public virtual void TestNRTAndCommit()
        {
            Directory           dir       = NewDirectory();
            NRTCachingDirectory cachedDir = new NRTCachingDirectory(dir, 2.0, 25.0);
            MockAnalyzer        analyzer  = new MockAnalyzer(Random);

            analyzer.MaxTokenLength = TestUtil.NextInt32(Random, 1, IndexWriter.MAX_TERM_LENGTH);
            IndexWriterConfig conf = NewIndexWriterConfig(TEST_VERSION_CURRENT, analyzer);
            RandomIndexWriter w    = new RandomIndexWriter(Random, cachedDir, conf);
            LineFileDocs      docs = new LineFileDocs(Random, DefaultCodecSupportsDocValues);
            int numDocs            = TestUtil.NextInt32(Random, 100, 400);

            if (Verbose)
            {
                Console.WriteLine("TEST: numDocs=" + numDocs);
            }

            IList <BytesRef> ids = new List <BytesRef>();
            DirectoryReader  r   = null;

            for (int docCount = 0; docCount < numDocs; docCount++)
            {
                Document doc = docs.NextDoc();
                ids.Add(new BytesRef(doc.Get("docid")));
                w.AddDocument(doc);
                if (Random.Next(20) == 17)
                {
                    if (r == null)
                    {
                        r = DirectoryReader.Open(w.IndexWriter, false);
                    }
                    else
                    {
                        DirectoryReader r2 = DirectoryReader.OpenIfChanged(r);
                        if (r2 != null)
                        {
                            r.Dispose();
                            r = r2;
                        }
                    }
                    Assert.AreEqual(1 + docCount, r.NumDocs);
                    IndexSearcher s = NewSearcher(r);
                    // Just make sure search can run; we can't assert
                    // totHits since it could be 0
                    TopDocs hits = s.Search(new TermQuery(new Term("body", "the")), 10);
                    // System.out.println("tot hits " + hits.totalHits);
                }
            }

            if (r != null)
            {
                r.Dispose();
            }

            // Close should force cache to clear since all files are sync'd
            w.Dispose();

            string[] cachedFiles = cachedDir.ListCachedFiles();
            foreach (string file in cachedFiles)
            {
                Console.WriteLine("FAIL: cached file " + file + " remains after sync");
            }
            Assert.AreEqual(0, cachedFiles.Length);

            r = DirectoryReader.Open(dir);
            foreach (BytesRef id in ids)
            {
                Assert.AreEqual(1, r.DocFreq(new Term("docid", id)));
            }
            r.Dispose();
            cachedDir.Dispose();
            docs.Dispose();
        }