使用Moq提供正数

Question

我正在尝试使用Moq中的It类提供正数：

It.Is<int>(a => a > 0)

但是结果始终等于0。实现此目标的正确方法是什么？

Answer 1

听起来您的测试有点低级，应该测试代码的逻辑，该代码根据接收到的值而不是值本身执行操作。话虽如此，这里有些代码可能会有所帮助。它包装了内置的.NET随机数生成器，以确保输出已知的数字序列。

[TestMethod]
public void VerifyMultipleValues()
{
    // Define values to return
    var values = new[] {5, 9, 10};

    // Create a mock of the interface
    var mockRand = new Mock<IRandomNumber>();
    // Define behaviour of the mock
    mockRand.Setup(m => m.GetRand(It.IsAny<int>())).ReturnsInOrder(values);
    // Point the factory output at the mock object
    DomainFactory.RandomNumber = mockRand.Object;

    // Create an instance of the wrapper object
    // The wrapper calls the factory which in turn calls the mock object that was just created
    // to return known values
    var wrapper = new Wrapper();
    foreach (var v in values)
    {
        var output = wrapper.GetNumber(100);
        Assert.AreEqual(v, output);
    }

    // Clean up
    DomainFactory.RandomNumber = null;
}

ReturnsInOrder是源自here的扩展方法。

public static void ReturnsInOrder<T, TResult>(this ISetup<T, TResult> setup,
  params TResult[] results) where T : class
{
    setup.Returns(new Queue<TResult>(results).Dequeue);
}

其余代码如下：

// Interface
public interface IRandomNumber
{
    int GetRand(int end);
}

// Implementation
public class RandomNumber : IRandomNumber
{
    private static readonly Random _random = new Random();

    public int GetRand(int end)
    {
        return _random.Next(0, end);
    }   
}

// Factory
public static class DomainFactory
{
    private static IRandomNumber _randomNumber;
    public static IRandomNumber RandomNumber
    {
        get { return _randomNumber ?? (_randomNumber = new RandomNumber()); }
        set { _randomNumber = value; }
    }
}

// Wrapper
public class Wrapper
{
    public int GetNumber(int parameter)
    {
        return DomainFactory.RandomNumber.GetRand(parameter);
    }
}