1     public interface ICalculator
2     {
3       int Add(int a, int b);
4       string Mode { get; set; }
5     }

1     [TestMethod]
2     public void Test_SettingReturnValue_ReturnsValueWithSpecifiedArguments()
3     {
4       var calculator = Substitute.For<ICalculator>();
5       calculator.Add(1, 2).Returns(3);
6       Assert.AreEqual(calculator.Add(1, 2), 3);
7     }

 1     [TestMethod]
 2     public void Test_SettingReturnValue_ReturnsDefaultValueWithDifferentArguments()
 3     {
 4       var calculator = Substitute.For<ICalculator>();
 5 
 6       // 设置调用返回值为3
 7       calculator.Add(1, 2).Returns(3);
 8 
 9       Assert.AreEqual(calculator.Add(1, 2), 3);
10       Assert.AreEqual(calculator.Add(1, 2), 3);
11 
12       // 当使用不同参数调用时,返回值不是3
13       Assert.AreNotEqual(calculator.Add(3, 6), 3);
14     }

 1     [TestMethod]
 2     public void Test_SettingReturnValue_ReturnsValueFromProperty()
 3     {
 4       var calculator = Substitute.For<ICalculator>();
 5 
 6       calculator.Mode.Returns("DEC");
 7       Assert.AreEqual(calculator.Mode, "DEC");
 8 
 9       calculator.Mode = "HEX";
10       Assert.AreEqual(calculator.Mode, "HEX");
11     }