public void it_should_maintain_a_unique_list_of_created_tags() { RandomNumberGenerator randomNumberGenerator = new SystemRandomNumberGenerator(); TagFactory tagFactory = new TagFactory(randomNumberGenerator); tagFactory.GetTagByName("Test Tag"); tagFactory.GetTagByName("Test Tag 2"); tagFactory.GetTagByName("Test Tag"); List <Tag> tags = tagFactory.GetAllTags(); Assert.AreEqual(2, tags.Count); Assert.AreEqual(new Tag("Test Tag"), tags[0]); Assert.AreEqual(new Tag("Test Tag 2"), tags[1]); }