Added Cop to blacklist the use of `dependent:`

This is allowed for existing instances so we don't end up 76 offenses
right away, but for new code one should _only_ use this if they _have_
to remove non database data. Even then it's usually better to do this in
a service class as this gives you more control over how to remove the
data (e.g. in bulk).

app/models/appearance.rb

@@ -10,5 +10,5 @@ class Appearance < ActiveRecord::Base
   mount_uploader :logo,         AttachmentUploader
   mount_uploader :header_logo,  AttachmentUploader
-  has_many :uploads, as: :model, dependent: :destroy
+  has_many :uploads, as: :model, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
 end

app/models/board.rb

 class Board < ActiveRecord::Base
   belongs_to :project
-  has_many :lists, -> { order(:list_type, :position) }, dependent: :delete_all
+  has_many :lists, -> { order(:list_type, :position) }, dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
   validates :project, presence: true

app/models/ci/pipeline.rb

@@ -14,7 +14,7 @@ module Ci
     has_many :stages
     has_many :statuses, class_name: 'CommitStatus', foreign_key: :commit_id
     has_many :builds, foreign_key: :commit_id
-    has_many :trigger_requests, dependent: :destroy, foreign_key: :commit_id
+    has_many :trigger_requests, dependent: :destroy, foreign_key: :commit_id # rubocop:disable Cop/ActiveRecordDependent
     # Merge requests for which the current pipeline is running against
     # the merge request's latest commit.

app/models/ci/runner.rb

@@ -8,7 +8,7 @@ module Ci
     FORM_EDITABLE = %i[description tag_list active run_untagged locked].freeze
     has_many :builds
-    has_many :runner_projects, dependent: :destroy
+    has_many :runner_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
     has_many :projects, through: :runner_projects
     has_one :last_build, ->() { order('id DESC') }, class_name: 'Ci::Build'

app/models/concerns/awardable.rb

@@ -2,7 +2,7 @@ module Awardable
   extend ActiveSupport::Concern
   included do
-    has_many :award_emoji, -> { includes(:user).order(:id) }, as: :awardable, dependent: :destroy
+    has_many :award_emoji, -> { includes(:user).order(:id) }, as: :awardable, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
     if self < Participable
       # By default we always load award_emoji user association

app/models/concerns/issuable.rb

@@ -30,7 +30,7 @@ module Issuable
     belongs_to :updated_by, class_name: "User"
     belongs_to :last_edited_by, class_name: 'User'
     belongs_to :milestone
-    has_many :notes, as: :noteable, inverse_of: :noteable, dependent: :destroy do
+    has_many :notes, as: :noteable, inverse_of: :noteable, dependent: :destroy do # rubocop:disable Cop/ActiveRecordDependent
       def authors_loaded?
         # We check first if we're loaded to not load unnecessarily.
         loaded? && to_a.all? { |note| note.association(:author).loaded? }
@@ -42,9 +42,9 @@ module Issuable
       end
     end
-    has_many :label_links, as: :target, dependent: :destroy
+    has_many :label_links, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
     has_many :labels, through: :label_links
-    has_many :todos, as: :target, dependent: :destroy
+    has_many :todos, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
     has_one :metrics

app/models/concerns/protected_ref.rb

@@ -17,7 +17,7 @@ module ProtectedRef
   class_methods do
     def protected_ref_access_levels(*types)
       types.each do |type|
-        has_many :"#{type}_access_levels", dependent: :destroy
+        has_many :"#{type}_access_levels", dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
         validates :"#{type}_access_levels", length: { is: 1, message: "are restricted to a single instance per #{self.model_name.human}." }

app/models/concerns/routable.rb

@@ -4,8 +4,8 @@ module Routable
   extend ActiveSupport::Concern
   included do
-    has_one :route, as: :source, autosave: true, dependent: :destroy
-    has_many :redirect_routes, as: :source, autosave: true, dependent: :destroy
+    has_one :route, as: :source, autosave: true, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
+    has_many :redirect_routes, as: :source, autosave: true, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
     validates_associated :route
     validates :route, presence: true

app/models/concerns/spammable.rb

@@ -8,7 +8,7 @@ module Spammable
   end
   included do
-    has_one :user_agent_detail, as: :subject, dependent: :destroy
+    has_one :user_agent_detail, as: :subject, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
     attr_accessor :spam
     attr_accessor :spam_log

