public void WhenCustomerIsNull_ThenArgumentNullExceptionIsThrown()
        {
            var validator = new CustomerTDD.CustomerValidator();

            Action action = () => validator.Validate(null);

            action.Should().Throw <ArgumentNullException>();
        }
        public void WhenCustomerHasAgeLessThan18_ThenValidationFails()
        {
            var validator = new CustomerTDD.CustomerValidator();
            var customer  = new CustomerTDD.CustomerMock(expectedAge: 16);

            bool validate = validator.Validate(customer);

            validate.Should().BeFalse();
        }
        public void WhenCustomerHasAgeGreaterThanOrEqualTo18_ThenValidationPasses(int expectedAge)
        {
            var validator = new CustomerTDD.CustomerValidator();
            var customer  = new CustomerTDD.CustomerMock(expectedAge: expectedAge);

            bool validate = validator.Validate(customer);

            validate.Should().BeTrue();
        }