CacheBuster refactoring (#4766)

* Turn CacheBuster into a module

This class used no internal state, so repeatedly creating short-lived objects seems wasteful.

* Consistently use string interpolation and parenthesis

* Destructure arrays into meaningful names, formatting

* Fix request spec for internal classified listings controller

Interestingly this works when asserting directly on the module, but not on a double.
Asserting directly in the module seems sufficient for this test so the indirection
was removed.

* Turn CacheBuster into a module

This class used no internal state, so repeatedly creating short-lived objects seems wasteful.

* Fix specs after rebasing

app/controllers/internal/articles_controller.rb

@@ -38,7 +38,7 @@ class Internal::ArticlesController < Internal::ApplicationController
     article.user_id = article_params[:user_id].to_i
     article.update!(article_params)
     Article.where.not(id: article.id).where(live_now: true).update_all(live_now: false) if article.live_now
-    CacheBuster.new.bust "/live_articles"
+    CacheBuster.bust("/live_articles")
     render body: nil
   end
 

app/controllers/internal/events_controller.rb

@@ -27,7 +27,7 @@ module Internal
       @event = Event.find(params[:id])
       @events = Event.order("starts_at DESC")
       if @event.update(event_params)
-        CacheBuster.new.bust "/live_articles"
+        CacheBuster.bust("/live_articles")
         flash[:success] = "#{@event.title} was successfully updated"
         redirect_to "/internal/events"
       else

app/controllers/internal/tools_controller.rb

@@ -35,15 +35,14 @@ class Internal::ToolsController < Internal::ApplicationController
   def handle_article_cache
     article = Article.find(params[:bust_article].to_i)
     article.touch(:last_commented_at)
-    CacheBuster.new.bust_article(article)
+    CacheBuster.bust_article(article)
   end
 
   def bust_link(link)
-    cb = CacheBuster.new
     link.sub!("https://dev.to", "") if link.starts_with?("https://dev.to")
-    cb.bust(link)
-    cb.bust(link + "/")
-    cb.bust(link + "?i=i")
-    cb.bust(link + "/?i=i")
+    CacheBuster.bust(link)
+    CacheBuster.bust("#{link}/")
+    CacheBuster.bust("#{link}?i=i")
+    CacheBuster.bust("#{link}/?i=i")
   end
 end

app/controllers/profile_pins_controller.rb

@@ -31,7 +31,7 @@ class ProfilePinsController < ApplicationController
   end
 
   def bust_user_profile
-    CacheBuster.new.bust(current_user.path)
-    CacheBuster.new.bust(current_user.path + "?i=i")
+    CacheBuster.bust(current_user.path)
+    CacheBuster.bust("#{current_user.path}?i=i")
   end
 end

app/jobs/articles/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Articles
   class BustCacheJob < ApplicationJob
     queue_as :articles_bust_cache
 
-    def perform(article_id, cache_buster = CacheBuster.new)
+    def perform(article_id, cache_buster = CacheBuster)
       article = Article.find_by(id: article_id)
 
       cache_buster.bust_article(article) if article

app/jobs/articles/bust_multiple_caches_job.rb

@@ -2,10 +2,10 @@ module Articles
   class BustMultipleCachesJob < ApplicationJob
     queue_as :articles_bust_multiple_caches
 
-    def perform(article_ids, cache_buster = CacheBuster.new)
+    def perform(article_ids, cache_buster = CacheBuster)
       Article.select(:id, :path).where(id: article_ids).find_each do |article|
         cache_buster.bust(article.path)
-        cache_buster.bust(article.path + "?i=i")
+        cache_buster.bust("#{article.path}?i=i")
       end
     end
   end

app/jobs/classified_listings/bust_cache_job.rb

@@ -2,7 +2,7 @@ module ClassifiedListings
   class BustCacheJob < ApplicationJob
     queue_as :classified_listings_bust_cache
 
-    def perform(classified_listing_id, cache_buster = CacheBuster.new)
+    def perform(classified_listing_id, cache_buster = CacheBuster)
       classified_listing = ClassifiedListing.find_by(id: classified_listing_id)
 
       return unless classified_listing

app/jobs/events/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Events
   class BustCacheJob < ApplicationJob
     queue_as :events_bust_cache
 
-    def perform(cache_buster = CacheBuster.new)
+    def perform(cache_buster = CacheBuster)
       cache_buster.bust_events
     end
   end

app/jobs/organizations/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Organizations
   class BustCacheJob < ApplicationJob
     queue_as :organizations_bust_cache
 
