public void readCustomerByIdWithoutResultTest() { Mock <ITSegClientesRepository> mock = new Mock <ITSegClientesRepository>(); mock.Setup(x => x.ReadTSegClienteById(It.IsAny <long>())).Returns(getTSegClienteNull()); CustomerDomainService test = new CustomerDomainService(mock.Object); var response = test.ReadCustomerById(100); Assert.IsTrue(response == null); }