Mocking classes that implement IQueryable with Moq

Question

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

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

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); 

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()); 

But this is not what I want to do =)

Answer 1

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);     } } 

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. :)