-    def perform(organization_id, slug, cache_buster = CacheBuster.new)
+    def perform(organization_id, slug, cache_buster = CacheBuster)
       organization = Organization.find_by(id: organization_id)
 
       return unless organization

app/jobs/pages/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Pages
   class BustCacheJob < ApplicationJob
     queue_as :pages_bust_cache
 
-    def perform(slug, cache_buster = CacheBuster.new)
+    def perform(slug, cache_buster = CacheBuster)
       cache_buster.bust_page(slug)
     end
   end

app/jobs/podcast_episodes/bust_cache_job.rb

@@ -2,7 +2,7 @@ module PodcastEpisodes
   class BustCacheJob < ApplicationJob
     queue_as :podcast_episodes_bust_cache
 
-    def perform(podcast_episode_id, path, podcast_slug, cache_buster = CacheBuster.new)
+    def perform(podcast_episode_id, path, podcast_slug, cache_buster = CacheBuster)
       podcast_episode = PodcastEpisode.find_by(id: podcast_episode_id)
       return unless podcast_episode
 

app/jobs/podcasts/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Podcasts
   class BustCacheJob < ApplicationJob
     queue_as :podcasts_bust_cache
 
-    def perform(path, cache_buster = CacheBuster.new)
+    def perform(path, cache_buster = CacheBuster)
       cache_buster.bust_podcast(path)
     end
   end

app/jobs/reactions/bust_homepage_cache_job.rb

@@ -2,7 +2,7 @@ module Reactions
   class BustHomepageCacheJob < ApplicationJob
     queue_as :bust_homepage_cache_from_reactions
 
-    def perform(reaction_id, cache_buster = CacheBuster.new)
+    def perform(reaction_id, cache_buster = CacheBuster)
       reaction = Reaction.find_by(id: reaction_id, reactable_type: "Article")
       return unless reaction&.reactable
 
@@ -10,10 +10,10 @@ module Reactions
       return unless featured_articles_ids.include?(reaction.reactable_id)
 
       reaction.reactable.touch
-      cache_buster.bust "/"
-      cache_buster.bust "/"
-      cache_buster.bust "/?i=i"
-      cache_buster.bust "?i=i"
+      cache_buster.bust("/")
+      cache_buster.bust("/")
+      cache_buster.bust("/?i=i")
+      cache_buster.bust("?i=i")
     end
   end
 end

app/jobs/reactions/bust_reactable_cache_job.rb

@@ -2,7 +2,7 @@ module Reactions
   class BustReactableCacheJob < ApplicationJob
     queue_as :bust_reactable_cache
 
-    def perform(reaction_id, cache_buster = CacheBuster.new)
+    def perform(reaction_id, cache_buster = CacheBuster)
       reaction = Reaction.find_by(id: reaction_id)
       return unless reaction&.reactable
 
@@ -11,7 +11,7 @@ module Reactions
         cache_buster.bust "/reactions?article_id=#{reaction.reactable_id}"
       elsif reaction.reactable_type == "Comment"
         path = "/reactions?commentable_id=#{reaction.reactable.commentable_id}&commentable_type=#{reaction.reactable.commentable_type}"
-        cache_buster.bust path
+        cache_buster.bust(path)
       end
     end
   end

app/jobs/tags/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Tags
   class BustCacheJob < ApplicationJob
     queue_as :tags_bust_cache
 
-    def perform(name, cache_buster = CacheBuster.new)
+    def perform(name, cache_buster = CacheBuster)
       cache_buster.bust_tag(name)
     end
   end

app/jobs/users/bust_cache_job.rb

@@ -2,7 +2,7 @@ module Users
   class BustCacheJob < ApplicationJob
     queue_as :users_bust_cache
 
-    def perform(user_id, cache_buster = CacheBuster.new)
+    def perform(user_id, cache_buster = CacheBuster)
       user = User.find_by(id: user_id)
       return unless user
 

app/labor/cache_buster.rb

@@ -1,9 +1,12 @@
-class CacheBuster
+module CacheBuster
   TIMEFRAMES = [
-    [1.week.ago, "week"], [1.month.ago, "month"], [1.year.ago, "year"], [5.years.ago, "infinity"]
+    [1.week.ago, "week"],
+    [1.month.ago, "month"],
+    [1.year.ago, "year"],
+    [5.years.ago, "infinity"],
   ].freeze
 
-  def bust(path)
+  def self.bust(path)
     return unless Rails.env.production?
 
