assertThat(addImpliedFeatures(newHashSet(IMPLIES_IMPLIES_FOO_AND_IMPLIES_BAR)))
        .containsExactly(IMPLIES_IMPLIES_FOO_AND_IMPLIES_BAR, IMPLIES_FOO, FOO, IMPLIES_BAR, BAR);
  }

  public void testImpliedFeatures_returnsNewSetInstance() {
    Set<Feature<?>> features = newHashSet(IMPLIES_FOO);
    assertThat(impliedFeatures(features)).isNotSameInstanceAs(features);
  }

  public void testImpliedFeatures_returnsImpliedFeatures() {