@Test
public void testIfElse() {

  Parser<Integer> parser = areChars("ab").ifelse(INTEGER, constant(0));
  assertEquals("ifelse", parser.toString());
  assertEquals((Object) 12, parser.parse("ab12", mode));
  assertEquals((Object) 0, parser.parse("", mode));
  assertParser(mode, parser, "a", 0, "a");
}