### Question:
InstantiatorErrors { static Errors noSuchField(Errors errors, String fieldName) { return errors.addMessage( "no such field %s", fieldName); }    }### Answer:
@Test public void addinTwiceTheSameMessageDoesNotDuplicateTheError() { check( "no such field a", noSuchField(noSuchField(new Errors(), "a"), "a")); }