assertThat(actualKeys)
        .containsExactlyElementsIn(transform(expectedEntries, Entry::getKey))
        .inOrder();
  }

  public void testEntriesSpliterator() {
    List<Entry<String, Integer>> expectedEntries =
        asList(
            immutableEntry("foo", 2),
            immutableEntry("foo", 3),
            immutableEntry("bar", 4),