assertTrue("containsAll(this) should return true", collection.containsAll(collection));
  }

  public void testContainsAll_partialOverlap() {
    assertFalse(
        "containsAll(partialOverlap) should return false",
        collection.containsAll(MinimalCollection.of(e0(), e3())));
  }

  public void testContainsAll_disjoint() {
    assertFalse(
        "containsAll(disjoint) should return false",