post votes: fix exception when voting on posts using API.

Fix an `undefined method post_vote_url` exception when doing
`POST https://danbooru.donmai.us/posts/1/votes.json`.

Also add the following API endpoints:

* https://danbooru.donmai.us/post_votes/:id.json
* https://danbooru.donmai.us/comment_votes/:id.json
* https://danbooru.donmai.us/forum_post_votes/:id.json

where `:id` is the vote ID, not the post ID.

app/controllers/comment_votes_controller.rb

@@ -8,6 +8,11 @@ class CommentVotesController < ApplicationController
     respond_with(@comment_votes)
   end
 
+  def show
+    @comment_vote = authorize CommentVote.find(params[:id])
+    respond_with(@comment_vote)
+  end
+
   def create
     @comment = Comment.find(params[:comment_id])
 

app/controllers/forum_post_votes_controller.rb

@@ -8,6 +8,11 @@ class ForumPostVotesController < ApplicationController
     respond_with(@forum_post_votes)
   end
 
+  def show
+    @forum_post_vote = authorize ForumPostVote.find(params[:id])
+    respond_with(@forum_post_vote)
+  end
+
   def create
     @forum_post = ForumPost.find(params[:forum_post_id])
     @forum_post_vote = authorize ForumPostVote.new(creator: CurrentUser.user, forum_post: @forum_post, **permitted_attributes(ForumPostVote))

app/controllers/post_votes_controller.rb

@@ -8,6 +8,11 @@ class PostVotesController < ApplicationController
     respond_with(@post_votes)
   end
 
+  def show
+    @post_vote = authorize PostVote.find(params[:id])
+    respond_with(@post_vote)
+  end
+
   def create
     @post = Post.find(params[:post_id])
 

app/policies/comment_vote_policy.rb

@@ -7,6 +7,10 @@ class CommentVotePolicy < ApplicationPolicy
     !record.is_deleted? && (record.user_id == user.id || user.is_admin?)
   end
 
+  def show?
+    can_see_votes? || record.user == user
+  end
+
   def can_see_votes?
     user.is_moderator?
   end

app/policies/post_vote_policy.rb

@@ -6,4 +6,8 @@ class PostVotePolicy < ApplicationPolicy
   def destroy?
     unbanned? && record.user == user
   end
+
+  def show?
+    user.is_admin? || record.user == user
+  end
 end

config/routes.rb

@@ -89,7 +89,7 @@ Rails.application.routes.draw do
       post :approve
     end
   end
-  resources :comment_votes, only: [:index, :destroy]
+  resources :comment_votes, only: [:index, :show, :destroy]
   resources :comments do
     resource :votes, controller: "comment_votes", only: [:create, :destroy], as: "comment_votes"
     collection do
@@ -134,7 +134,7 @@ Rails.application.routes.draw do
       get :search
     end
   end
-  resources :forum_post_votes, only: [:index, :create, :destroy]
+  resources :forum_post_votes, only: [:index, :show, :create, :destroy]
   resources :forum_topics do
     member do
       post :undelete
@@ -189,7 +189,7 @@ Rails.application.routes.draw do
   end
   resources :post_regenerations, :only => [:create]
   resources :post_replacements, :only => [:index, :new, :create, :update]
-  resources :post_votes, only: [:index]
+  resources :post_votes, only: [:index, :show]
 
   # XXX Use `only: []` to avoid redefining post routes defined at top of file.
   resources :posts, only: [] do

test/functional/comment_votes_controller_test.rb

@@ -53,12 +53,40 @@ class CommentVotesControllerTest < ActionDispatch::IntegrationTest
       end
     end
 
+    context "show action" do
+      setup do
+        @comment_vote = create(:comment_vote, comment: @comment, user: @user)
+      end
+
+      should "show the vote to the voter" do
+        get_auth comment_vote_path(@comment_vote), @user, as: :json
+        assert_response :success
+      end
+
+      should "show the vote to moderators" do
+        get_auth comment_vote_path(@comment_vote), create(:moderator_user), as: :json
+        assert_response :success
+      end
+
+      should "not show the vote to other users" do
+        get_auth comment_vote_path(@comment_vote), create(:user), as: :json
+        assert_response 403
+      end
+    end
+
     context "create action" do
       setup do
         @user = create(:user)
         @comment = create(:comment)
       end
 
+      should "work for a JSON response" do
+        post_auth comment_comment_votes_path(comment_id: @comment.id), @user, params: { score: 1, format: "json" }
+
+        assert_response 201
+        assert_equal(1, @comment.reload.score)
+      end
+
       should "not allow anonymous users to vote" do
         post comment_comment_votes_path(comment_id: @comment.id, score: "1"), xhr: true
         assert_response 403

test/functional/forum_post_votes_controller_test.rb

@@ -34,7 +34,22 @@ class ForumPostVotesControllerTest < ActionDispatch::IntegrationTest
       end
     end
 
+    context "show action" do
+      should "show the vote to all users" do
+        @forum_post_vote = create(:forum_post_vote, forum_post: @forum_post)
+        get forum_post_vote_path(@forum_post_vote), as: :json
+        assert_response :success
+      end
+    end
+
     context "create action" do
+      should "work for a JSON response" do
+        post_auth forum_post_votes_path, @user, params: { forum_post_id: @forum_post.id, forum_post_vote: { score: 1 }}, as: :json
+
+        assert_response 201
+        assert_equal(1, @forum_post.votes.count)
+      end
+
       should "allow members to vote" do
         assert_difference("ForumPostVote.count", 1) do
           post_auth forum_post_votes_path(format: :js), @user, params: { forum_post_id: @forum_post.id, forum_post_vote: { score: 1 }}

test/functional/post_votes_controller_test.rb

@@ -44,7 +44,35 @@ class PostVotesControllerTest < ActionDispatch::IntegrationTest
       end
     end
 
+    context "show action" do
+      setup do
+        @post_vote = create(:post_vote, post: @post, user: @user)
+      end
+
+      should "show the vote to the voter" do
+        get_auth post_vote_path(@post_vote), @user, as: :json
+        assert_response :success
+      end
+
+      should "show the vote to admins" do
+        get_auth post_vote_path(@post_vote), create(:admin_user), as: :json
+        assert_response :success
+      end
+
+      should "not show the vote to other users" do
+        get_auth post_vote_path(@post_vote), create(:user), as: :json
+        assert_response 403
+      end
+    end
+
     context "create action" do
+      should "work for a JSON response" do
+        post_auth post_post_votes_path(post_id: @post.id), @user, params: { score: 1, format: "json" }
+
+        assert_response 201
+        assert_equal(1, @post.reload.score)
+      end
+
       should "not allow anonymous users to vote" do
         post post_post_votes_path(post_id: @post.id), params: { score: 1, format: "js" }