public void BeginUserTimeline_ForAnonymousUser_ReturnsAtLeastOneTweet() { var wasCalled = false; var twitterClient = Substitute.For<IBaseTwitterClient>(); twitterClient.SetReponseBasedOnRequestPath(); var statuses = new Statuses(twitterClient); // assert GenericResponseDelegate endUserTimeline = (a, b, c) => { wasCalled = true; var tweets = c as IEnumerable<Tweet>; Assert.That(tweets.Count(), Is.GreaterThan(0)); }; // act statuses.BeginUserTimeline("someone", endUserTimeline); Assert.That(wasCalled, Errors.CallbackDidNotFire); }