public void Should_list_all_books() { Catalogue catalogue = new Catalogue(); catalogue.Add(new Book("1857239407", "George Lucas", "Star Wars: A New Hope", 256, 20)); catalogue.Add(new Ebook("0450011844", "Frank Herbert", "Dune", 608)); Assert.That(catalogue.GetTitles(), Is.EqualTo(new[] { "Dune", "Star Wars: A New Hope" })); }