Dispatch events to the webhook endpoints #3715 (#3872)

* Start with webhooks: table and model

* Start with webhooks api

* Start with webhooks api

* Webhook::Event class and events list

* Remove commented callbacks

* Start with sending events to webhook endpoints

* A couple of tests for Articles::Creator

* Send event to webhook endpoint on article destroy

* Dispatch event on article update

* Dispatch event when an article updated from admin

* Spec for the webhook job

* One more test for the dispatch event job

* Integration-like spec for event dispatching to webhook endpoints when creating an article

* Use Addressable::URI to parse endpoint url

* Add oj as a faster fast_jsonapi backend

* Renamed serializers

* Move article serialization out of a model

* Don't allow to create a webhook event with invalid type

* Add fields for ArticleSerializer

* Fix webhook event job specs

* Specify timeout when dispatching events

* Fix webhook job spec

* Change webhook events queue name

* Change serialized article fields for the dispatchable events

* Include user data when serializing an article for webhook event

* Moved decorating out of Webhook::DispatchEvent, fixed most specs

* Fix route in ArticleSerializer

* Move Article decoration to Webhook::PayloadAdapter

* Refactor image url helpers to avoid including helpers into serializer

* Fix specs

* Default url options for production

Gemfile

@@ -38,6 +38,7 @@ gem "dry-struct", "~> 1.0" # Typed structs and value objects
 gem "email_validator", "~> 2.0" # Email validator for Rails and ActiveModel
 gem "emoji_regex", "~> 2.0" # A pair of Ruby regular expressions for matching Unicode Emoji symbols
 gem "envied", "~> 0.9" # Ensure presence and type of your app's ENV-variables
+gem "fast_jsonapi", "~> 1.5" # Serializer for Ruby objects
 gem "fastly", "~> 1.15" # Client library for the Fastly acceleration system
 gem "fastly-rails", "~> 0.8" # Fastly dynamic caching integration for Rails
 gem "feedjira", "~> 3.0" # A feed fetching and parsing library
@@ -57,6 +58,7 @@ gem "kaminari", "~> 1.1" # A Scope & Engine based, clean, powerful, customizable
 gem "liquid", "~> 4.0" # A secure, non-evaling end user template engine with aesthetic markup
 gem "nokogiri", "~> 1.10" # HTML, XML, SAX, and Reader parser
 gem "octokit", "~> 4.14" # Simple wrapper for the GitHub API
+gem "oj", "~> 3.9" # JSON parser and object serializer
 gem "omniauth", "~> 1.9" # A generalized Rack framework for multiple-provider authentication
 gem "omniauth-github", "~> 1.3" # OmniAuth strategy for GitHub
 gem "omniauth-twitter", "~> 1.4" # OmniAuth strategy for Twitter

Gemfile.lock

@@ -323,6 +323,8 @@ GEM
       multipart-post (>= 1.2, < 3)
     faraday_middleware (0.13.1)
       faraday (>= 0.7.4, < 1.0)
+    fast_jsonapi (1.5)
+      activesupport (>= 4.2)
     fastimage (2.1.1)
     fastly (1.15.0)
     fastly-rails (0.8.0)
@@ -511,6 +513,7 @@ GEM
       rack (>= 1.2, < 3)
     octokit (4.14.0)
       sawyer (~> 0.8.0, >= 0.5.3)
+    oj (3.9.1)
     omniauth (1.9.0)
       hashie (>= 3.4.6, < 3.7.0)
       rack (>= 1.6.2, < 3)
@@ -884,6 +887,7 @@ DEPENDENCIES
   erb_lint (~> 0.0)
   factory_bot_rails (~> 4.11)
   faker (~> 2.2)
+  fast_jsonapi (~> 1.5)
   fastly (~> 1.15)
   fastly-rails (~> 0.8)
   feedjira (~> 3.0)
@@ -911,6 +915,7 @@ DEPENDENCIES
   nakayoshi_fork (~> 0.0.4)
   nokogiri (~> 1.10)
   octokit (~> 4.14)
+  oj (~> 3.9)
   omniauth (~> 1.9)
   omniauth-github (~> 1.3)
   omniauth-twitter (~> 1.4)

app/controllers/admin/articles_controller.rb

@@ -17,6 +17,20 @@ module Admin
       end
     end
 
+    def update
+      if requested_resource.update(resource_params)
+        Webhook::DispatchEvent.call("article_updated", requested_resource)
+        redirect_to(
+          [namespace, requested_resource],
+          notice: translate_with_resource("update.success"),
+        )
+      else
+        render :edit, locals: {
+          page: Administrate::Page::Form.new(dashboard, requested_resource)
+        }
+      end
+    end
+
     def destroy
       Articles::Destroyer.call(requested_resource)
       if requested_resource.destroyed?

