ConstraintServices { String getArgumentName(ConstraintViolation cv) { return "arg"+cv.getIndex(); }  ConstraintViolation[] extractViolations(ConstraintViolationException cve);  }
@Test public void testGetArgumentName() { System.out.println("getArgumentName"); ConstraintViolation cv = new ConstraintViolation(); cv.setIndex(1); String expResult = "arg1"; String result = instance.getArgumentName(cv); assertThat(result).isEqualTo(expResult); }