### Question:
VocabularyHolder implements Serializable { public int numWords() { return vocabulary.size(); } protected  VocabularyHolder(); protected  VocabularyHolder(@NonNull VocabCache<? extends SequenceElement> cache, boolean markAsSpecial); static HuffmanNode buildNode(List<Byte> codes, List<Integer> points, int codeLen, int index); void transferBackToVocabCache(); void transferBackToVocabCache(VocabCache cache); void transferBackToVocabCache(VocabCache cache, boolean emptyHolder); static List<Byte> arrayToList(byte[] array, int codeLen); static byte[] listToArray(List<Byte> code); static int[] listToArray(List<Integer> points, int codeLen); static List<Integer> arrayToList(int[] array, int codeLen); Collection<VocabularyWord> getVocabulary(); VocabularyWord getVocabularyWordByString(String word); VocabularyWord getVocabularyWordByIdx(Integer id); boolean containsWord(String word); void incrementWordCounter(String word); void addWord(String word); void addWord(VocabularyWord word); void consumeVocabulary(VocabularyHolder holder); void resetWordCounters(); int numWords(); void truncateVocabulary(); void truncateVocabulary(int threshold); List<VocabularyWord> updateHuffmanCodes(); int indexOf(String word); List<VocabularyWord> words(); long totalWordsBeyondLimit();  }### Answer:
@Test public void testConstructor() throws Exception { InMemoryLookupCache cache = new InMemoryLookupCache(true); VocabularyHolder holder = new VocabularyHolder(cache, false); assertEquals(0, holder.numWords()); }