app/controllers/articles_controller.rb

@@ -145,6 +145,7 @@ class ArticlesController < ApplicationController
                      end
     updated = @article.update(article_params_json.merge(edited_at: edited_at_date))
     handle_notifications(updated)
+    Webhook::DispatchEvent.call("article_updated", @article) if updated
     respond_to do |format|
       format.html do
         # TODO: JSON should probably not be returned in the format.html section

app/helpers/application_helper.rb

@@ -107,23 +107,7 @@ module ApplicationHelper
   end
 
   def cloud_cover_url(url)
-    return if url.blank?
-    return asset_path("triple-unicorn") if Rails.env.test?
-    return url if Rails.env.development?
-
-    width = 1000
-    height = 420
-    quality = "auto"
-
-    cl_image_path(url,
-                  type: "fetch",
-                  width: width,
-                  height: height,
-                  crop: "imagga_scale",
-                  quality: quality,
-                  flags: "progressive",
-                  fetch_format: "auto",
-                  sign_url: true)
+    CloudCoverUrl.new(url).call
   end
 
   def tag_colors(tag)

app/helpers/social_image_helper.rb

@@ -18,49 +18,10 @@ module SocialImageHelper
   end
 
   def article_social_image_url(article)
-    image = user_defined_image(article)
-    if image.present?
-      return cl_image_path(image,
-                           type: "fetch",
-                           width: "1000",
-                           height: "500",
-                           crop: "imagga_scale",
-                           quality: "auto",
-                           flags: "progressive",
-                           fetch_format: "auto",
-                           sign_url: true)
-    end
-    return legacy_article_social_image(article) unless use_new_social_url?(article)
-
-    article_social_preview_url(article, format: :png)
-  end
-
-  def legacy_article_social_image(article)
-    cache_key = "article-social-img-#{article}-#{article.updated_at}-#{article.comments_count}"
-
-    Rails.cache.fetch(cache_key, expires_in: 1.hour) do
-      src = GeneratedImage.new(article).social_image
-      return src if src.start_with? "https://res.cloudinary.com/"
-
-      cl_image_path(src,
-                    type: "fetch",
-                    width: "1000",
-                    height: "500",
-                    crop: "imagga_scale",
-                    quality: "auto",
-                    flags: "progressive",
-                    fetch_format: "auto",
-                    sign_url: true)
-    end
+    Articles::SocialImage.new(article).url
   end
 
   def use_new_social_url?(resource)
     resource.updated_at > SOCIAL_PREVIEW_MIGRATION_DATETIME
   end
-
-  def user_defined_image(article)
-    return article.social_image if article.social_image.present?
-    return article.main_image if article.main_image.present?
-    return article.video_thumbnail_url if article.video_thumbnail_url.present?
-  end
 end

app/jobs/webhook/dispatch_event_job.rb

@@ -0,0 +1,10 @@
+module Webhook
+  class DispatchEventJob < ApplicationJob
+    queue_as :webhook_dispatch_events
+
+    def perform(endpoint_url:, payload:, client: HTTParty)
+      uri = Addressable::URI.parse(endpoint_url)
+      client.post(uri, headers: { "Content-Type" => "application/json" }, body: payload, timeout: 10)
+    end
+  end
+end

app/models/webhook/event.rb

@@ -6,13 +6,20 @@ module Webhook
       article_destroyed
     ].freeze
 
-    def initialize(event_name, payload = {})
-      @event_name = event_name
+    attr_reader :event_type, :payload, :timestamp
+
+    def initialize(event_type:, payload: {})
+      raise InvalidEvent unless EVENT_TYPES.include?(event_type)
+
+      @event_type = event_type
       @payload = payload
+      @timestamp = Time.current.rfc3339
     end
 
