Object of(Object component) {
    return of(component, LOG);
  }
@Test
  public void should_log_warning_if_toString_is_not_overridden() {
    Logger log = mock(Logger.class);
    keys.of(new Object(), log);
    verifyNoInteractions(log);

    // only on non-first runs, to avoid false-positives on singletons
    keys.of(new Object(), log);
    verify(log).warn(startsWith("Bad component key"));
  }