public void Find_No_Available_Doctors()
        {
            DoctorService service = new DoctorService(CreateOperationStubRepository(), CreateAppointmentStubRepository(), CreateScheduleStubRepository(), CreateDoctorStubRepository());

            List <DoctorUser> appointments = service.GetAvailableDoctors("Pulmonology", "02/02/2020", 2);

            appointments.ShouldBeEmpty();
        }