Assign blog post in controller

We attempt to make the acceptance test pass by assigning the @blog_post instance variable in the controller. Note that we don't create a unit test for the controller. Many developers discourage controller tests because controller behavior is so closely related to acceptance test cases. Also, Rails 5 removes some controller test features that result in limiting how effective they can be.

Red: uninitialized constant BlogPostsController::BlogPost

The line of code we added isn't actually able to succeed because there is no class named BlogPost defined yet.

app/controllers/blog_posts_controller.rb

@@ -1,4 +1,5 @@
 class BlogPostsController < ApplicationController
   def new
+    @blog_post = BlogPost.new
   end
 end