public void testPollFirstEntry() {
SnapTreeMap map = map5();
Map.Entry e = map.pollFirstEntry();
assertEquals(one, e.getKey());
assertEquals("A", e.getValue());
e = map.pollFirstEntry();
assertEquals(two, e.getKey());
map.put(one, "A");
e = map.pollFirstEntry();
assertEquals(one, e.getKey());
assertEquals("A", e.getValue());