@Test
public void group() {

    assertNull("asdf : a -> null", Str.group("asdf", "a"));
    assertNull("asdf : q -> null", Str.group("asdf", "q"));
    assertEquals("asdf : (s) -> s", Str.group("asdf", "(s)"), "s");
    assertEquals("asdf : ^.(..) -> sd", Str.group("asdf", "^.(..)"), "sd");
    assertNull("asdf : ^.{5}(.+) -> null", Str.group("asdf", "^.{5}(.+)"));
}