@Test
public void testNewest() {

    SafeIterableMap<Integer, Boolean> map = mapOf();
    assertThat(map.newest(), nullValue());
    map.putIfAbsent(1, false);
    assertThat(map.newest().getKey(), is(1));
    map.putIfAbsent(2, false);
    assertThat(map.newest().getKey(), is(2));
    map.remove(2);
    assertThat(map.eldest().getKey(), is(1));
    map.remove(1);
    assertThat(map.newest(), nullValue());
}