Originally posted by Layne Wakerell: The Data.class needs to implement the DB interface. Does this mean the Data.class can have any constructor you like? e.g. DB database = new Data("filename.db"); or DB database = new Data(new File("filename.db")); or even DB database = new Data();//where the database file is hardcoded in the Data.class How will the automated test tool create an instance of our Data.class???