Fix Liquid Filters and Fix DevComment Tag

app/assets/stylesheets/ltags/LiquidTags.scss

@@ -2,7 +2,7 @@
 @import 'TweetTag';
 @import 'YoutubeTag';
 @import 'GithubTag';
-@import 'CommentTag';
+@import 'DevCommentTag';
 @import 'LinkTag';
 @import 'PodcastTag';
 @import 'UserTag';

app/liquid_tags/comment_tag.rb → app/liquid_tags/dev_comment_tag.rb

@@ -1,4 +1,4 @@
-class CommentTag < LiquidTagBase
+class DevCommentTag < LiquidTagBase
   attr_reader :id_code, :comment
 
   def initialize(_tag_name, id_code, _tokens)
@@ -8,24 +8,25 @@ def initialize(_tag_name, id_code, _tokens)
 
   def render(_context)
     raise_error unless @comment
-
-    "<div class=\"liquid-comment\">" \
-      "<div class=\"details\">" \
-        "<a href=\"/#{@comment.user.username}\">" \
-          "<img class=\"profile-pic\" src=\"#{ProfileImage.new(@comment.user).get(50)}\" alt=\"#{@comment.user.username} profile image\"/>" \
-        "</a>" \
-        "<a href=\"/#{@comment.user.username}\">" \
-          "<span class=\"comment-username\">#{@comment.user.name}</span>" \
-        "</a>" \
-        "#{render_twitter_and_github}" \
-        "<div class=\"comment-date\">" \
-          "<a href=\"#{@comment.path}\">#{@comment.readable_publish_date}</a>" \
-        "</div>" \
-      "</div>" \
-      "<div class=\"body\">" \
-        + @comment.processed_html.html_safe + \
-      "</div>" \
-    "</div>"
+    <<-HTML
+    <div class="liquid-comment">
+      <div class="details">
+        <a href="/#{@comment.user.username}">
+          <img class="profile-pic" src="#{ProfileImage.new(@comment.user).get(50)}"
+            alt="#{@comment.user.username} profile image"/>
+        </a>
+        <a href="/#{@comment.user.username}">
+          <span class="comment-username">#{@comment.user.name}</span>
+        </a>
+        <div class="comment-date">
+          <a href="#{@comment.path}">#{@comment.readable_publish_date}</a>
+        </div>
+      </div>
+      <div class="body">
+        #{@comment.processed_html.html_safe}
+      </div>
+    </div>
+    HTML
   end
 
   def render_twitter_and_github
@@ -65,4 +66,4 @@ def raise_error
   end
 end
 
-Liquid::Template.register_tag("devcomment", CommentTag)
+Liquid::Template.register_tag("devcomment", DevCommentTag)

app/liquid_tags/null_tag.rb

@@ -0,0 +1,11 @@
+class NullTag < Liquid::Block
+  def initialize(_tag_name, _markup, _options)
+    raise StandardError, "Liquid##{_tag_name} tag is disabled"
+  end
+end
+
+disabled_tags = %w(assign capture case comment cycle for if ifchanged include unless)
+
+disabled_tags.each do |tag|
+  Liquid::Template.register_tag(tag, NullTag)
+end

app/liquid_tags/standard_filters.rb

@@ -1,4 +1,8 @@
 module StandardFilters
+  def append(_input)
+    raise StandardError, "Liquid#append filter is disabled"
+  end
+
   def concat(_input)
     raise StandardError, "Liquid#concat filter is disabled"
   end
@@ -15,6 +19,14 @@ def join(_input)
     raise StandardError, "Liquid#join filter is disabled"
   end
 
+  def last(_input)
+    raise StandardError, "Liquid#last filter is disabled"
+  end
+
+  def map(_input, _property)
+    raise StandardError, "Liquid#map filter is disabled"
+  end
+
   def prepend(_input, _string)
     raise StandardError, "Liquid#prepend filter is disabled"
   end
@@ -27,6 +39,10 @@ def remove_first(_input)
     raise StandardError, "Liquid#remove_first filter is disabled"
   end
 
+  def reverse(_input)
+    raise StandardError, "Liquid#reverse filter is disabled"
+  end
+
   def replace(_input)
     raise StandardError, "Liquid#replace filter is disabled"
   end
@@ -35,9 +51,25 @@ def replace_first(_input)
     raise StandardError, "Liquid#replace_first filter is disabled"
   end
 
+  def slice(_input)
+    raise StandardError, "Liquid#slice filter is disabled"
+  end
+
   def split(_input)
     raise StandardError, "Liquid#split filter is disabled"
   end
+
+  def truncate(_input)
+    raise StandardError, "Liquid#truncate filter is disabled"
+  end
+
+  def truncatewords(_input)
+    raise StandardError, "Liquid#truncatewords filter is disabled"
+  end
+
+  def uniq(_input, _property)
+    raise StandardError, "Liquid#uniq filter is disabled"
+  end
 end
 
 Liquid::Template.register_filter(StandardFilters)

app/models/comment.rb

@@ -167,8 +167,8 @@ def activity_notify
   end
 
   def custom_css
-    MarkdownParser.new(body_markdown).tags_used.map do |t|
-      Rails.application.assets["ltags/#{t}.css"].to_s
+    MarkdownParser.new(body_markdown).tags_used.map do |tag|
+      Rails.application.assets["ltags/#{tag}.css"].to_s
     end.join
   end
 

spec/liquid_tags/comment_tag_spec.rb → spec/liquid_tags/dev_comment_tag_spec.rb

@@ -1,11 +1,11 @@
 require "rails_helper"
 
-RSpec.describe CommentTag, type: :liquid_template do
+RSpec.describe DevCommentTag, type: :liquid_template do
   let(:user)        { create(:user) }
   let(:article)     { create(:article, user_id: user.id) }
   let(:comment)     { create(:comment, user_id: user.id, commentable_id: article.id) }
 
-  setup             { Liquid::Template.register_tag("devcomment", CommentTag) }
+  setup             { Liquid::Template.register_tag("devcomment", DevCommentTag) }
 
   def generate_comment_tag(id_code)
     Liquid::Template.parse("{% devcomment #{id_code} %}")

spec/liquid_tags/null_tag_spec.rb

@@ -0,0 +1,21 @@
+require "rails_helper"
+
+RSpec.describe NullTag, type: :liquid_template do
+  describe "#initialize" do
+    tags = %w(assign capture case comment cycle for if ifchanged include unless)
+
+    setup { tags.each { |tag| Liquid::Template.register_tag(tag, NullTag) } }
+
+    def generate_given_tag(tag)
+      Liquid::Template.parse("{% #{tag} %}")
+    end
+
+    context "when attempting the tags" do
+      it "prevents the tag from being used" do
+        tags.each do |tag|
+          expect { generate_given_tag(tag) }.to raise_error(StandardError)
+        end
+      end
+    end
+  end
+end