刚接触asp.NET中的TDD,我的写作测试是否正确?

在过去的几个月里,我读了很多关于TDD的文章,决定跳进去用一个简单的例子来尝试一下,我只是不确定我在实践中是否测试了正确的东西。下面是用于验证电子邮件的自定义数据注释的测试:

using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace MembershipTest.Tests
{
    [TestClass]
    public class CustomDataAnnotationsTest
    {
        [TestMethod]
        public void CustomDataAnnotations_Email_ReturnTrueIfNull()
        {
            // Arrange
            EmailAttribute attribute = new EmailAttribute();

            // Act
            bool result = attribute.IsValid(null);

            // Assert
            Assert.AreEqual(true, result);
        }

        [TestMethod]
        public void CustomDataAnnotations_Email_ReturnFalseIfInvalid()
        {
            // Arrange
            EmailAttribute attribute = new EmailAttribute();

            // Act
            bool result = attribute.IsValid("()[]\\;:,<>@example.com");

            // Assert
            Assert.AreEqual(false, result);
        }

        [TestMethod]
        public void CustomDataAnnotations_Email_ReturnTrueIfValid()
        {
            // Arrange
            EmailAttribute attribute = new EmailAttribute();

            // Act
            bool result = attribute.IsValid("john.smith@example.com");

            // Assert
            Assert.AreEqual(true, result);
        }
    }
}

下面是为测试编写的后续代码:

using System;
using System.ComponentModel.DataAnnotations;
using System.Net.Mail;

public class EmailAttribute : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        //Let RequiredAttribute validate whether the value is required or not.
        if (value == null)
        {
            return true;
        }

        //Check to see if System.Net.Mail can send to the address.
        try
        {
            var i = new MailAddress(value.ToString());
        }
        catch (Exception)
        {
            return false;
        }

        return true;
    }

}