MutableWordUse { public MutableWordUse combine(final MutableWordUse that) { if (wordIdentifier == null) { wordIdentifier = that.wordIdentifier; } else if (that.wordIdentifier != null) { wordIdentifier = PreferredFormTool.preferredForm(wordIdentifier, that.wordIdentifier); } lineNos.addAll(that.lineNos); return this; }  void accumulate(final AnalysisRecord record); MutableWordUse combine(final MutableWordUse that); WordUse toWordUse();  }
@Test public void testCombineBothEmpty() { MutableWordUse rhs = new MutableWordUse(); target.combine(rhs); assertThrows(VocabHunterException.class, target::toWordUse); }