extract concern for hook triggers

app/models/concerns/triggerable_hooks.rb

+module TriggerableHooks
+  AVAILABLE_TRIGGERS = {
+    repository_update_hooks:  :repository_update_events,
+    push_hooks:               :push_events,
+    tag_push_hooks:           :tag_push_events,
+    issue_hooks:              :issues_events,
+    confidential_issue_hooks: :confidential_issues_events,
+    note_hooks:               :note_events,
+    merge_request_hooks:      :merge_requests_events,
+    job_hooks:                :job_events,
+    pipeline_hooks:           :pipeline_events,
+    wiki_page_hooks:          :wiki_page_events
+  }.freeze
+
+  extend ActiveSupport::Concern
+
+  class_methods do
+    attr_reader :triggerable_hooks
+
+    private
+
+    def triggerable_hooks(hooks)
+      triggers = AVAILABLE_TRIGGERS.slice(*hooks)
+      const_set('TRIGGERS', triggers)
+
+      self::TRIGGERS.each do |trigger, event|
+        scope trigger, -> { where(event => true) }
+      end
+    end
+  end
+end

app/models/hooks/project_hook.rb

 class ProjectHook < WebHook
-  TRIGGERS = {
-    push_hooks:               :push_events,
-    tag_push_hooks:           :tag_push_events,
-    issue_hooks:              :issues_events,
-    confidential_issue_hooks: :confidential_issues_events,
-    note_hooks:               :note_events,
-    merge_request_hooks:      :merge_requests_events,
-    job_hooks:                :job_events,
-    pipeline_hooks:           :pipeline_events,
-    wiki_page_hooks:          :wiki_page_events
-  }.freeze
+  include TriggerableHooks
 
-  TRIGGERS.each do |trigger, event|
-    scope trigger, -> { where(event => true) }
-  end
+  triggerable_hooks only: [
+    :push_hooks,
+    :tag_push_hooks,
+    :issue_hooks,
+    :confidential_issue_hooks,
+    :note_hooks,
+    :merge_request_hooks,
+    :job_hooks,
+    :pipeline_hooks,
+    :wiki_page_hooks
+  ]
 
   belongs_to :project
   validates :project, presence: true

app/models/hooks/system_hook.rb

 class SystemHook < WebHook
-  TRIGGERS = {
-    repository_update_hooks: :repository_update_events,
-    push_hooks:              :push_events,
-    tag_push_hooks:          :tag_push_events,
-    merge_request_hooks:     :merge_requests_events
-  }.freeze
+  include TriggerableHooks
 
-  TRIGGERS.each do |trigger, event|
-    scope trigger, -> { where(event => true) }
-  end
+  triggerable_hooks only: [
+    :repository_update_hooks,
+    :push_hooks,
+    :tag_push_hooks,
+    :merge_request_hooks
+  ]
 
   default_value_for :push_events, false
   default_value_for :repository_update_events, true

spec/models/concerns/triggerable_hooks_spec.rb

+require 'rails_helper'
+
+RSpec.describe TriggerableHooks do
+  before do
+    class TestableHook < WebHook
+      include TriggerableHooks
+      triggerable_hooks only: [:push_hooks]
+    end
+  end
+
+  describe 'scopes' do
+    it 'defines a scope for each of the requested triggers' do
+      expect(TestableHook).to respond_to :push_hooks
+      expect(TestableHook).not_to respond_to :tag_push_hooks
+    end
+  end
+end