public void testConcatUnmodifiable() {
    new IteratorTester<Integer>(
        5, UNMODIFIABLE, asList(1, 2), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<Integer> newTargetIterator() {
        return Iterators.concat(
            asList(1).iterator(), Arrays.<Integer>asList().iterator(), asList(2).iterator());
      }
    }.test();
  }

  public void testConcatPartiallyAdvancedSecond() {

            ListTestSuiteBuilder.using(new DoublesAsListTailSubListGenerator())
                .named("Doubles.asList, tail subList"),
            ListTestSuiteBuilder.using(new DoublesAsListMiddleSubListGenerator())
                .named("Doubles.asList, middle subList"));

    TestSuite suite = new TestSuite();
    for (ListTestSuiteBuilder<Double> builder : builders) {
      suite.addTest(
          builder

            ListTestSuiteBuilder.using(new FloatsAsListTailSubListGenerator())
                .named("Floats.asList, tail subList"),
            ListTestSuiteBuilder.using(new FloatsAsListMiddleSubListGenerator())
                .named("Floats.asList, middle subList"));

    TestSuite suite = new TestSuite();
    for (ListTestSuiteBuilder<Float> builder : builders) {
      suite.addTest(
          builder

            ListTestSuiteBuilder.using(new FloatsAsListTailSubListGenerator())
                .named("Floats.asList, tail subList"),
            ListTestSuiteBuilder.using(new FloatsAsListMiddleSubListGenerator())
                .named("Floats.asList, middle subList"));

    TestSuite suite = new TestSuite();
    for (ListTestSuiteBuilder<Float> builder : builders) {
      suite.addTest(
          builder

            ListTestSuiteBuilder.using(new IntsAsListTailSubListGenerator())
                .named("Ints.asList, tail subList"),
            ListTestSuiteBuilder.using(new IntsAsListMiddleSubListGenerator())
                .named("Ints.asList, middle subList"));

    TestSuite suite = new TestSuite();
    for (ListTestSuiteBuilder<Integer> builder : builders) {
      suite.addTest(
          builder

      Set<Object> keys = cache.asMap().keySet();
      assertFalse(keys.remove(null));
      assertFalse(keys.remove(6));
      assertFalse(keys.remove(-6));
      assertFalse(keys.removeAll(asList(null, 0, 15, 1500)));
      assertFalse(keys.retainAll(asList(null, 0, 15, 1500)));
      checkEmpty(keys);
      checkEmpty(cache);
    }
  }

  public void testKeySet_remove() {
    for (LoadingCache<Object, Object> cache : caches()) {

    assertEquals(HashMultiset.create(asList("a", "b", "a", "c")), multiset);
  }

  public void testBuilderAddAll() {
    List<String> a = asList("a", "b");
    List<String> b = asList("c", "d");
    ImmutableMultiset<String> multiset =
        new ImmutableMultiset.Builder<String>().addAll(a).addAll(b).build();
    assertEquals(HashMultiset.create(asList("a", "b", "c", "d")), multiset);
  }

        assertNotNull(second);
        // Due to round-robin, should get different channels or same order
        assertTrue(Arrays.asList(channel1, channel2).contains(first));
        assertTrue(Arrays.asList(channel1, channel2).contains(second));
    }

    @Test
    void testLeastLoadedStrategy() {
        loadBalancer.setStrategy(LoadBalancingStrategy.LEAST_LOADED);

    assertEquals(HashMultiset.create(asList("a", "b", "a", "c")), multiset);
  }

  public void testBuilderAddAll() {
    List<String> a = asList("a", "b");
    List<String> b = asList("c", "d");
    ImmutableMultiset<String> multiset =
        new ImmutableMultiset.Builder<String>().addAll(a).addAll(b).build();
    assertEquals(HashMultiset.create(asList("a", "b", "c", "d")), multiset);
  }

    // re-order
    getAll(cache, asList(0, 1, 2));
    CacheTesting.drainRecencyQueues(cache);
    assertThat(keySet).containsExactly(3, 4, 5, 6, 7, 8, 9, 0, 1, 2);

    // evict 3, 4, 5
    getAll(cache, asList(10));
    CacheTesting.drainRecencyQueues(cache);
    assertThat(keySet).containsExactly(6, 7, 8, 9, 0, 1, 2, 10);

    // re-order
    getAll(cache, asList(6, 7, 8));