.addEquivalenceGroup(ImmutableList.of("b"))
        .addEquivalenceGroup(ImmutableList.of("a", "b"), ImmutableList.of("a", "b"))
        .test();
  }

  public void testPairwiseEquivalent_equals() {
    new EqualsTester()
        .addEqualityGroup(Equivalence.equals().pairwise(), Equivalence.equals().pairwise())
        .addEqualityGroup(Equivalence.identity().pairwise())
        .testEquals();
  }