@Test
public void testDescendingIteration() {

    SafeIterableMap<Integer, Boolean> map = mapOf(1, 2, 3, 4);
    int[] expected = new int[]{4, 3, 2, 1};
    int index = 0;
    for (Iterator<Entry<Integer, Boolean>> iter = map.descendingIterator(); iter.hasNext(); ) {
        assertThat(iter.next().getKey(), is(expected[index++]));
    }
    assertThat(index, is(4));
}