@Test
public void testNotChar() {

  Parser<Void> scanner = Scanners.notChar('a');
  assertNull(scanner.parse("b"));
  assertScanner(mode, scanner, "bcd", "cd");
  assertFailure(mode, scanner, "abc", 1, 1, "^a expected, a encountered.");
  assertFailure(mode, scanner, "", 1, 1);
}