// Check that the iterator iterates the correct number of times
 private void checkSizes(String msg, int sz, Iterator it, int expectedSize) {
   assertEquals(msg, expectedSize, sz);
   int result = 0;
   while (it.hasNext()) {
     result++;
     it.next();
   }
   assertEquals(msg, expectedSize, result);
 }
  public void testIteration() {
    assertTrue(_nbhm.isEmpty());
    assertThat(_nbhm.put("k1", "v1"), nullValue());
    assertThat(_nbhm.put("k2", "v2"), nullValue());

    String str1 = "";
    for (Iterator<Map.Entry<String, String>> i = _nbhm.entrySet().iterator(); i.hasNext(); ) {
      Map.Entry<String, String> e = i.next();
      str1 += e.getKey();
    }
    assertThat("found all entries", str1, anyOf(is("k1k2"), is("k2k1")));

    String str2 = "";
    for (Iterator<String> i = _nbhm.keySet().iterator(); i.hasNext(); ) {
      String key = i.next();
      str2 += key;
    }
    assertThat("found all keys", str2, anyOf(is("k1k2"), is("k2k1")));

    String str3 = "";
    for (Iterator<String> i = _nbhm.values().iterator(); i.hasNext(); ) {
      String val = i.next();
      str3 += val;
    }
    assertThat("found all vals", str3, anyOf(is("v1v2"), is("v2v1")));

    assertThat(
        "toString works", _nbhm.toString(), anyOf(is("{k1=v1, k2=v2}"), is("{k2=v2, k1=v1}")));
  }
  // ---
  public void testNonBlockingIdentityHashMapIteratorMultithreaded()
      throws InterruptedException, ExecutionException {
    TestKeyFeeder feeder = getTestKeyFeeder();
    final int itemCount = feeder.size();

    // validate results
    final NonBlockingIdentityHashMap<Long, TestKey> items = feeder.getMapMultithreaded();
    assertEquals("size()", itemCount, items.size());

    assertEquals("values().size()", itemCount, items.values().size());

    assertEquals("entrySet().size()", itemCount, items.entrySet().size());

    int iteratorCount = 0;
    for (TestKey m : items.values()) iteratorCount++;
    // sometimes a different result comes back the second time
    int iteratorCount2 = 0;
    for (Iterator<TestKey> it = items.values().iterator(); it.hasNext(); ) {
      iteratorCount2++;
      it.next();
    }
    assertEquals("iterator counts differ", iteratorCount, iteratorCount2);
    assertEquals("values().iterator() count", itemCount, iteratorCount);
  }