public async Task Handle_CustomerExist_AddIndividualCustomerPhone(
            [Frozen] Mock <IRepository <Entities.IndividualCustomer> > customerRepoMock,
            AddIndividualCustomerPhoneCommandHandler sut,
            AddIndividualCustomerPhoneCommand command,
            Entities.Person person
            )
        {
            //Act
            customerRepoMock.Setup(_ =>
                                   _.GetBySpecAsync(
                                       It.IsAny <GetIndividualCustomerSpecification>(),
                                       It.IsAny <CancellationToken>()
                                       )
                                   )
            .ReturnsAsync(new Entities.IndividualCustomer(person));

            var result = await sut.Handle(command, CancellationToken.None);

            //Assert
            result.Should().NotBeNull();
            customerRepoMock.Verify(x => x.UpdateAsync(
                                        It.IsAny <Entities.IndividualCustomer>(),
                                        It.IsAny <CancellationToken>()
                                        ));
        }
        public void Handle_CustomerDoesNotExist_ThrowArgumentNullException(
            [Frozen] Mock <IRepository <Entities.IndividualCustomer> > customerRepoMock,
            AddIndividualCustomerPhoneCommandHandler sut,
            AddIndividualCustomerPhoneCommand command
            )
        {
            // Arrange
            customerRepoMock.Setup(x => x.GetBySpecAsync(
                                       It.IsAny <GetIndividualCustomerSpecification>(),
                                       It.IsAny <CancellationToken>()
                                       ))
            .ReturnsAsync((Entities.IndividualCustomer)null);

            //Act
            Func <Task> func = async() => await sut.Handle(command, CancellationToken.None);

            //Assert
            func.Should().Throw <ArgumentNullException>()
            .WithMessage("Value cannot be null. (Parameter 'individualCustomer')");
        }