@Test
public void testFloorKey() {

    IncrementalSortMap<Integer, String> q = map5();
    Object e1 = q.floorKey(three);
    assertEquals(three, e1);
    Object e2 = q.floorKey(six);
    assertEquals(five, e2);
    Object e3 = q.floorKey(one);
    assertEquals(one, e3);
    Object e4 = q.floorKey(zero);
    assertNull(e4);
}