-    private
-
-    attr_reader :event_name, :payload
+    def as_json(*_args)
+      Webhook::EventSerializer.new(self).serializable_hash
+    end
   end
+
+  class InvalidEvent < StandardError; end
 end

app/serializers/webhook/article_destroyed_serializer.rb

@@ -0,0 +1,7 @@
+module Webhook
+  class ArticleDestroyedSerializer
+    include FastJsonapi::ObjectSerializer
+    set_type :article
+    attributes :title
+  end
+end

app/serializers/webhook/article_serializer.rb

@@ -0,0 +1,36 @@
+module Webhook
+  class ArticleSerializer
+    include FastJsonapi::ObjectSerializer
+
+    set_type :article
+    attributes :title, :description, :readable_publish_date, :cached_tag_list, :cached_tag_list_array,
+               :slug, :path, :url, :comments_count, :positive_reactions_count, :body_markdown
+
+    attribute :canonical_url, &:processed_canonical_url
+    attribute :body_html, &:processed_html
+    attribute :created_at do |a|
+      a.created_at.utc.iso8601
+    end
+    attribute :edited_at do |a|
+      a.edited_at&.utc&.iso8601
+    end
+    attribute :crossposted_at do |a|
+      a.crossposted_at&.utc&.iso8601
+    end
+    attribute :published_at do |a|
+      a.published_at&.utc&.iso8601
+    end
+    attribute :last_comment_at do |a|
+      a.last_comment_at&.utc&.iso8601
+    end
+    attribute :cover_image do |a|
+      CloudCoverUrl.new(a.url).call
+    end
+    attribute :social_image do |article|
+      Articles::SocialImage.new(article).url
+    end
+    attribute :user do |a|
+      UserSerializer.new(a.user).serializable_hash
+    end
+  end
+end

app/serializers/webhook/event_serializer.rb

@@ -0,0 +1,10 @@
+module Webhook
+  class EventSerializer
+    include FastJsonapi::ObjectSerializer
+    set_type :webhook_event
+    set_id do |event|
+      "#{event.event_type}_#{event.timestamp}"
+    end
+    attributes :event_type, :timestamp, :payload
+  end
+end

app/serializers/webhook/user_serializer.rb

@@ -0,0 +1,14 @@
+module Webhook
+  class UserSerializer
+    include FastJsonapi::ObjectSerializer
+
+    attributes :name, :username, :twitter_username, :github_username
+    attribute :website_url, &:processed_website_url
+    attribute :profile_image do |user|
+      ProfileImage.new(user).get(640)
+    end
+    attribute :profile_image_90 do |user|
+      ProfileImage.new(user).get(90)
+    end
+  end
+end

app/services/articles/creator.rb

@@ -1,8 +1,9 @@
 module Articles
   class Creator
-    def initialize(user, article_params)
+    def initialize(user, article_params, event_dispatcher = Webhook::DispatchEvent)
       @user = user
       @article_params = article_params
+      @event_dispatcher = event_dispatcher
     end
 
     def self.call(*args)
@@ -12,8 +13,29 @@ module Articles
     def call
       raise if RateLimitChecker.new(user).limit_by_action("published_article_creation")
 
-      tags = article_params[:tags]
+      article = save_article
+
+      if article.persisted?
+        NotificationSubscription.create(user: user, notifiable_id: article.id, notifiable_type: "Article", config: "all_comments")
+        Notification.send_to_followers(article, "Published") if article.published
+
+        dispatch_event(article)
+      end
+
+      article.decorate
+    end
+
+    private
+
+    attr_reader :user, :article_params, :event_dispatcher
+
+    def dispatch_event(article)
+      event_dispatcher.call("article_created", article)
+    end
+
+    def save_article
       series = article_params[:series]
+      tags = article_params[:tags]
 