     HTTParty.post("https://api.fastly.com/purge/https://dev.to#{path}",
@@ -14,7 +17,7 @@ class CacheBuster
     Rails.logger.error("Trying to bust cache of an invalid uri: #{e}")
   end
 
-  def bust_comment(commentable)
+  def self.bust_comment(commentable)
     return unless commentable
 
     bust_article_comment(commentable) if commentable.is_a?(Article)
@@ -24,20 +27,20 @@ class CacheBuster
     bust(commentable.path.to_s)
     commentable.comments.includes(:user).find_each do |comment|
       bust(comment.path)
-      bust(comment.path + "?i=i")
+      bust("#{comment.path}?i=i")
     end
     bust("#{commentable.path}/comments/*")
   end
 
-  def bust_article(article)
-    bust("/" + article.user.username)
+  def self.bust_article(article)
     bust(article.path)
-    bust(article.path + "/")
-    bust(article.path + "?i=i")
-    bust(article.path + "/?i=i")
-    bust(article.path + "/comments")
-    bust(article.path + "?preview=" + article.password)
-    bust(article.path + "?preview=" + article.password + "&i=i")
+    bust("/#{article.user.username}")
+    bust("#{article.path}/")
+    bust("#{article.path}?i=i")
+    bust("#{article.path}/?i=i")
+    bust("#{article.path}/comments")
+    bust("#{article.path}?preview=#{article.password}")
+    bust("#{article.path}?preview=#{article.password}&i=i")
     bust("/#{article.organization.slug}") if article.organization.present?
     bust_home_pages(article)
     bust_tag_pages(article)
@@ -49,21 +52,21 @@ class CacheBuster
     end
   end
 
-  def bust_home_pages(article)
+  def self.bust_home_pages(article)
     if article.featured_number.to_i > Time.current.to_i
       bust("/")
       bust("?i=i")
     end
     if article.video.present? && article.featured_number.to_i > 10.days.ago.to_i
-      CacheBuster.new.bust "/videos"
-      CacheBuster.new.bust "/videos?i=i"
+      bust("/videos")
+      bust("/videos?i=i")
     end
-    TIMEFRAMES.each do |timeframe|
-      if Article.published.where("published_at > ?", timeframe[0]).
+    TIMEFRAMES.each do |timestamp, interval|
+      if Article.published.where("published_at > ?", timestamp).
           order("positive_reactions_count DESC").limit(3).pluck(:id).include?(article.id)
-        bust("/top/#{timeframe[1]}")
-        bust("/top/#{timeframe[1]}?i=i")
-        bust("/top/#{timeframe[1]}/?i=i")
+        bust("/top/#{interval}")
+        bust("/top/#{interval}?i=i")
+        bust("/top/#{interval}/?i=i")
       end
     end
     if article.published && article.published_at > 1.hour.ago
@@ -73,7 +76,7 @@ class CacheBuster
     bust("/") if Article.published.order("hotness_score DESC").limit(4).pluck(:id).include?(article.id)
   end
 
-  def bust_tag_pages(article)
+  def self.bust_tag_pages(article)
     return unless article.published
 
     article.tag_list.each do |tag|
@@ -81,12 +84,12 @@ class CacheBuster
         bust("/t/#{tag}/latest")
         bust("/t/#{tag}/latest?i=i")
       end
-      TIMEFRAMES.each do |timeframe|
-        if Article.published.where("published_at > ?", timeframe[0]).tagged_with(tag).
+      TIMEFRAMES.each do |timestamp, interval|
+        if Article.published.where("published_at > ?", timestamp).tagged_with(tag).
             order("positive_reactions_count DESC").limit(3).pluck(:id).include?(article.id)
-          bust("/top/#{timeframe[1]}")
-          bust("/top/#{timeframe[1]}?i=i")
-          bust("/top/#{timeframe[1]}/?i=i")
+          bust("/top/#{interval}")
+          bust("/top/#{interval}?i=i")
+          bust("/top/#{interval}/?i=i")
           12.times do |i|
             bust("/api/articles?tag=#{tag}&top=#{i}")
           end
@@ -101,14 +104,14 @@ class CacheBuster
     end
   end
 
-  def bust_page(slug)
+  def self.bust_page(slug)
     bust "/page/#{slug}"
     bust "/page/#{slug}?i=i"
     bust "/#{slug}"
     bust "/#{slug}?i=i"
   end
 
