context doesn't match when testing Provider - flutter

Question

I have written a test to check that a provider works as expected, however i get the following exception when checking that the context matches the providers context:
══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following TestFailure object was thrown running a test:
Expected:
_InheritedProvderElement<AuthScreen>:<ChangeNotifierProvider<AuthScreen>-[GlobalKey#11403](value:
Instance of 'AuthScreen', listening to value)>
Actual:
_DefaultInheritedProviderScopeElement<AuthScreen>:<_DefaultInheritedProviderScope<AuthScreen>(value:
Instance of 'AuthScreen', listening to value)>
When the exception was thrown, this was the stack:
#4 main.<anonymous closure> (file:///home/hannes/Documents/StudioProjects/brf/test/Authentication/authenticate_test.dart:24:5)
<asynchronous suspension>
#5 testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test/src/widget_tester.dart:140:29)
<asynchronous suspension>
#6 TestWidgetsFlutterBinding._runTestBody (package:flutter_test/src/binding.dart:699:19)
<asynchronous suspension>
#9 TestWidgetsFlutterBinding._runTest (package:flutter_test/src/binding.dart:679:14)
#10 AutomatedTestWidgetsFlutterBinding.runTest.<anonymous closure> (package:flutter_test/src/binding.dart:1079:24)
#16 AutomatedTestWidgetsFlutterBinding.runTest (package:flutter_test/src/binding.dart:1076:15)
#17 testWidgets.<anonymous closure> (package:flutter_test/src/widget_tester.dart:133:24)
#18 Declarer.test.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/declarer.dart:171:27)
<asynchronous suspension>
#19 Invoker.waitForOutstandingCallbacks.<anonymous closure> (package:test_api/src/backend/invoker.dart:242:15)
#24 Invoker.waitForOutstandingCallbacks (package:test_api/src/backend/invoker.dart:239:5)
#25 Declarer.test.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/declarer.dart:169:33)
#30 Declarer.test.<anonymous closure> (package:test_api/src/backend/declarer.dart:168:13)
#31 Invoker._onRun.<anonymous closure>.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:test_api/src/backend/invoker.dart:392:25)
#45 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:398:19)
#46 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:429:5)
#47 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
(elided 28 frames from class _FakeAsync, package dart:async, package dart:async-patch, and package stack_trace)
This was caught by the test expectation on the following line:
file:///home/hannes/Documents/StudioProjects/brf/test/Authentication/authenticate_test.dart line 24
The test description was:
AuthScreen provider changes value
════════════════════════════════════════════════════════════════════════════════════════════════════
Also, _childKey.currentContext is null. I don't know if that is related or if it's something else that I'm doing wrong.
I have tried to follow this guide, and my test looks like this:
import 'package:brf/models/auth_screen.dart';
import 'package:brf/screens/authenticate/authenticate.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
void main() {
setUp(() {
AuthScreen();
});
testWidgets('AuthScreen provider changes value', (WidgetTester tester) async {
final _providerKey = GlobalKey();
final _childKey = GlobalKey();
BuildContext context;
await tester.pumpWidget(
MaterialApp(
home: ChangeNotifierProvider<AuthScreen>(
key: _providerKey,
create: (c) {
context = c;
return AuthScreen();
},
child: Authenticate(key: _childKey),
),
),
);
expect(context, equals(_providerKey.currentContext));
expect(Provider.of<AuthScreen>(_childKey.currentContext).showSignIn, true);
Provider.of<AuthScreen>(context, listen: false).switchScreen();
await Future.microtask(tester.pump);
expect(Provider.of<AuthScreen>(_childKey.currentContext).showSignIn, false);
});
}
And finally AuthScreen looks like this:
import 'package:flutter/material.dart';
class AuthScreen extends ChangeNotifier{
bool _showSignIn = true;
bool get showSignIn => _showSignIn;
void switchScreen(){
_showSignIn = !_showSignIn;
notifyListeners();
}
}

Answer 1

This is the error for the null context you passed
you this one:
Builder(builder: (context) => Widget here
Try like this where you want to pass the context:
MaterialApp(
home: Builder(builder: (context) => ChangeNotifierProvider<AuthScreen>(
key: _providerKey,
create: (c) {
context = c;
return AuthScreen();
},
child: Authenticate(key: _childKey),
),
),
);