@Test
public void testAtomic() {

  assertEquals("integer", INTEGER.atomic().toString());
  assertEquals((Object) 'b', areChars("ab").atomic().parse("ab", mode));
  assertEquals((Object) 'a',
      Parsers.or(areChars("ab").atomic(), isChar('a')).parse("a", mode));
  assertFailure(mode, areChars("ab").atomic(), "a", 1, 2);
}