A dead-simple example of how to test a riverpod provider with Mockito. What we have here is a simple class of cat that has a method sound. This class has been used via a change notifier provider. On the app, we have an elevated button that on tapping calls the sound method.
import 'package:flutter/material.dart'; import 'package:flutter_riverpod/flutter_riverpod.dart'; import 'package:flutter_test/flutter_test.dart'; import 'package:mockito/annotations.dart'; import 'package:mockito/mockito.dart'; import 'cat_test.mocks.dart'; class Cat extends ChangeNotifier { String sound() => "Meow"; } final catProvider = ChangeNotifierProvider<Cat>((ref) { return Cat(); }); // Annotation which generates the cat.mocks.dart library and the MockCat class. @GenerateMocks([Cat]) void main() { // Create mock object. var mockCat = MockCat(); when(mockCat.sound()).thenReturn('Meow'); testWidgets('Cat meows correctly', (WidgetTester tester) async { await tester.pumpWidget(ProviderScope( overrides: [ catProvider.overrideWithValue(mockCat), ], child: MaterialApp( home: Consumer(builder: (context, ref, child) { final _cat = ref.watch(catProvider); return ElevatedButton( key: Key("make_sound"), onPressed: () async { try { _cat.sound(); } catch (err) {} }, child: const Text('Make Sound'), ); }), ), )); await tester.tap(find.byKey(Key("make_sound"))); verify(mockCat.sound()).called(1); }); } 
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