public void CanRefreshAddToExistingTweetsCollection()
        {
            // setup twitter api mock return values
            Statuses statuses = new Statuses();

            statuses.Add(new Status {
                Id = "000", CreatedAt = DateTime.Today
            });
            statuses.Add(new Status {
                Id = "111", CreatedAt = DateTime.Today.AddDays(-2)
            });
            statuses.Add(new Status {
                Id = "222", CreatedAt = DateTime.Today.AddDays(-4)
            });

            // add some tweets to tweet manager
            _tweetsManager.All.Add(new Status {
                Id = "888", CreatedAt = DateTime.Today.AddDays(-10)
            });
            _tweetsManager.All.Add(new Status {
                Id = "999", CreatedAt = DateTime.Today.AddDays(-12)
            });

            // record
            Expect.Call(_twitterApiClient.FriendsTimelineSince("888")).Return(statuses);

            // playback
            _mocks.ReplayAll();
            _tweetsManager.Refresh();

            // assert
            Assert.AreEqual(5, _tweetsManager.All.Count);
            Assert.AreEqual("000", _tweetsManager.All[0].Id);
            Assert.AreEqual("111", _tweetsManager.All[1].Id);
            Assert.AreEqual("222", _tweetsManager.All[2].Id);
            Assert.AreEqual("888", _tweetsManager.All[3].Id);
            Assert.AreEqual("999", _tweetsManager.All[4].Id);
            _mocks.VerifyAll();
        }