public async Task SetAsBaseCurrency_ChangedAndNavigatedBack() { await _rateViewModel.Init(); bool called = false; Messenger.Default.Register <BaseCurrencyChangedMessage>(this, (arg) => called = true); var navigatorMock = MockRepository.GenerateMock <INavigator>(); navigatorMock.Stub(x => x.GoBackAsync()).Return(Task.CompletedTask); SimpleIoc.Default.Register(() => navigatorMock); await _rateViewModel.SetAsBaseCurrencyCommand.ExecuteAsync(); _settingsProvider.AssertWasCalled(x => x.SetValue("baseCurrency", "PLN")); Assert.IsTrue(called); navigatorMock.AssertWasCalled(x => x.GoBackAsync()); }