How do I mock IQueryable<T>

Question

I am creating a repository that exposes IQueryable. What is the best way to mock this out for my unit testing?

Since I am using RhinoMocks for the rest of my mock objects, I tried to do the following:

IQueryable<MyObject> QueryObject =      MockRepository.GenerateStub<IQueryable<MyObject>>(); 

This doesn't work though so I tried doing this:

IQueryable<MyObject> QueryObject =      (new List<MyObject> { new MyObject() }).AsQueryable(); 

Is there a better way to do this, or have any other mocking frameworks built support for IQueryable in?

My repository interface looks like this:

public interface IRepository<T> where T : TableServiceEntity {     IQueryable<T> Table { get; }     void Attach(T existingItem);     void Delete(T itemToDelete);     void Insert(T newItem);     T Load(string partitionKey, string rowKey);     IEnumerable<T> Load(string partitionKey);     IEnumerable<T> Query(IQueryable<T> query);     IEnumerable<T> Last(int count);     T Last();     void Update(T item); } 

Here is the method that I want to test:

public Post LoadPost(int year, int month, int day, string slug) {     var query = from p in _blogRepository.Table                 where                      p.PartitionKey == Key.Partition(year, month, day)                      && p.Slug == slug                 select p;      var posts = _blogRepository.Query(query.Take(1));      return posts.First(); } 

Then here is the test as I have it right now that will test LoadPost.

[Fact] public void LoadWillRetrieveByPartitionKeyAndRowKeyWhenUsingUriFormat() {     Repository         .Stub(x => x.Query(Arg<IQueryable<Post>>.Is.Anything))         .Return(new List<Post> {_post});      var result = Service.LoadPost(                             _post.Year(),                             _post.Month(),                              _post.Day(),                              _post.Slug);      Assert.NotNull(result); } 

The code is taken from my AzureBlog project.

Answer 1

I usually do exactly what you ended up doing in your test. When writing my tests I assume that the .Net library classes work correctly and don't contain bugs, so I can use them in the tests. When I need a test list, collection, queryable, dictionary, etc. I just create the real thing and populate with test data. It makes the tests much more readable and quicker to write, and to be honest the risk is non-existent.