@Test
public void regexGroup_noMatch() {

  assertThat(first(Pattern.compile("(.*)x"), 1).in("bar")).isEmpty();
  assertThat(first(Pattern.compile("(.*x)"), 1).in("bar")).isEmpty();
  assertThat(first(Pattern.compile(".*(x)"), 1).in("bar")).isEmpty();
  assertThat(first(Pattern.compile("(.*x)"), 1).in("")).isEmpty();
  assertThat(first(Pattern.compile("(.*x)"), 1).iterateIn("")).isEmpty();
}