-  def bust_tag(name)
+  def self.bust_tag(name)
     bust("/t/#{name}")
     bust("/t/#{name}?i=i")
     bust("/t/#{name}/?i=i")
@@ -116,16 +119,16 @@ class CacheBuster
     bust("/tags")
   end
 
-  def bust_events
+  def self.bust_events
     bust("/events")
     bust("/events?i=i")
   end
 
-  def bust_podcast(path)
+  def self.bust_podcast(path)
     bust("/" + path)
   end
 
-  def bust_organization(organization, slug)
+  def self.bust_organization(organization, slug)
     bust("/#{slug}")
     begin
       organization.articles.find_each do |article|
@@ -136,7 +139,7 @@ class CacheBuster
     end
   end
 
-  def bust_podcast_episode(podcast_episode, path, podcast_slug)
+  def self.bust_podcast_episode(podcast_episode, path, podcast_slug)
     podcast_episode.purge
     podcast_episode.purge_all
     begin
@@ -151,7 +154,7 @@ class CacheBuster
     podcast_episode.purge_all
   end
 
-  def bust_classified_listings(classified_listing)
+  def self.bust_classified_listings(classified_listing)
     bust("/listings")
     bust("/listings?i=i")
     bust("/listings/#{classified_listing.category}/#{classified_listing.slug}")
@@ -159,7 +162,7 @@ class CacheBuster
     bust("/listings/#{classified_listing.category}")
   end
 
-  def bust_user(user)
+  def self.bust_user(user)
     username = user.username
     paths = [
       "/#{username}", "/#{username}?i=i",
@@ -172,7 +175,7 @@ class CacheBuster
   end
 
   # bust commentable if it's an article
-  def bust_article_comment(commentable)
+  def self.bust_article_comment(commentable)
     bust("/") if Article.published.order("hotness_score DESC").limit(3).pluck(:id).include?(commentable.id)
     if commentable.decorate.cached_tag_list_array.include?("discuss") &&
         commentable.featured_number.to_i > 35.hours.ago.to_i

app/models/article.rb

@@ -618,10 +618,9 @@ class Article < ApplicationRecord
   def bust_cache
     return unless Rails.env.production?
 
-    cache_buster = CacheBuster.new
-    cache_buster.bust(path)
-    cache_buster.bust(path + "?i=i")
-    cache_buster.bust(path + "?preview=" + password)
+    CacheBuster.bust(path)
+    CacheBuster.bust("#{path}?i=i")
+    CacheBuster.bust("#{path}?preview=#{password}")
     async_bust
   end
 

app/models/badge.rb

@@ -23,8 +23,7 @@ class Badge < ApplicationRecord
   end
 
   def bust_path
-    cache_buster = CacheBuster.new
-    cache_buster.bust path
-    cache_buster.bust path + "?i=i"
+    CacheBuster.bust(path)
+    CacheBuster.bust("#{path}?i=i")
   end
 end

app/models/comment.rb

@@ -279,8 +279,7 @@ class Comment < ApplicationRecord
   def synchronous_bust
     commentable.touch(:last_comment_at) if commentable.respond_to?(:last_comment_at)
     user.touch(:last_comment_at)
-    cache_buster = CacheBuster.new
-    cache_buster.bust(commentable.path.to_s) if commentable
+    CacheBuster.bust(commentable.path.to_s) if commentable
     expire_root_fragment
   end
 

app/models/github_repo.rb

@@ -47,9 +47,8 @@ class GithubRepo < ApplicationRecord
     return if user.blank?
 
     user.touch
-    cache_buster = CacheBuster.new
-    cache_buster.bust user.path
-    cache_buster.bust user.path + "?i=i"
-    cache_buster.bust user.path + "/?i=i"
+    CacheBuster.bust(user.path)
+    CacheBuster.bust("#{user.path}?i=i")
+    CacheBuster.bust("#{user.path}/?i=i")
   end
 end

app/models/reaction.rb

@@ -79,7 +79,7 @@ class Reaction < ApplicationRecord
   private
 
   def cache_buster
-    @cache_buster ||= CacheBuster.new
+    CacheBuster
   end
 
   def touch_user

app/models/user.rb

@@ -408,11 +408,10 @@ class User < ApplicationRecord
   end
 
   def resave_articles
-    cache_buster = CacheBuster.new
     articles.find_each do |article|
       if article.path
-        cache_buster.bust(article.path)
-        cache_buster.bust(article.path + "?i=i")
+        CacheBuster.bust(article.path)
+        CacheBuster.bust("#{article.path}?i=i")
       end
       article.save
     end

