public async void TagName_Update_null()
        {
            Mock <ITagRepository> tagRepository = new Mock <ITagRepository>();

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

            var validator = new ApiTagServerRequestModelValidator(tagRepository.Object);
            await validator.ValidateUpdateAsync(default(int), new ApiTagServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.TagName, null as string);
        }
        public async void ExcerptPostId_Update_Valid_Reference()
        {
            Mock <ITagRepository> tagRepository = new Mock <ITagRepository>();

            tagRepository.Setup(x => x.PostByExcerptPostId(It.IsAny <int>())).Returns(Task.FromResult <Post>(new Post()));

            var validator = new ApiTagServerRequestModelValidator(tagRepository.Object);
            await validator.ValidateUpdateAsync(default(int), new ApiTagServerRequestModel());

            validator.ShouldNotHaveValidationErrorFor(x => x.ExcerptPostId, 1);
        }
        public async void TagName_Create_length()
        {
            Mock <ITagRepository> tagRepository = new Mock <ITagRepository>();

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

            var validator = new ApiTagServerRequestModelValidator(tagRepository.Object);
            await validator.ValidateCreateAsync(new ApiTagServerRequestModel());

            validator.ShouldHaveValidationErrorFor(x => x.TagName, new string('A', 151));
        }
        public async void WikiPostId_Create_Invalid_Reference()
        {
            Mock <ITagRepository> tagRepository = new Mock <ITagRepository>();

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

            var validator = new ApiTagServerRequestModelValidator(tagRepository.Object);

            await validator.ValidateCreateAsync(new ApiTagServerRequestModel());

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