用Moq实现IQueryable的模拟类 [英] Mocking classes that implement IQueryable with Moq

问题描述

我花了一个晚上试图模拟实现IQueryable的对象:

I spent an evening trying to mock an object that implements IQueryable:

public interface IRepo<T> : IQueryable<T>
{
}

我能想到的最好的方法是这样的:

The best I could come up with is something like this:

var items = new Item[] {}.AsQueryable();

var repo = new Mock<IRepo>();
repo.Setup(r => r.GetEnumerator()).Returns(items.GetEnumerator());
repo.Setup(r => r.Provider).Returns(items.Provider);
repo.Setup(r => r.ElementType).Returns(items.ElementType);
repo.Setup(r => r.Expression).Returns(items.Expression);

有没有更简洁的方法可以做到这一点?在IRepo中公开返回IQueryable的属性/方法和像这样的简单模拟会更容易:

Is there a more concise way to do the same? It would be easier to expose a property/method in IRepo that returns IQueryable and the simply mock like this:

repo.Setup(r => r.GetItems()).Returns(new Items[]{ }.AsQueryable());

但这不是我想做的=)

推荐答案

这并不是什么新鲜事物，只是一种更清洁的方式.我也有一些存储库，其中存储库本身也是一个IQueryable，所以我需要同样的东西.我基本上只是将您的代码放在我的测试项目的根目录级别的扩展方法中，以使其可用于所有测试:

This is nothing new, just a cleaner way of doing it. I also have repositories where the repository itself is also an IQueryable, so I needed the same thing. I basically just put your code into an extension method like this at the root level of my test project, to make it available to all tests:

public static class MockExtensions
{
    public static void SetupIQueryable<T>(this Mock<T> mock, IQueryable queryable)
        where T: class, IQueryable
    {
        mock.Setup(r => r.GetEnumerator()).Returns(queryable.GetEnumerator());
        mock.Setup(r => r.Provider).Returns(queryable.Provider);
        mock.Setup(r => r.ElementType).Returns(queryable.ElementType);
        mock.Setup(r => r.Expression).Returns(queryable.Expression);
    }
}

这基本上只是提供了可重用性，因为您可能想在多个测试中进行此操作，并且在每个测试中它都可以使意图清晰且使混乱最小化. :)

This basically just offers reusability, since you're likely to want to do this in several tests, and in each test it makes the intention clear and the mess minimal. :)

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