private void VerifyDocFreq()
{
IndexReader reader = IndexReader.Open(dir);
TermEnum termEnum = null;
// create enumeration of all terms
termEnum = reader.Terms();
// go to the first term (aaa)
termEnum.Next();
// assert that term is 'aaa'
Assert.AreEqual("aaa", termEnum.Term().Text());
Assert.AreEqual(200, termEnum.DocFreq());
// go to the second term (bbb)
termEnum.Next();
// assert that term is 'bbb'
Assert.AreEqual("bbb", termEnum.Term().Text());
Assert.AreEqual(100, termEnum.DocFreq());
termEnum.Close();
// create enumeration of terms after term 'aaa', including 'aaa'
termEnum = reader.Terms(new Term("content", "aaa"));
// assert that term is 'aaa'
Assert.AreEqual("aaa", termEnum.Term().Text());
Assert.AreEqual(200, termEnum.DocFreq());
// go to term 'bbb'
termEnum.Next();
// assert that term is 'bbb'
Assert.AreEqual("bbb", termEnum.Term().Text());
Assert.AreEqual(100, termEnum.DocFreq());
termEnum.Close();
}