       # convert tags from array to a string
       if tags.present?
@@ -25,15 +47,8 @@ module Articles
       article.user_id = user.id
       article.show_comments = true
       article.collection = Collection.find_series(series, user) if series.present?
-      if article.save
-        NotificationSubscription.create(user: user, notifiable_id: article.id, notifiable_type: "Article", config: "all_comments")
-        Notification.send_to_followers(article, "Published") if article.published
-      end
-      article.decorate
+      article.save
+      article
     end
-
-    private
-
-    attr_reader :user, :article_params
   end
 end

app/services/articles/destroyer.rb

@@ -2,10 +2,11 @@ module Articles
   module Destroyer
     module_function
 
-    def call(article)
+    def call(article, event_dispatcher = Webhook::DispatchEvent)
       article.destroy!
       Notification.remove_all_without_delay(notifiable_id: article.id, notifiable_type: "Article", action: "Published")
       Notification.remove_all(notifiable_id: article.id, notifiable_type: "Article", action: "Reaction")
+      event_dispatcher.call("article_destroyed", article)
     end
   end
 end

app/services/articles/updater.rb

@@ -1,9 +1,10 @@
 module Articles
   class Updater
-    def initialize(user, article_id, article_params)
+    def initialize(user, article_id, article_params, event_dispatcher = Webhook::DispatchEvent)
       @user = user
       @article_id = article_id
       @article_params = article_params
+      @event_dispatcher = event_dispatcher
     end
 
     def self.call(*args)
@@ -37,13 +38,18 @@ module Articles
       send_notification = article.published && article.saved_change_to_published_at.present?
       Notification.send_to_followers(article, "Published") if send_notification
 
+      dispatch_event(article)
+
       article.decorate
     end
 
     private
 
-    attr_reader :user, :article_id
-    attr_accessor :article_params
+    attr_reader :user, :article_id, :article_params, :event_dispatcher
+
+    def dispatch_event(article)
+      event_dispatcher.call("article_updated", article)
+    end
 
     def load_article
       relation = user.has_role?(:super_admin) ? Article.includes(:user) : user.articles

app/services/webhook/dispatch_event.rb

@@ -0,0 +1,26 @@
+module Webhook
+  class DispatchEvent
+    def initialize(event_type, record)
+      @event_type = event_type
+      @record = record
+    end
+
+    def self.call(*args)
+      new(*args).call
+    end
+
+    def call
+      endpoint_urls = Endpoint.for_events([event_type]).pluck(:target_url)
+      return if endpoint_urls.empty?
+
+      event_json = Event.new(event_type: event_type, payload: PayloadAdapter.new(record).hash).to_json
+      endpoint_urls.each do |url|
+        DispatchEventJob.perform_later(endpoint_url: url, payload: event_json)
+      end
+    end
+
+    private
+
+    attr_reader :event_type, :record
+  end
+end

app/services/webhook/payload_adapter.rb

@@ -0,0 +1,30 @@
+module Webhook
+  class PayloadAdapter
+    def initialize(object)
+      raise InvalidPayloadObject unless object.is_a?(Article)
+
+      @object = object
+    end
+
+    def hash
+      serializer.new(prepared_object).serializable_hash
+    end
+
+    private
+
+    attr_reader :object
+
+    # decorate article before serializing
+    def prepared_object
+      return object unless object.is_a?(Article) && !object.decorated?
+
+      object.decorate
+    end
+
+    def serializer
+      object.destroyed? ? ArticleDestroyedSerializer : ArticleSerializer
+    end
+  end
+
+  class InvalidPayloadObject < StandardError; end
+end

app/view_objects/articles/social_image.rb

@@ -0,0 +1,63 @@
+module Articles
+  class SocialImage
+    include Rails.application.routes.url_helpers
+    include CloudinaryHelper
+
+    def initialize(article)
+      @article = article
+    end
+
+    SOCIAL_PREVIEW_MIGRATION_DATETIME = Time.zone.parse("2019-04-22T00:00:00Z")
+
+    def url
+      image = user_defined_image
+      if image.present?
+        return cl_image_path(image,
+                             type: "fetch",
+                             width: "1000",
+                             height: "500",
+                             crop: "imagga_scale",
+                             quality: "auto",
+                             flags: "progressive",
+                             fetch_format: "auto",
+                             sign_url: true)
+      end
+      return legacy_article_social_image unless use_new_social_url?
+
+      article_social_preview_url(article, format: :png)
+    end
+
+    private
+
+    attr_reader :article
+
+    def legacy_article_social_image
+      cache_key = "article-social-img-#{article}-#{article.updated_at}-#{article.comments_count}"
+
+      Rails.cache.fetch(cache_key, expires_in: 1.hour) do
+        src = GeneratedImage.new(article).social_image
+        return src if src.start_with? "https://res.cloudinary.com/"
+
+        cl_image_path(src,
+                      type: "fetch",
+                      width: "1000",
+                      height: "500",
+                      crop: "imagga_scale",
+                      quality: "auto",
+                      flags: "progressive",
+                      fetch_format: "auto",
+                      sign_url: true)
+      end
+    end
+
+    def use_new_social_url?
+      article.updated_at > SOCIAL_PREVIEW_MIGRATION_DATETIME
+    end
+
+    def user_defined_image
+      return article.social_image if article.social_image.present?
+      return article.main_image if article.main_image.present?
+      return article.video_thumbnail_url if article.video_thumbnail_url.present?
+    end
+  end
+end

