public void TestAddTopping() { var pizza = new Pizza() { Name = "TestName" }; var topping = new Topping() { Name = "TestToppingName" }; var testPizzaEntity = new PizzaEntity() { Name = "TestName", Toppings = new List <ToppingEntity>() }; pizzaRepositoryMock.Setup(m => m.GetByName("TestName")) .Returns(testPizzaEntity); toppingServiceMock.Setup(m => m.GetByName("TestToppingName")) .Returns(topping); var result = sut.AddToppings(pizza, new List <Topping>() { topping }); Assert.AreEqual(1, result.Toppings.Count); }