Moq - 为构造函数注入的对象创建模拟实例

Question

题

我想为Credentials类创建一个单元测试，它在执行Calculate()方法后验证给定凭据的密码，它等于由实现IPasswordCalculator接口的对象计算的密码。

实际上，我创建的模拟对象在调用Calculate(ICredentials)方法时返回string.Empty值，而不是Pa$$w0rd ，这将是所需的返回值。

然后...

• 如何在不必手动创建存根类的情况下实现此测试？
• 如何在mock对象上定义回调方法以始终返回Pa$$w0rd ？

提前致谢。

码

IPasswordCalculator接口

/// <summary>
///     The password calculator interface.
/// </summary>
public interface IPasswordCalculator
{
    /// <summary>
    /// Calculates the user password using 
    /// <paramref name="credentials"/> instance.
    /// </summary>
    /// <param name="credentials">
    /// <see cref="ICredentials"/> to perform the calculation.
    /// </param>
    void Calculate(ICredentials credentials);
}

ICredentials界面

/// <summary>
///     The Credentials interface.
/// </summary>
public interface ICredentials
{
    /// <summary>
    ///     Gets or sets the user password.
    /// </summary>
    string Password { get; set; }

    /// <summary>
    ///     Gets the user name.
    /// </summary>
    string Username { get; }

    /// <summary>
    ///     Calculates the password.
    /// </summary>
    void Calculate();
}

凭证实施

/// <summary>
///     User credentials.
/// </summary>
public sealed class Credentials : ICredentials
{
    /// <summary>
    ///     Initializes a new instance of the <see cref="Credentials" /> class.
    /// </summary>
    /// <param name="passwordCalculator">
    ///     The credentials calculator.
    /// </param>
    /// <param name="username">
    ///     The user name.
    /// </param>
    public Credentials(IPasswordCalculator passwordCalculator, string username)
    {
        this.Calculator = passwordCalculator;
        this.Username = username;
        this.Password = string.Empty;
    }

    /// <summary>
    ///     Calculates the password.
    /// </summary>
    public void Calculate()
    {
        if (null != this.Calculator)
        {
            this.Calculator.Calculate(this);
        }
    }
}

测试

    /// <summary>
    /// Calculate should set password value expected using calculator.
    /// </summary>
    [TestMethod]
    public void CalculateShouldSetPasswordValueExpectedUsingCalculator()
    {
        ICredentials credentials = null;
        var repo = new MockRepository(MockBehavior.Default);
        var mock = repo.Create<IPasswordCalculator>();
        mock.Setup(x => x.Calculate(credentials))
            .Callback(() => { credentials.Password = "Pa$$w0rd"; });

        IPasswordCalculator calculator = mock.Object;

        credentials = new Credentials(calculator, "Me");
        credentials.Calculate();

        Assert.AreEqual("Pa$$w0rd", credentials.Password);  // Fail
    }

Answer 1

您需要以下列方式设置模拟

mock.Setup(x => x.Calculate(It.IsAny<ICredentials>()))
    .Callback((ICredentials c) => { c.Password = "Pa$$w0rd"; });

因此，您告诉它“无论您获得什么ICredentials作为Calculate方法的参数，将其Password设置为'Pa $$ word'”

Answer 2

我想你需要在调用mock.Setup（）之前初始化credentials变量。 使用您的代码，Moq需要一个调用凭证.Calculate（null）。