Lucene.Net.Index.TestSnapshotDeletionPolicy.TestRollbackToOldSnapshot C# (CSharp) Method

        public virtual void TestRollbackToOldSnapshot()
        {
            int numSnapshots = 2;
            Directory dir = NewDirectory();

            SnapshotDeletionPolicy sdp = DeletionPolicy;
            IndexWriter writer = new IndexWriter(dir, GetConfig(Random(), sdp));
            PrepareIndexAndSnapshots(sdp, writer, numSnapshots);
            writer.Dispose();

            // now open the writer on "snapshot0" - make sure it succeeds
            writer = new IndexWriter(dir, GetConfig(Random(), sdp).SetIndexCommit(Snapshots[0]));
            // this does the actual rollback
            writer.Commit();
            writer.DeleteUnusedFiles();
            AssertSnapshotExists(dir, sdp, numSnapshots - 1, false);
            writer.Dispose();

            // but 'snapshot1' files will still exist (need to release snapshot before they can be deleted).
            string segFileName = Snapshots[1].SegmentsFileName;
            Assert.IsTrue(SlowFileExists(dir, segFileName), "snapshot files should exist in the directory: " + segFileName);

            dir.Dispose();
        }