private void  TestTermVectors()
        {
            // check:
            int  numDocs = reader.NumDocs();
            long start   = 0L;

            for (int docId = 0; docId < numDocs; docId++)
            {
                start = (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond);
                TermFreqVector[] vectors = reader.GetTermFreqVectors(docId);
                timeElapsed += (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond) - start;

                // verify vectors result
                VerifyVectors(vectors, docId);

                start = (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond);
                TermFreqVector vector = reader.GetTermFreqVector(docId, "field");
                timeElapsed += (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond) - start;

                vectors    = new TermFreqVector[1];
                vectors[0] = vector;

                VerifyVectors(vectors, docId);
            }
        }