User can create posts

For testing a controller, what you want to do is something like:

```
# some logic for logging in a user
post :create_post, :title => "New", :content => "Info"
expect(Post.last.title).to eq("New")
```

That's pseudocode, but the idea is that you actually make a POST request, and check the result.

Here's an article that might help: https://semaphoreapp.com/blog/2014/02/11/rails-testing-antipatterns-controllers.html