private InputHandler GetSubjectWithMessagesPosted()
        {
            var subject = new InputHandler(GetDateDiffProvider());
            var inputs  = new List <string>
            {
                aliceInput1,
                bobInput1,
                bobInput2,
                charlieInput1
            };

            foreach (var input in inputs)
            {
                subject.AcceptInput(input);
            }

            return(subject);
        }