
sdk: flutter
Changed to this instead:
dependencies:
flutter:
sdk: flutter
# The following adds the Cupertino Icons font to your application.
# Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^1.0.2
provider: ^6.0.1
test: ^1.19.5
dev_dependencies:
integration_test:
sdk: flutter
flutter_test:
sdk: flutter
After this, I ran flutter pub get on the terminal and the error disappeared.
Now when I hover over the watchPerformance() method I get this info:
Future<void> watchPerformance(Future<void> Function() action, {String reportKey = 'performance'})
package:integration_test/integration_test.dart
Watches the [FrameTiming] during action and report it to the binding with key reportKey.
This can be used to implement performance tests previously using [traceAction] and [TimelineSummary] from [flutter_driver]

Answer 2

This is a general programming error that will occur. I will put an answer in because the error description for these is often rubbish at telling you what is going on here.
The error is telling you the function called watchPerformance on the object IntegrationTestWidgetsFlutterBinding (a var here called binding), does not exist.
Does the function use a captial W instead of lower case? Take another look at the docs and check everything is spelled correctly etc.