public void TestGetCards() { var crdsLst = new List <Card>() { new Card() { cardType = CardType.Spade, id = "2Spade", num = 2 }, new Card() { cardType = CardType.Heart, id = "7Heart", num = 7 }, new Card() { cardType = CardType.Club, id = "8Club", num = 8 }, new Card() { cardType = CardType.Diamond, id = "5Diamond", num = 5 } }; mockICards.Setup(m => m.GetCards(It.IsAny <int>())).Returns(crdsLst); ICards crds = mockICards.Object; var lstCards = crds.GetCards(4); Assert.IsNotNull(lstCards); Assert.AreEqual(lstCards.Count, 4); }