### Question:
Synset extends PointerTarget implements DictionaryElement { public int indexOfWord(String lemma) { checkLemmaIsNotNull(lemma); for (int i = 0; i < words.size(); i++) { if (words.get(i).getLemma().equalsIgnoreCase(lemma)) { return i; } } return -1; } Synset(Dictionary dictionary, POS pos);  Synset(Dictionary dictionary, POS pos, long offset); DictionaryElementType getType(); Object getKey(); POS getPOS(); boolean equals(Object object); int hashCode(); String toString(); @Override Synset getSynset(); @Override int getIndex(); List<Pointer> getPointers(); String getGloss(); void setGloss(String gloss); List<Word> getWords(); long getOffset(); void setOffset(long offset); boolean isAdjectiveCluster(); void setIsAdjectiveCluster(boolean isAdjectiveCluster); String[] getVerbFrames(); BitSet getVerbFrameFlags(); void setVerbFrameFlags(BitSet verbFrameFlags); int[] getVerbFrameIndices(); boolean containsWord(String lemma); int indexOfWord(String lemma); long getLexFileNum(); void setLexFileNum(long lexFileNum); String getLexFileName(); @Override void setDictionary(Dictionary dictionary);  }### Answer:
@Test(expected = IllegalArgumentException.class) public void testIndexOfWordNull() throws JWNLException { testObj.indexOfWord(null); }
@Test public void testIndexOfWordNegative() throws JWNLException { Assert.assertEquals(-1, testObj.indexOfWord("lemma")); }