@VisibleForTesting
  List<Class<?>> findClassesToTest(
      Iterable<? extends Class<?>> classes, Iterable<String> explicitTestNames) {
    // "a.b.Foo" -> a.b.Foo.class
    TreeMap<String, Class<?>> classMap = Maps.newTreeMap();
    for (Class<?> cls : classes) {
      classMap.put(cls.getName(), cls);
    }
    // Foo.class -> [FooTest.class, FooTests.class, FooTestSuite.class, ...]

          .put(SortedMap.class, ImmutableSortedMap.of())
          .put(ImmutableSortedMap.class, ImmutableSortedMap.of())
          .put(NavigableMap.class, Maps.unmodifiableNavigableMap(Maps.newTreeMap()))
          .put(Multimap.class, ImmutableMultimap.of())
          .put(ImmutableMultimap.class, ImmutableMultimap.of())
          .put(ListMultimap.class, ImmutableListMultimap.of())

          .put(SortedMap.class, ImmutableSortedMap.of())
          .put(ImmutableSortedMap.class, ImmutableSortedMap.of())
          .put(NavigableMap.class, Maps.unmodifiableNavigableMap(Maps.newTreeMap()))
          .put(Multimap.class, ImmutableMultimap.of())
          .put(ImmutableMultimap.class, ImmutableMultimap.of())
          .put(ListMultimap.class, ImmutableListMultimap.of())

    return generateTreeMap(key, value);
  }

  @Generates
  static <K extends Comparable<? super K>, V> TreeMap<K, V> generateTreeMap(
      K key, @Nullable V value) {
    TreeMap<K, V> map = Maps.newTreeMap();
    map.put(key, value);
    return map;
  }

  @Generates
  static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> generateImmutableSortedMap(
      K key, V value) {

    return generateTreeMap(key, value);
  }

  @Generates
  static <K extends Comparable<? super K>, V> TreeMap<K, V> generateTreeMap(
      K key, @Nullable V value) {
    TreeMap<K, V> map = Maps.newTreeMap();
    map.put(key, value);
    return map;
  }

  @Generates
  static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> generateImmutableSortedMap(
      K key, V value) {

    /*
     * this map would contain the same exact elements as the MinMaxHeap; the
     * value in the map is the number of occurrences of the key.
     */
    SortedMap<Integer, AtomicInteger> replica = Maps.newTreeMap();
    assertTrue("Empty heap should be OK", mmHeap.isIntact());
    for (int i = 0; i < heapSize; i++) {
      int randomInt = random.nextInt();
      mmHeap.offer(randomInt);