public void IsValid_GetValidationResult_ReturnsValidationObjectWhenValueIsNotAnEmailAddress(object value)
        {
            // Arrange
            ValidationContext             validationContext             = new ValidationContext(new { }, null, null);
            ValidateEmailAddressAttribute validateEmailAddressAttribute = new ValidateEmailAddressAttribute(nameof(DummyStrings.Dummy), typeof(DummyStrings));

            // Act
            // IsValid is a protected function, the public function GetValidationResult calls it.
            ValidationResult validationResult = validateEmailAddressAttribute.GetValidationResult(value, validationContext);

            // Assert
            Assert.Equal(DummyStrings.Dummy, validationResult.ErrorMessage);
        }
        public void IsValid_GetValidationResult_ReturnsNullWhenValueIsAnEmailAddressOrNullOrAnEmptyString(object value)
        {
            // Arrange
            ValidationContext             validationContext             = new ValidationContext(new { }, null, null);
            ValidateEmailAddressAttribute validateEmailAddressAttribute = new ValidateEmailAddressAttribute(nameof(DummyStrings.Dummy), typeof(DummyStrings));

            // Act
            // IsValid is a protected function, the public function GetValidationResult calls it.
            ValidationResult validationResult = validateEmailAddressAttribute.GetValidationResult(value, validationContext);

            // Assert
            Assert.Null(validationResult);
        }