public void deletePostsWithTag(Tag tag) { for (Post post : blogService.getAllPosts()) { if (post.getTags().contains(tag)) { blogService.deletePost(post.getId()); } } }

public class FakeBlogService implements BlogService { private final Set<Post> posts = new HashSet<Post>(); // Store posts in memory public void addPost(Post post) { posts.add(post); } public void deletePost( int id) { for (Post post : posts) { if (post.getId() == id) { posts.remove(post); return ; } } throw new PostNotFoundException( "No post with ID " + id); } public Set<Post> getAllPosts() { return posts; } }