app/services/edge_cache/commentable/bust.rb

@@ -1,7 +1,7 @@
 module EdgeCache
   module Commentable
     class Bust
-      def initialize(commentable, cache_buster = CacheBuster.new)
+      def initialize(commentable, cache_buster = CacheBuster)
         @commentable = commentable
         @cache_buster = cache_buster
       end

app/services/moderator/banish_user.rb

@@ -32,7 +32,7 @@ module Moderator
         new_username = "spam_#{rand(1_000_000)}"
       end
       user.update_columns(name: new_name, username: new_username, old_username: user.username, profile_updated_at: Time.current)
-      CacheBuster.new.bust("/#{user.old_username}")
+      CacheBuster.bust("/#{user.old_username}")
     end
 
     def remove_profile_info

app/services/moderator/delete_user.rb

@@ -21,7 +21,7 @@ module Moderator
       reassign_articles
       reassign_comments
       delete_non_content_activity_and_user
-      CacheBuster.new.bust("/ghost")
+      CacheBuster.bust("/ghost")
     end
 
     private
@@ -29,7 +29,7 @@ module Moderator
     def delete_non_content_activity_and_user
       delete_user_activity
       user.unsubscribe_from_newsletters
-      CacheBuster.new.bust("/#{user.username}")
+      CacheBuster.bust("/#{user.username}")
       user.delete
     end
 

app/services/moderator/merge_user.rb

@@ -25,7 +25,7 @@ module Moderator
       @delete_user.delete
       @keep_user.touch(:profile_updated_at)
 
-      CacheBuster.new.bust "/#{@keep_user.username}"
+      CacheBuster.bust("/#{@keep_user.username}")
     end
 
     private

app/services/users/delete.rb

@@ -9,7 +9,7 @@ module Users
       delete_articles
       delete_user_activity
       user.unsubscribe_from_newsletters
-      CacheBuster.new.bust("/#{user.username}")
+      CacheBuster.bust("/#{user.username}")
       user.delete
     end
 

app/services/users/delete_articles.rb

@@ -2,7 +2,7 @@ module Users
   module DeleteArticles
     module_function
 
-    def call(user, cache_buster = CacheBuster.new)
+    def call(user, cache_buster = CacheBuster)
       return unless user.articles.any?
 
       virtual_articles = user.articles.map { |article| Article.new(article.attributes) }

app/services/users/delete_comments.rb

@@ -2,7 +2,7 @@ module Users
   module DeleteComments
     module_function
 
-    def call(user, cache_buster = CacheBuster.new)
+    def call(user, cache_buster = CacheBuster)
       return unless user.comments.any?
 
       user.comments.find_each do |comment|

lib/tasks/fetch.rake

@@ -7,14 +7,13 @@ task get_podcast_episodes: :environment do
 end
 
 task periodic_cache_bust: :environment do
-  cache_buster = CacheBuster.new
-  cache_buster.bust("/feed.xml")
-  cache_buster.bust("/badge")
-  cache_buster.bust("/shecoded")
+  CacheBuster.bust("/feed.xml")
+  CacheBuster.bust("/badge")
+  CacheBuster.bust("/shecoded")
 end
 
 task hourly_bust: :environment do
-  CacheBuster.new.bust("/")
+  CacheBuster.bust("/")
 end
 
 task fetch_all_rss: :environment do

spec/jobs/events/bust_cache_job_spec.rb

@@ -1,10 +1,9 @@
 require "rails_helper"
 
 RSpec.describe Events::BustCacheJob do
-  let(:cache_buster) { instance_double(CacheBuster) }
+  let(:cache_buster) { class_double(CacheBuster) }
 
   before do
-    allow(CacheBuster).to receive(:new).and_return(cache_buster)
     allow(cache_buster).to receive(:bust_events)
   end
 

spec/jobs/organizations/bust_cache_job_spec.rb

@@ -5,10 +5,9 @@ RSpec.describe Organizations::BustCacheJob, type: :job do
 
   describe "#perform_now" do
     let!(:organization) { FactoryBot.create(:organization) }
-    let(:cache_buster) { instance_double(CacheBuster) }
+    let(:cache_buster) { class_double(CacheBuster) }
 
     before do
-      allow(CacheBuster).to receive(:new).and_return(cache_buster)
       allow(cache_buster).to receive(:bust_organization)
     end
 

spec/jobs/pages/bust_cache_job_spec.rb

@@ -1,10 +1,9 @@
 require "rails_helper"
 
