public void AddCDTest() { int oldDictSize = data.cds.Count; CD cd = new CD() { id = 1234, title = "Nevermind", group = "Nirvana" }; dataRepository.AddCD(cd); int newDictSize = data.cds.Count; //check if size of new and old dictionary is different Assert.AreNotEqual(oldDictSize, newDictSize); //check if dictionary contains object Assert.IsTrue(data.cds.ContainsKey(1234)); Assert.IsTrue(data.cds.ContainsValue(cd)); }