Impractical use of doCallRealMethod() when object being spy

Oh no! Another mistake in this morning. Although the code sound true but the code doesn't sound logic. Take a look at the code snippet from previous note as an example:

public class FileClass {
 public void funcB() {
  
  try {
   throw new ClassNotFoundException();
  }
  catch( ClassNotFoundException e ) {
   ...
  }
 }
}

Due to the misunderstanding between mock and spy, the following test code isn’t really practical because ClassFile is already in spy mode, the use of doCallRealMethod() is just a waste, thus invoking the real instance is more than enough. doCallRealMethod() is usable if and only if FileClass is a mock.

 @Test(expected=ClassNotFoundException.class)
 public void testFuncB() throws ClassNotFoundException {
  FileClass fc = Mockito.spy(new FileClass());
  Mockito.doCallRealMethod().when(fc).funcB();
  fc.funcB();
 }