Mock (Moq) for unit testing)

Mock is translated as "Mocking". In fact, it is to forge an object for testing. In unit testing, when the method to be tested depends on other objects, this object is generally "forged" for test simplicity:

• No need to consider the complexity of dependent objects (Convenient Preparation of test data)

• Focus only on the testing method, and do not extend the unit test to the testing dependent object.

  Commodity categories in discount algorithm test malls:
  

    public class Product {        public int ProductID { get; set; }        public string Name { get; set; }        public string Description { get; set; }        public decimal Price { get; set; }        public string Category { set; get; }    }

Discount interface:

    public interface IDiscountHelper {        decimal ApplyDiscount(decimal totalParam);    }

Discount algorithm tested

    public class LinqValueCalculator : IValueCalculator {        private IDiscountHelper discounter;        public LinqValueCalculator(IDiscountHelper discountParam) {            discounter = discountParam;        }        public decimal ValueProducts(IEnumerable<Product> products) {            return discounter.ApplyDiscount(products.Sum(p => p.Price));        }

Obviously, the method to be testedValueProductsDiscount InterfaceIDiscountHelperHere, by forging an implementationIDiscountHelperInterface object.

Moq features

1. Create forged object
   Mock<IDiscountHelper> mock = new Mock<IDiscountHelper>();
   
2. Method for setting forged objects
   mock.Setup(m => m.ApplyDiscount(It.IsAny<decimal>()))
   

3. Parameter restrictions
   t.IsAny<decimal>()PassItRestrictions:

   Limit expression	Explanation	Example
   It. Is	Test the bool value returned by Predicate	It.Is<decimal>(v => v == 0)
   It. isany	Any value of the T Type	It.IsAny()
   It. isinrange	The value of the T type parameter is within or outside the range (determined by the rangekind parameter)	It.IsInRange<int>(1, 100, Range.Inclusive)

4. Set Return Value
   .Returns<decimal>(total => total);

Construct unit test

    [TestClass]    public class UnitTest2 {        private Product[] createProduct(decimal value) {            return new[] { new Product { Price = value } };        }        [TestMethod]        [ExpectedException(typeof(System.ArgumentOutOfRangeException))]        public void Pass_Through_Variable_Discounts() {            // arrange            Mock<IDiscountHelper> mock = new Mock<IDiscountHelper>();            mock.Setup(m => m.ApplyDiscount(It.IsAny<decimal>()))                .Returns<decimal>(total => total);            mock.Setup(m => m.ApplyDiscount(It.Is<decimal>(v => v == 0)))                .Throws<System.ArgumentOutOfRangeException>();            mock.Setup(m => m.ApplyDiscount(It.Is<decimal>(v => v > 100)))                .Returns<decimal>(total => (total * 0.9M));            mock.Setup(m => m.ApplyDiscount(It.IsInRange<decimal>(10, 100,                Range.Inclusive))).Returns<decimal>(total => total - 5);            var target = new LinqValueCalculator(mock.Object);            // act            decimal FiveDollarDiscount = target.ValueProducts(createProduct(5));            decimal TenDollarDiscount = target.ValueProducts(createProduct(10));            decimal FiftyDollarDiscount = target.ValueProducts(createProduct(50));            decimal HundredDollarDiscount = target.ValueProducts(createProduct(100));            decimal FiveHundredDollarDiscount = target.ValueProducts(createProduct(500));            // assert            Assert.AreEqual(5, FiveDollarDiscount, "$5 Fail");            Assert.AreEqual(5, TenDollarDiscount, "$10 Fail");            Assert.AreEqual(45, FiftyDollarDiscount, "$50 Fail");            Assert.AreEqual(95, HundredDollarDiscount, "$100 Fail");            Assert.AreEqual(450, FiveHundredDollarDiscount, "$500 Fail");            target.ValueProducts(createProduct(0));        }    }

Mock (Moq) for unit testing)