@Test
public void testIsChar() {

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