使用NUnit的.net TDD工作流最佳实践

更新:我对这篇文章做了重大修改，详细信息请查看修订历史。

我开始深入研究TDD与NUnit，尽管我很喜欢检查我在stackoverflow找到的一些资源，我经常发现自己没有得到很好的吸引力。

所以我真正想要实现的是获得某种清单/工作流程——这就是我需要你们帮助的地方——或者"测试计划"，它将给我提供体面的代码覆盖率。

那么让我们假设一个理想的场景，我们可以从头开始一个项目，比如说一个Mailer助手类，它将具有以下代码:

(我创建这个类只是为了用一个代码示例帮助解决问题，所以任何批评或建议都是鼓励的，我们将非常欢迎)

Mailer.cs

using System.Net.Mail;
using System;
namespace Dotnet.Samples.NUnit
{
    public class Mailer
    {
        readonly string from;
        public string From { get { return from; } }
        readonly string to;
        public string To { get { return to; } }
        readonly string subject;
        public string Subject { get { return subject; } }
        readonly string cc;
        public string Cc { get { return cc; } }
        readonly string bcc;
        public string BCc { get { return bcc; } }
        readonly string body;
        public string Body { get { return body; } }
        readonly string smtpHost;
        public string SmtpHost { get { return smtpHost; } }
        readonly string attachment;
        public string Attachment { get { return Attachment; } }
        public Mailer(string from = null, string to = null, string body = null, string subject = null, string cc = null, string bcc = null, string smtpHost = "localhost", string attachment = null)
        {
            this.from = from;
            this.to = to;
            this.subject = subject;
            this.body = body;
            this.cc = cc;
            this.bcc = bcc;
            this.smtpHost = smtpHost;
            this.attachment = attachment;
        }
        public void SendMail()
        {
            if (string.IsNullOrEmpty(From))
                throw new ArgumentNullException("Sender e-mail address cannot be null or empty.", from);
            SmtpClient smtp = new SmtpClient();
            MailMessage mail = new MailMessage();
            smtp.Send(mail);
        }
    }
}

MailerTests.cs

using System;
using NUnit.Framework;
using FluentAssertions;
namespace Dotnet.Samples.NUnit
{
    [TestFixture]
    public class MailerTests
    {
        [Test, Ignore("No longer needed as the required code to pass has been already implemented.")]
        public void SendMail_FromArgumentIsNotNullOrEmpty_ReturnsTrue()
        {
            // Arrange
            dynamic argument = null;
            // Act
            Mailer mailer = new Mailer(from: argument);
            // Assert
            Assert.IsNotNullOrEmpty(mailer.From, "Parameter cannot be null or empty.");
        }
        [Test]
        public void SendMail_FromArgumentIsNullOrEmpty_ThrowsException()
        {
            // Arrange
            dynamic argument = null;
            Mailer mailer = new Mailer(from: argument);
            // Act
            Action act = () => mailer.SendMail();
            act.ShouldThrow<ArgumentNullException>();
            // Assert
            Assert.Throws<ArgumentNullException>(new TestDelegate(act));
        }
        [Test]
        public void SendMail_FromArgumentIsOfTypeString_ReturnsTrue()
        {
            // Arrange
            dynamic argument = String.Empty;
            // Act
            Mailer mailer = new Mailer(from: argument);
            // Assert
            mailer.From.Should().Be(argument, "Parameter should be of type string.");
        }
        // INFO: At this first 'iteration' I've almost covered the first argument of the method so logically this sample is nowhere near completed.
        // TODO: Create a test that will eventually require the implementation of a method to validate a well-formed email address.
        // TODO: Create as much tests as needed to give the remaining parameters good code coverage.
    }
}

因此，在我的前两个失败的测试之后，下一个明显的步骤将是实现功能，使它们通过，但是，我应该保留失败的测试，并在实现代码后创建新的测试，使它们通过，还是我应该修改现有的测试，使它们通过?

关于这个话题的任何建议都将非常感谢。