public void ShouldAddTag()
{
var tag = new Common.Contracts.Tag {TagName = "foo"};
_tagRepository = new Mock<ITagRepository>();
_tagRepository.Setup(a => a.Add(It.IsAny<Tag>())).Returns(new Tag { TagName = "foo" });
_tagRepository.Setup(a => a.Find(It.IsAny<Expression<Func<Tag, bool>>>(),
It.IsAny<Func<IQueryable<Tag>, IOrderedQueryable<Tag>>>(), It.IsAny<string>()))
.Returns(new List<Tag>());
_postRepository = new Mock<IPostRepository>();
_tagsLogic = new TagsLogic(_tagRepository.Object, _postRepository.Object);
var result = _tagsLogic.Add(tag);
Assert.NotNull(result);
Assert.IsNull(result.Error);
}