C#开发中如何编写可测试的代码

public interface IEmailService
{
    void SendEmail(string to, string subject, string body);
}

public class EmailService : IEmailService
{
    public void SendEmail(string to, string subject, string body)
    {
        // 发送电子邮件的实现逻辑
    }
}

public class MyClass
{
    private readonly IEmailService _emailService;

    public MyClass(IEmailService emailService)
    {
        _emailService = emailService;
    }

    public void DoSomething()
    {
        // 使用_emailService进行操作
    }
}

// 在单元测试中使用测试替身
[TestClass]
public class MyClassTests
{
    [TestMethod]
    public void DoSomething_ShouldSendEmail()
    {
        var emailServiceMock = new Mock<IEmailService>();
        var myClass = new MyClass(emailServiceMock.Object);

        myClass.DoSomething();

        emailServiceMock.Verify(e => e.SendEmail(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>()), Times.Once);
    }
}

public class Calculator
{
    public int Add(int a, int b)
    {
        return a + b;
    }

    public int Divide(int a, int b)
    {
        if (b == 0)
        {
            throw new DivideByZeroException();
        }

        return a / b;
    }
}

// 单元测试
[TestClass]
public class CalculatorTests
{
    [TestMethod]
    public void Add_ShouldReturnSum()
    {
        var calculator = new Calculator();

        var result = calculator.Add(2, 3);

        Assert.AreEqual(5, result);
    }

    [TestMethod]
    public void Divide_ShouldThrowDivideByZeroException()
    {
        var calculator = new Calculator();

        Assert.ThrowsException<DivideByZeroException>(() => calculator.Divide(5, 0));
    }
}