private List <string> Initialize()
        {
            List <string> outputLines = new List <string>();

            _os = new OfferSystem();
            TestOutputWriter writer = new TestOutputWriter(outputLines);

            _interpreter = new OfferInterpreter(writer);

            return(outputLines);
        }
 private void ClearOfferSystem()
 {
     _os = new OfferSystem();
 }