public new void SnapshotTest() {

        string dbName = "wal_autotest.db";

        string walDBConStr = String.Format("DataSource =\"{0}\";JournalMode=\"WAL\";Pooling=false", dbName);
        SQLiteConnection dbConnection = new SQLiteConnection(walDBConStr);
        TryCreateDatabase(dbName, walDBConStr, dbConnection);

        dbConnection.Open();
        DropForSnapshot(walDBConStr);
        InsertForSnapshot(walDBConStr);

        string schema = "main";
        SQLiteSnapshot snapshot = SQLiteSnapshot.Get(dbConnection); // snapshot with 1 row exists

        long cnt1 = GetCountSnapshot(dbConnection); // returns 1

        using (var trans = dbConnection.BeginTransaction(SQLiteTransactionMode.Deferred)) {

                var snap1 = InsertForSnapshot(walDBConStr); //insert new row and returns last snapshot

                snap1.Open(schema, trans);
                long cnt22 = GetCountSnapshot(dbConnection); // returns 2

                var snap2 = InsertForSnapshot(walDBConStr); 

                long cnt222 = GetCountSnapshot(dbConnection); // returns 2

                snap2.Open(trans); // apply last snapshot to the current transaction on default("main") shcema
                long cnt3 = GetCountSnapshot(dbConnection); // currently transaction can read latest data. returns 3

                int compare = snap1.CompareTo(snap2);
                var equal = snap1.Equals(snap2);

                trans.Rollback();
        }

        var dbConnection2 = new SQLiteConnection(walDBConStr);
        dbConnection2.Open();

        InsertForSnapshot(walDBConStr);

        SQLiteSnapshot.Recover(dbConnection2); //Make all snapsots in WAL file available for current connection

        using (var trans = dbConnection2.BeginTransaction(SQLiteTransactionMode.Deferred)) {

                long cnt_4 = GetCountSnapshot(dbConnection2); // returns 4. latest snapshot by default

                if (cnt_4 != 4)
                        throw new Exception("should be 3 rows");

                snapshot.Open(trans); // apply first snapshot to the current transaction
                long cnt_1 = GetCountSnapshot(dbConnection2); // returns 1. because snapshot points to the state, when 1 row was inserted

                trans.Rollback();
        }

        dbConnection.Close();
        dbConnection2.Close();
}

private static bool TryCreateDatabase(string dbName, string walDBConStr, SQLiteConnection dbConnection) {


        bool isInsert = false; 
        if (!File.Exists(dbName)) {

                File.WriteAllText(dbName, "");
                isInsert = true;
        }
      
        if (isInsert) {
                dbConnection.Open();

                SQLiteCommand cmd = (SQLiteCommand)dbConnection.CreateCommand();
                cmd.CommandText = "Create table blob_types (id int, f_blob int)";
                cmd.ExecuteNonQuery();
                cmd.Dispose();

                dbConnection.Close();
        }

        return isInsert;
}

private long GetCountSnapshot(SQLiteConnection dbConnection) {
        SQLiteCommand cmd = (SQLiteCommand)dbConnection.CreateCommand();
        cmd.CommandText = "select count(id) from blob_types";
        var ob = cmd.ExecuteScalar();
        cmd.Dispose();

        return (long)ob;
}

private void DropForSnapshot(string walDBConStr) {

        SQLiteConnection dbConnection = new SQLiteConnection(walDBConStr);
        dbConnection.Open();
        using (var trans = dbConnection.BeginTransaction(IsolationLevel.ReadCommitted)) {
                //result = trans.GetSnapshot();

                SQLiteCommand cmd = (SQLiteCommand)dbConnection.CreateCommand();
                cmd.CommandText = "delete from blob_types";
                cmd.ExecuteNonQuery();
                cmd.Dispose();

                trans.Commit();
        }
}

private SQLiteSnapshot InsertForSnapshot(string walDBConStr) {

        SQLiteSnapshot result = null;
        SQLiteConnection dbConnection = new SQLiteConnection(walDBConStr);
        dbConnection.Open();
        using (var trans = dbConnection.BeginTransaction(IsolationLevel.ReadCommitted)) {
                //result = trans.GetSnapshot();

                SQLiteCommand cmd = (SQLiteCommand)dbConnection.CreateCommand();
                cmd.CommandText = "insert into blob_types (id, f_blob) values (1, :blob)";
                cmd.Parameters.Add(CreateParameter("blob", 1));
                cmd.ExecuteNonQuery();
                cmd.Dispose();

                trans.Commit();
        }

        using (var trans = dbConnection.BeginTransaction(IsolationLevel.ReadCommitted)) {
                result = SQLiteSnapshot.Get(trans);
        }

        dbConnection.Close();

        return result;
}