@Test
 public void should_return_negative_one_if_keyword_not_found() {
   assertThat(DEFAULT_EQUAL.indexOf(TRUE), equalTo(-1));
 }
 @Test
 public void should_return_index_of_keyword_as_substring() {
   assertThat(
       DEFAULT_EQUAL.indexOf(EQUAL), equalTo(DEFAULT_EQUAL.toString().indexOf(EQUAL.toString())));
 }