public void ShouldThrowExceptionWhenGetTagsByNameFails()
{
_tagRepository = new Mock<ITagRepository>();
_tagRepository.Setup(a => a.Find(It.IsAny<Expression<Func<Tag, bool>>>(), null, string.Empty))
.Throws(new Exception());
_postRepository = new Mock<IPostRepository>();
_tagsLogic = new TagsLogic(_tagRepository.Object, _postRepository.Object);
Assert.Throws<BlogException>(() => _tagsLogic.GetTagsByName("foo"));
}