public async Task TokenSystemDbService_AddCustomerDetails_ReturnsCreatedSuccess() { // Arrange var mockContainer = new Mock <Container>(); var mockCosmosClient = new Mock <CosmosClient>(); var responseMock = new Mock <ItemResponse <Customer> >(); Customer newCustomer = new Customer { FirstName = "New", Surname = "Customer", Age = 35, CustomerType = CustomerType.AccountHolder, AccountNumber = 34567, Token = new Token { ServiceType = ServiceType.Transaction } }; var existingCusotmers = new List <Customer> { new Customer { Id = "1111-11111-11", FirstName = "FirstCustoer", Surname = "SecondName", Age = 35, CustomerType = CustomerType.AccountHolder, AccountNumber = 123456, Token = new Token { ServiceType = ServiceType.Transaction, TokenNumber = 1 } } }.AsQueryable(); mockContainer.Setup(x => x.GetItemLinqQueryable <Customer>(true, null, null)) .Returns((IOrderedQueryable <Customer>)existingCusotmers); mockCosmosClient.Setup(x => x.GetContainer(It.IsAny <string>(), It.IsAny <string>())) .Returns(mockContainer.Object); // Act var serviceUnderTest = new TokenSystemDbService(mockCosmosClient.Object, It.IsAny <string>(), It.IsAny <string>()); var response = await serviceUnderTest.AddCustomerDetails(newCustomer); // Assert Assert.IsNotNull(response); Assert.AreEqual(2, response.TokenNumber); Assert.AreEqual(0, response.Counter); Assert.AreEqual(Status.InQueue, response.Status); }