Simplify post followed by user method

app/controllers/comments_controller.rb

@@ -276,7 +276,7 @@ def post
 
   def post_follow
     @post = Post.find(params[:post_id])
-    if CommentThread.post_followed?(@post, current_user)
+    if @post.followed_by?(current_user)
       ThreadFollower.where(post: @post, user: current_user).destroy_all
     else
       ThreadFollower.create(post: @post, user: current_user)

app/models/comment_thread.rb

@@ -16,14 +16,6 @@ class CommentThread < ApplicationRecord
 
   after_create :create_follower
 
-  # Are there any threads on a given post that a given user follows?
-  # @param post [Post] post to check
-  # @param user [User] user to check
-  # @return [Boolean] check result
-  def self.post_followed?(post, user)
-    ThreadFollower.where(post: post, user: user).any?
-  end
-
   # Is the thread read-only (can't be edited)?
   # @return [Boolean] check result
   def read_only?

app/models/post.rb

@@ -234,6 +234,14 @@ def reaction_list
              .to_h { |_k, v| [v.first.reaction_type, v] }
   end
 
+  # Are new threads on this post followed by a given user?
+  # @param post [Post] post to check
+  # @param user [User] user to check
+  # @return [Boolean] check result
+  def followed_by?(user)
+    ThreadFollower.where(post: self, user: user).any?
+  end
+
   private
 
   ##

app/views/posts/_expanded.html.erb

@@ -532,7 +532,7 @@
             <%= pluralize(public_count, 'comment thread') %>
           </h4>
           <% if user_signed_in? %>
-            <% if CommentThread.post_followed?(post, current_user) %>
+            <% if post.followed_by?(current_user) %>
               <%= link_to follow_post_comments_path(post_id: post.id), method: :post,
                           class: "button is-muted is-outlined is-small",
                           title: 'Don\'t follow new comment threads on this post',

test/comments_test_helpers.rb

@@ -71,6 +71,18 @@ def try_unfollow_thread(thread)
     post :thread_unrestrict, params: { id: thread.id, type: 'follow' }
   end
 
+  # Attempts to follow new threads on a given post
+  # @param post [Post] post to follow
+  def try_post_follow(test_post)
+    post :post_follow, params: { post_id: test_post.id }
+  end
+
+  # Attempts to unfollow new threads on a given post
+  # @param post [Post] post to unfollow
+  def try_post_unfollow(test_post)
+    post :post_follow, params: { post_id: test_post.id }
+  end
+
   # Attempts to lock a given comment thread
   # @param thread [CommentThread] thread to lock
   # @param duration [Integer] lock duration, in days

test/controllers/comments/post_follow_test.rb

@@ -0,0 +1,37 @@
+require 'test_helper'
+require 'comments_test_helpers'
+
+class CommentsControllerTest < ActionController::TestCase
+  include Devise::Test::ControllerHelpers
+  include CommentsControllerTestHelpers
+
+  test 'post follower can unfollow post' do
+    user = users(:standard_user)
+    sign_in user
+    question = posts(:question_one)
+
+    # Assert user follows post
+    assert_equal 1, ThreadFollower.where(['post_id = ? AND user_id = ?', question, user]).count
+
+    try_post_unfollow(question)
+    assert_response(:found)
+
+    # Assert user does not follow post
+    assert_equal 0, ThreadFollower.where(['post_id = ? AND user_id = ?', question, user]).count
+  end
+
+  test 'non-follower can follow post' do
+    user = users(:basic_user)
+    sign_in user
+    question = posts(:question_one)
+
+    # Assert user does not follow post
+    assert_equal 0, ThreadFollower.where(['post_id = ? AND user_id = ?', question, user]).count
+
+    try_post_follow(question)
+    assert_response(:found)
+
+    # Assert user follows post
+    assert_equal 1, ThreadFollower.where(['post_id = ? AND user_id = ?', question, user]).count
+  end
+end

test/fixtures/thread_followers.yml

@@ -5,3 +5,7 @@ deleter_normal:
 standard_author_normal:
   user: standard_user
   comment_thread: normal
+
+standard_author_question_one:
+  user: standard_user
+  post: question_one