public void Given_a_BlogPost_that_has_a_status_of_Published_When_it_is_published_Then_an_BlogPostAlreadyPublishedException_should_be_Thrown() { // Given. BlogPost blogPost = PublishedBlogPost.Create(); // When. Action action = () => blogPost.Publish(); // Then. action.Should().Throw <BlogPostAlreadyPublishedException>("Because blog posts cannot be published more than once"); }