public void RemovePresentationThrowsExceptionIfPresentationDoesNotExist()
        {
            var target = new DatabaseContext();
            target.RemovePresentation(99);

        }
        public void RemovePresentationTest()
        {
            var target = new DatabaseContext();
            var presentation = TestPresentation();
            var db = new PresentationsEntities();
            db.Presentations.Add(presentation);
            db.SaveChanges();
            Assert.IsTrue(db.Presentations.Any(p => p.PresentationId == presentation.PresentationId));
            target.RemovePresentation(presentation.PresentationId);
            var result = db.Presentations.Any(p => p.PresentationId == presentation.PresentationId);
            Assert.IsFalse(result);

        }