app/view_objects/cloud_cover_url.rb

@@ -0,0 +1,31 @@
+class CloudCoverUrl
+  include CloudinaryHelper
+  include ActionView::Helpers::AssetUrlHelper
+
+  def initialize(url)
+    @url = url
+  end
+
+  def call
+    return if url.blank?
+    return url if Rails.env.development? || Rails.env.test?
+
+    width = 1000
+    height = 420
+    quality = "auto"
+
+    cl_image_path(url,
+                  type: "fetch",
+                  width: width,
+                  height: height,
+                  crop: "imagga_scale",
+                  quality: quality,
+                  flags: "progressive",
+                  fetch_format: "auto",
+                  sign_url: true)
+  end
+
+  private
+
+  attr_reader :url
+end

config/application.rb

@@ -43,6 +43,7 @@ module PracticalDeveloper
     config.autoload_paths += Dir["#{config.root}/app/sanitizers"]
     config.autoload_paths += Dir["#{config.root}/app/facades"]
     config.autoload_paths += Dir["#{config.root}/app/errors"]
+    config.autoload_paths += Dir["#{config.root}/app/view_objects"]
     config.autoload_paths += Dir["#{config.root}/lib/"]
 
     config.active_record.observers = :article_observer, :reaction_observer, :comment_observer

config/environments/development.rb

@@ -107,3 +107,5 @@ Rails.application.configure do
     Bullet.rails_logger = true
   end
 end
+
+Rails.application.routes.default_url_options = { host: Rails.application.config.app_domain }

config/environments/production.rb

@@ -125,3 +125,5 @@ Rails.application.configure do
   config.middleware.use Rack::HostRedirect,
                         "practicaldev.herokuapp.com" => "dev.to"
 end
+
+Rails.application.routes.default_url_options = { host: Rails.application.config.app_domain }

config/environments/test.rb

@@ -68,3 +68,5 @@ Rails.application.configure do
     Bullet.add_whitelist(type: :n_plus_one_query, class_name: "ActsAsTaggableOn::Tagging", association: :tag)
   end
 end
+
+Rails.application.routes.default_url_options = { host: "test.host" }

spec/jobs/webhook/dispatch_event_job_spec.rb

@@ -0,0 +1,27 @@
+require "rails_helper"
+
+RSpec.describe Webhook::DispatchEventJob, type: :job do
+  include_examples "#enqueues_job", "webhook_dispatch_events", "https://example.com", ""
+
+  describe "#perform_now" do
+    let(:article) { create(:article) }
+    let(:payload) { Webhook::PayloadAdapter.new(article).hash }
+    let(:json) { Webhook::Event.new(event_type: "article_updated", payload: payload).to_json }
+    let(:url) { Faker::Internet.url }
+
+    it "posts an event" do
+      client = double
+      allow(client).to receive(:post)
+      described_class.perform_now(endpoint_url: url, payload: json, client: client)
+      expect(client).to have_received(:post).once.
+        with(Addressable::URI.parse(url), headers: { "Content-Type" => "application/json" },
+                                          body: json,
+                                          timeout: 10)
+    end
+
+    it "doesn't fail" do
+      stub_request(:post, url).to_return(status: 200)
+      described_class.perform_now(endpoint_url: url, payload: json)
+    end
+  end
+end

