Mocking LINQ DataContext

[Test]
[VerifyMocks]
public void Valid_username_and_password_return_OK()
{
    var fake = new[] { new Data.User() };
    using (var r = new RecordExpectations())
    {
        var db = new InsightDataContext();
        var users = db.Users.Where(u => u.Username == "foo" && u.PasswordHash == null);
        r.Return(fake);
    }

    var session = new Session { Username = "foo" };
    session.Put();
}