public void Verify_exception_of_multiple_map()
 {
     sut.Addalias(new TestId(2), "Alias2");
     try
     {
         sut.Addalias(new TestId(3), "Alias2");
         Assert.Fail("Expect exception for invalid alias");
     }
     catch (Exception ex)
     {
         Assert.That(ex.Message, Contains.Substring("Alias alias2 already mapped to Test_2"));
     }
 }