spec/models/webhook/event_spec.rb

@@ -0,0 +1,45 @@
+require "rails_helper"
+
+RSpec.describe Webhook::Event, type: :model do
+  let(:article) { create(:article) }
+  let!(:payload) { Webhook::PayloadAdapter.new(article).hash }
+
+  it "rases an exception" do
+    expect do
+      described_class.new(event_type: "cool_event")
+    end.to raise_error(Webhook::InvalidEvent)
+  end
+
+  describe "#as_json" do
+    it "provides correct json (sample)" do
+      event = described_class.new(event_type: "article_created", payload: { title: "Hello, world" })
+      hash = event.as_json
+
+      attributes = hash[:data][:attributes]
+
+      expect(attributes[:event_type]).to eq("article_created")
+      expect(attributes[:timestamp]).to be_truthy
+      expect(attributes[:payload][:title]).to eq("Hello, world")
+    end
+
+    it "provides correct json including article" do
+      event = described_class.new(event_type: "article_updated", payload: payload)
+      hash = event.as_json
+      attributes = hash[:data][:attributes]
+      expect(attributes[:event_type]).to eq("article_updated")
+      expect(attributes[:payload][:data][:attributes][:title]).to eq(article.title)
+    end
+  end
+
+  describe "#to_json" do
+    it "provides correct json including article" do
+      event = described_class.new(event_type: "article_updated", payload: payload)
+      json = event.to_json
+      hash = JSON.parse(json)
+      attributes = hash["data"]["attributes"]
+
+      expect(attributes["event_type"]).to eq("article_updated")
+      expect(attributes["payload"]["data"]["attributes"]["title"]).to eq(article.title)
+    end
+  end
+end

spec/requests/articles/articles_create_spec.rb

@@ -47,4 +47,33 @@ RSpec.describe "ArticlesCreate", type: :request do
     }
     expect(Collection.last.slug).to eq("helloyo")
   end
+
+  context "when scheduling jobs" do
+    let(:url) { Faker::Internet.url(scheme: "https") }
+    let(:article_params) do
+      {
+        article: {
+          title: "NEW TITLE #{rand(100)}",
+          body_markdown: "---\ntitle: hey hey hahuu\npublished: false\nseries: helloyo\n---\nYo ho ho#{rand(100)}"
+        }
+      }
+    end
+
+    before do
+      create(:webhook_endpoint, events: %w[article_created article_updated], target_url: url)
+    end
+
+    it "schedules a dispatching event job" do
+      expect do
+        post "/articles", params: article_params
+      end.to have_enqueued_job(Webhook::DispatchEventJob).once
+    end
+
+    it "doesn't fail when executing jobs" do
+      stub_request(:post, url).to_return(status: 200)
+      perform_enqueued_jobs do
+        post "/articles", params: article_params
+      end
+    end
+  end
 end

spec/requests/articles/articles_update_spec.rb

@@ -108,4 +108,13 @@ RSpec.describe "ArticlesUpdate", type: :request do
     expect(response).to redirect_to "#{article.path}/edit"
     expect(article.reload.video_thumbnail_url).to include "https://i.imgur.com/HPiu7N4.jpg"
   end
+
+  it "schedules a dispatching event job" do
+    create(:webhook_endpoint, events: %w[article_created article_updated])
+    expect do
+      put "/articles/#{article.id}", params: {
+        article: { title: "new_title", body_markdown: "Yo ho ho#{rand(100)}", tag_list: "yo" }
+      }
+    end.to have_enqueued_job(Webhook::DispatchEventJob).once
+  end
 end

spec/services/articles/creator_spec.rb

@@ -30,6 +30,13 @@ RSpec.describe Articles::Creator do
         described_class.call(user, valid_attributes)
       end.to change(NotificationSubscription, :count).by(1)
     end
+
+    it "calls an event dispatcher" do
+      event_dispatcher = double
+      allow(event_dispatcher).to receive(:call)
+      article = described_class.call(user, valid_attributes, event_dispatcher)
+      expect(event_dispatcher).to have_received(:call).with("article_created", article.object)
+    end
   end
 
   context "when valid attributes" do
@@ -63,5 +70,12 @@ RSpec.describe Articles::Creator do
         described_class.call(user, invalid_attributes)
       end.not_to change(NotificationSubscription, :count)
     end
+
+    it "doesn't call an event dispatcher" do
+      event_dispatcher = double
+      allow(event_dispatcher).to receive(:call)
+      described_class.call(user, invalid_attributes, event_dispatcher)
+      expect(event_dispatcher).not_to have_received(:call)
+    end
   end
 end

