public async Task GetByAccountId_ReturnTransactionViewModelTestAsync() { var transactions = TransactionMock.TransactionModelFaker.Generate(3); _accountRepositoryMock.Setup(x => x.GetTransactionsByAccountId(transactions.FirstOrDefault().AccountId)) .ReturnsAsync(transactions); _mapperMock.Setup(x => x.Map <IEnumerable <TransactionViewModel> >(It.IsAny <IEnumerable <Transaction> >())) .Returns(TransactionMock.TransactionViewModelModelFaker.Generate(3)); var accountAppService = new AccountAppService(_accountRepositoryMock.Object, _mapperMock.Object, _transactionServiceMock.Object, _domainNotificationMock.Object); var accountMethod = await accountAppService.GetByAccountId(transactions.FirstOrDefault().AccountId); var accountResult = Assert.IsAssignableFrom <IEnumerable <TransactionViewModel> >(accountMethod); Assert.NotNull(accountResult); Assert.NotEmpty(accountResult); }