assertThat(nullsArePassed.reverse().convert("foo")).isEqualTo("backward");
    assertThat(nullsArePassed.reverse().convert(null)).isEqualTo("backward");
  }

  public void testNullIsNotPassedThrough() {
    Converter<String, String> nullsAreHandled = sillyConverter(true);
    assertThat(nullsAreHandled.convert("foo")).isEqualTo("forward");
    assertThat(nullsAreHandled.convert(null)).isNull();