public async void UserDisplayName_Update_length()
        {
            Mock <IPostHistoryRepository> postHistoryRepository = new Mock <IPostHistoryRepository>();

            postHistoryRepository.Setup(x => x.Get(It.IsAny <int>())).Returns(Task.FromResult(new PostHistory()));

            var validator = new ApiPostHistoryServerRequestModelValidator(postHistoryRepository.Object);
            await validator.ValidateUpdateAsync(default(int), new ApiPostHistoryServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.UserDisplayName, new string('A', 41));
        }
        public async void RevisionGUID_Create_length()
        {
            Mock <IPostHistoryRepository> postHistoryRepository = new Mock <IPostHistoryRepository>();

            postHistoryRepository.Setup(x => x.Get(It.IsAny <int>())).Returns(Task.FromResult(new PostHistory()));

            var validator = new ApiPostHistoryServerRequestModelValidator(postHistoryRepository.Object);
            await validator.ValidateCreateAsync(new ApiPostHistoryServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.RevisionGUID, new string('A', 37));
        }
        public async void PostId_Create_Invalid_Reference()
        {
            Mock <IPostHistoryRepository> postHistoryRepository = new Mock <IPostHistoryRepository>();

            postHistoryRepository.Setup(x => x.PostByPostId(It.IsAny <int>())).Returns(Task.FromResult <Post>(null));

            var validator = new ApiPostHistoryServerRequestModelValidator(postHistoryRepository.Object);

            await validator.ValidateCreateAsync(new ApiPostHistoryServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.PostId, 1);
        }
        public async void UserId_Update_Invalid_Reference()
        {
            Mock <IPostHistoryRepository> postHistoryRepository = new Mock <IPostHistoryRepository>();

            postHistoryRepository.Setup(x => x.UserByUserId(It.IsAny <int>())).Returns(Task.FromResult <User>(null));

            var validator = new ApiPostHistoryServerRequestModelValidator(postHistoryRepository.Object);

            await validator.ValidateUpdateAsync(default(int), new ApiPostHistoryServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.UserId, 1);
        }