1     public interface ICalculator
 2     {
 3       int Add(int a, int b);
 4       string Mode { get; set; }
 5     }
 6 
 7     [TestMethod]
 8     public void Test_ReturnForAnyArgs_ReturnForAnyArgs()
 9     {
10       var calculator = Substitute.For<ICalculator>();
11 
12       calculator.Add(1, 2).ReturnsForAnyArgs(100);
13       Assert.AreEqual(calculator.Add(1, 2), 100);
14       Assert.AreEqual(calculator.Add(-7, 15), 100);
15     }