}

  public void testToMultiset_empty() {
    assertThat(fluent().toMultiset()).isEmpty();
  }

  public void testToMap() {
    assertThat(fluent(1, 2, 3).toMap(Functions.toStringFunction()).entrySet())
        .containsExactly(immutableEntry(1, "1"), immutableEntry(2, "2"), immutableEntry(3, "3"))
        .inOrder();
  }

    NavigableMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertThat(map.entrySet()).isEmpty();
    assertTrue(map.isEmpty());
    assertThat(map.get("five")).isNull();
  }

  public void testToMap() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    ImmutableMap<String, Integer> map = Maps.toMap(strings, LENGTH_FUNCTION);
    assertEquals(ImmutableMap.of("one", 3, "two", 3, "three", 5), map);