@Test
public void testPrefix() {

  expect(unaryOp.apply(1)).andReturn(-1);
  expect(unaryOp.apply(-1)).andReturn(1);
  expect(unaryOp.apply(1)).andReturn(-1);
  replay();
  Parser<Integer> parser = INTEGER.prefix(isChar('-').retn(unaryOp));
  assertEquals(Integer.valueOf(-1), parser.parse("---1", mode));
}