Render 404 when root comment has low score and no children (#20560)

app/controllers/comments_controller.rb

@@ -16,6 +16,11 @@ class CommentsController < ApplicationController
 
     @root_comment = Comment.find(params[:id_code].to_i(26)) if params[:id_code].present?
 
+    # hide low quality comments w/o children
+    if @root_comment && @root_comment.decorate.low_quality && !@root_comment.has_children?
+      not_found
+    end
+
     if @podcast
       @user = @podcast
       @commentable = @user.podcast_episodes.find_by(slug: params[:slug]) if @user.podcast_episodes

app/views/comments/index.html.erb

@@ -1,5 +1,5 @@
 <%= javascript_include_tag "postCommentsPage", defer: true %>
-<% if @root_comment.present? %>
+<% if @root_comment.present? && !@root_comment.decorate.low_quality %>
   <% title(@root_comment.title.to_s) %>
 <% else %>
   <% title(t("views.comments.meta.title_root", title: @commentable.title)) %>

spec/requests/comments_spec.rb

@@ -161,6 +161,27 @@ RSpec.describe "Comments" do
       end
     end
 
+    context "when the comment is low quality" do
+      let(:low_comment) do
+        create(:comment, commentable: article, user: user, score: -1000, body_markdown: "low-comment")
+      end
+
+      it "raises 404 when no children" do
+        expect do
+          get low_comment.path
+        end.to raise_error(ActiveRecord::RecordNotFound)
+      end
+
+      it "is displayed as deleted when has children", :aggregate_failures do
+        create(:comment, commentable: article, user: user, parent: low_comment,
+                         body_markdown: "child of a low-quality comment")
+        get low_comment.path
+        expect(response).to have_http_status(:ok)
+        expect(response.body).to include("Comment deleted")
+        expect(response.body).to include("child of a low-quality comment")
+      end
+    end
+
     context "when the comment is for a podcast's episode" do
       it "is successful" do
         podcast_comment = create(:comment, commentable: podcast_episode, user: user)