 RSpec.describe Pages::BustCacheJob do
-  let(:cache_buster) { instance_double(CacheBuster) }
+  let(:cache_buster) { class_double(CacheBuster) }
 
   before do
-    allow(CacheBuster).to receive(:new).and_return(cache_buster)
     allow(cache_buster).to receive(:bust_page)
   end
 

spec/jobs/podcast_episodes/bust_cache_job_spec.rb

@@ -6,10 +6,9 @@ RSpec.describe PodcastEpisodes::BustCacheJob do
   describe "#perform_now" do
     let!(:podcast) { create(:podcast) }
     let!(:podcast_episode) { FactoryBot.create(:podcast_episode, podcast_id: podcast.id) }
-    let(:cache_buster) { instance_double(CacheBuster) }
+    let(:cache_buster) { class_double(CacheBuster) }
 
     before do
-      allow(CacheBuster).to receive(:new).and_return(cache_buster)
       allow(cache_buster).to receive(:bust_podcast_episode)
     end
 

spec/jobs/podcasts/bust_cache_job_spec.rb

@@ -1,10 +1,9 @@
 require "rails_helper"
 
 RSpec.describe Podcasts::BustCacheJob do
-  let(:cache_buster) { instance_double(CacheBuster) }
+  let(:cache_buster) { class_double(CacheBuster) }
 
   before do
-    allow(CacheBuster).to receive(:new).and_return(cache_buster)
     allow(cache_buster).to receive(:bust_podcast)
   end
 

spec/jobs/tags/bust_cache_job_spec.rb

@@ -1,10 +1,9 @@
 require "rails_helper"
 
 RSpec.describe Tags::BustCacheJob do
-  let(:cache_buster) { instance_double(CacheBuster) }
+  let(:cache_buster) { class_double(CacheBuster) }
 
   before do
-    allow(CacheBuster).to receive(:new).and_return(cache_buster)
     allow(cache_buster).to receive(:bust_tag)
   end
 

spec/labor/cache_buster_spec.rb

@@ -1,7 +1,7 @@
 require "rails_helper"
 
 RSpec.describe CacheBuster do
-  let(:cache_buster) { described_class.new }
+  let(:cache_buster) { described_class }
   let(:user) { create(:user) }
   let(:article) { create(:article, user_id: user.id) }
   let(:comment) { create(:comment, user_id: user.id, commentable_id: article.id) }
@@ -79,7 +79,6 @@ RSpec.describe CacheBuster do
 
     it "logs an error from bust_podcast_episode" do
       allow(Rails.logger).to receive(:warn)
-      allow(described_class).to receive(:new).and_return(cache_buster)
       allow(cache_buster).to receive(:bust).and_raise(StandardError)
       cache_buster.bust_podcast_episode(podcast_episode, 12, "-007")
       expect(Rails.logger).to have_received(:warn).once

spec/requests/internal/classified_listings_spec.rb

@@ -4,11 +4,9 @@ RSpec.describe "/internal/listings", type: :request do
   describe "PUT /internal/listings/:id" do
     let(:admin) { create(:user, :super_admin) }
     let(:classified_listing) { create(:classified_listing, user_id: admin.id) }
-    let(:cache_buster) { instance_double(CacheBuster) }
 
     before do
-      allow(CacheBuster).to receive(:new).and_return(cache_buster)
-      allow(cache_buster).to receive(:bust_classified_listings)
+      allow(CacheBuster).to receive(:bust_classified_listings)
       sign_in admin
     end
 
@@ -16,7 +14,7 @@ RSpec.describe "/internal/listings", type: :request do
       put "/internal/listings/#{classified_listing.id}", params: {
         classified_listing: { title: "updated" }
       }
-      expect(cache_buster).to have_received(:bust_classified_listings)
+      expect(CacheBuster).to have_received(:bust_classified_listings)
     end
   end
 end

spec/services/users/delete_spec.rb

@@ -9,11 +9,9 @@ RSpec.describe Users::Delete, type: :service do
   end
 
   it "busts user profile page" do
-    buster = double
-    allow(buster).to receive(:bust)
-    allow(CacheBuster).to receive(:new).and_return(buster)
+    allow(CacheBuster).to receive(:bust)
     described_class.new(user).call
-    expect(buster).to have_received(:bust).with("/#{user.username}")
+    expect(CacheBuster).to have_received(:bust).with("/#{user.username}")
   end
 
   it "deletes user's follows" do