How to properly fake IQueryable<T> from Repository using Moq?

Question

I have a class that takes an IRepository in its constructor like this ...

    public class UserService
    {
       public IRepository<User> _repo { get; set; }
       public UserService(IRepository<User> repo = null)
       {
        _repo = repo ?? new UserRepository();
       }

and has a method that looks like this ...

public bool IsUserActive(email string)
{
   //The method actually does more but to keep it simple lets imagine 
   // it does this
   User user = _repo.Find(u => u.Email == email).First();
   return user.IsActive;
}

The IRepository looks like this.

public interface IRepository<T> : IDisposable where T : IEntity
{
    void InsertOrUpdate(T entity);
    void Delete(T entity);
    IQueryable<T> Find(Func<T, bool> query);
    T Find(int id);
    void Save();
}

I would like to test the IsUserActive method and make sure it returns false if the IsActive field of the user is false, and vice versa.

I'm trying the following ...

    [Test]
    public void IsUserActive_EmailThatWillReturnInactiveUser_ReturnsFalse()
    {
        //Arrange
        var fakeUserRepo = new Mock<IRepository<User>>();
        var query = new Func<User, bool>(u => u.Email == "AnyString");
        var listOfMatchingUsers = new List<User>() 
        {
                    new User 
                    { 
                        Email = "AnyString", 
                        IsActive = False 
                    }
        };
        IQueryable<User> queryableUsers = listOfMatchingUsers.AsQueryable();
        fakeUserRepo.Setup(r => r.Find(query)).Returns(queryableUsers);
        var userService = new UserService(fakeUserRepo.Object);

        //Act
        var result = userService.IsUserActive("AnyString");

        //Assert
        Assert.IsFalse(result);
    }

When I run in NUnit I get the Error "Sequence Contains No Elements" on this line

var result = userService.IsUserActive("AnyString");

Where am I going wrong?

Answer 1

Change mock setup to

fakeUserRepo.Setup(r => r.Find(It.IsAny<Func<User, bool>>()))
            .Returns(queryableUsers);