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);
        }