spec/services/articles/destroyer_spec.rb

@@ -0,0 +1,23 @@
+require "rails_helper"
+
+RSpec.describe Articles::Destroyer do
+  let(:article) { create(:article) }
+
+  it "destroys an article" do
+    described_class.call(article)
+    expect(Article.find_by(id: article.id)).to be_nil
+  end
+
+  it "schedules removing notifications" do
+    expect do
+      described_class.call(article)
+    end.to have_enqueued_job(Notifications::RemoveAllJob).once
+  end
+
+  it "calls events dispatcher" do
+    event_dispatcher = double
+    allow(event_dispatcher).to receive(:call)
+    described_class.call(article, event_dispatcher)
+    expect(event_dispatcher).to have_received(:call).with("article_destroyed", article)
+  end
+end

spec/services/articles/updater_spec.rb

@@ -0,0 +1,20 @@
+require "rails_helper"
+
+RSpec.describe Articles::Updater do
+  let(:user) { create(:user) }
+  let!(:article) { create(:article, user: user) }
+  let(:attributes) { { body_markdown: "sample" } }
+
+  it "updates an article" do
+    described_class.call(user, article.id, attributes)
+    article.reload
+    expect(article.body_markdown).to eq("sample")
+  end
+
+  it "calls events dispatcher" do
+    event_dispatcher = double
+    allow(event_dispatcher).to receive(:call)
+    described_class.call(user, article.id, attributes, event_dispatcher)
+    expect(event_dispatcher).to have_received(:call).with("article_updated", article)
+  end
+end

spec/services/webhook/dispatch_event_spec.rb

@@ -0,0 +1,21 @@
+require "rails_helper"
+
+RSpec.describe Webhook::DispatchEvent, type: :service do
+  let!(:article) { create(:article) }
+
+  it "does nothing if there are no corresponding endpoints" do
+    create(:webhook_endpoint, events: %w[article_created])
+    expect do
+      described_class.call("article_destroyed", article)
+    end.not_to have_enqueued_job(Webhook::DispatchEventJob)
+  end
+
+  it "schedules jobs" do
+    create(:webhook_endpoint, events: %w[article_created], target_url: "https://create-webhooks.example.com/accept")
+    create(:webhook_endpoint, events: %w[article_created article_updated article_destroyed], target_url: "https://all-webhooks.example.com/accept")
+    create(:webhook_endpoint, events: %w[article_destroyed], target_url: "https://destroy-webhooks.example.com/accept")
+    expect do
+      described_class.call("article_created", article)
+    end.to have_enqueued_job(Webhook::DispatchEventJob).twice
+  end
+end

spec/services/webhook/payload_adapter_spec.rb

@@ -0,0 +1,35 @@
+require "rails_helper"
+
+RSpec.describe Webhook::PayloadAdapter, type: :service do
+  it "raises an exception when invalid object is passed" do
+    expect do
+      described_class.new(User.new).hash
+    end.to raise_error(Webhook::InvalidPayloadObject)
+  end
+
+  describe "#hash" do
+    let(:user) { create(:user) }
+    let!(:article) { create(:article, title: "I'm super", user: user) }
+
+    it "returns a hash for a persisted article" do
+      data = described_class.new(article).hash
+      expect(data).to be_kind_of(Hash)
+      expect(data[:data][:attributes][:title]).to eq(article.title)
+      expect(data[:data][:attributes][:body_markdown]).to be_truthy
+    end
+
+    it "returns a hash with a user" do
+      data = described_class.new(article).hash
+      expect(data[:data][:attributes][:user][:data][:attributes][:username]).to eq(user.username)
+    end
+
+    it "returns a hash for a destroyed article" do
+      article = create(:article, title: "hello")
+      article.destroy
+      data = described_class.new(article).hash
+      expect(data).to be_kind_of(Hash)
+      expect(data[:data][:attributes][:title]).to eq("hello")
+      expect(data[:data][:attributes][:body_markdown]).to be_falsey
+    end
+  end
+end