public async Task GetCustomerReturnsCustomerUsingInvalidId() { var options = new DbContextOptionsBuilder <CustomerDbContext>() .UseInMemoryDatabase(nameof(GetCustomerReturnsCustomerUsingInvalidId)) .Options; var dbContext = new CustomerDbContext(options); //Mock Object for the mapper var customerProfile = new CustomerProfile(); var configuration = new MapperConfiguration(cfg => cfg.AddProfile(customerProfile)); var mapper = new Mapper(configuration); var customersProvider = new CustomerProvider(dbContext, null, mapper); var customer = await customersProvider.GetCustomerAsync(-1); Assert.False(customer.IsSuccess); Assert.Null(customer.Customer); Assert.NotNull(customer.ErrorMessage); }