app/models/concerns/subscribable.rb

@@ -9,7 +9,7 @@ module Subscribable
   extend ActiveSupport::Concern
   included do
-    has_many :subscriptions, dependent: :destroy, as: :subscribable
+    has_many :subscriptions, dependent: :destroy, as: :subscribable # rubocop:disable Cop/ActiveRecordDependent
   end
   def subscribed?(user, project = nil)

app/models/concerns/time_trackable.rb

@@ -18,7 +18,7 @@ module TimeTrackable
     validates :time_estimate, numericality: { message: 'has an invalid format' }, allow_nil: false
     validate  :check_negative_time_spent
-    has_many :timelogs, dependent: :destroy
+    has_many :timelogs, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   end
   def spend_time(options)

app/models/deploy_key.rb

 class DeployKey < Key
-  has_many :deploy_keys_projects, dependent: :destroy
+  has_many :deploy_keys_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :projects, through: :deploy_keys_projects
   scope :in_projects, ->(projects) { joins(:deploy_keys_projects).where('deploy_keys_projects.project_id in (?)', projects) }

app/models/environment.rb

@@ -6,7 +6,7 @@ class Environment < ActiveRecord::Base
   belongs_to :project, required: true, validate: true
-  has_many :deployments, dependent: :destroy
+  has_many :deployments, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_one :last_deployment, -> { order('deployments.id DESC') }, class_name: 'Deployment'
   before_validation :nullify_external_url

app/models/group.rb

@@ -8,7 +8,7 @@ class Group < Namespace
   include Referable
   include SelectForProjectAuthorization
-  has_many :group_members, -> { where(requested_at: nil) }, dependent: :destroy, as: :source
+  has_many :group_members, -> { where(requested_at: nil) }, dependent: :destroy, as: :source # rubocop:disable Cop/ActiveRecordDependent
   alias_method :members, :group_members
   has_many :users, through: :group_members
   has_many :owners,
@@ -16,11 +16,11 @@ class Group < Namespace
     through: :group_members,
     source: :user
-  has_many :requesters, -> { where.not(requested_at: nil) }, dependent: :destroy, as: :source, class_name: 'GroupMember'
-  has_many :project_group_links, dependent: :destroy
+  has_many :requesters, -> { where.not(requested_at: nil) }, dependent: :destroy, as: :source, class_name: 'GroupMember' # rubocop:disable Cop/ActiveRecordDependent
+  has_many :project_group_links, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :shared_projects, through: :project_group_links, source: :project
-  has_many :notification_settings, dependent: :destroy, as: :source
+  has_many :notification_settings, dependent: :destroy, as: :source # rubocop:disable Cop/ActiveRecordDependent
   has_many :labels, class_name: 'GroupLabel'
   validate :avatar_type, if: ->(user) { user.avatar.present? && user.avatar_changed? }
@@ -31,7 +31,7 @@ class Group < Namespace
   validates :two_factor_grace_period, presence: true, numericality: { greater_than_or_equal_to: 0 }
   mount_uploader :avatar, AvatarUploader
-  has_many :uploads, as: :model, dependent: :destroy
+  has_many :uploads, as: :model, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   after_create :post_create_hook
   after_destroy :post_destroy_hook

app/models/hooks/web_hook.rb

@@ -12,7 +12,7 @@ class WebHook < ActiveRecord::Base
   default_value_for :repository_update_events, false
   default_value_for :enable_ssl_verification, true
-  has_many :web_hook_logs, dependent: :destroy
+  has_many :web_hook_logs, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   scope :push_hooks, -> { where(push_events: true) }
   scope :tag_push_hooks, -> { where(tag_push_events: true) }

app/models/issue.rb

@@ -23,9 +23,14 @@ class Issue < ActiveRecord::Base
   belongs_to :project
   belongs_to :moved_to, class_name: 'Issue'
-  has_many :events, as: :target, dependent: :destroy
-  has_many :merge_requests_closing_issues, class_name: 'MergeRequestsClosingIssues'
+  has_many :events, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
+  has_many :merge_requests_closing_issues,
+    class_name: 'MergeRequestsClosingIssues',
+    dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
+
+  has_many :issue_assignees
+  has_many :assignees, class_name: "User", through: :issue_assignees
   has_many :issue_assignees
   has_many :assignees, class_name: "User", through: :issue_assignees

app/models/label.rb

@@ -15,9 +15,9 @@ class Label < ActiveRecord::Base
   default_value_for :color, DEFAULT_COLOR
-  has_many :lists, dependent: :destroy
+  has_many :lists, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :priorities, class_name: 'LabelPriority'
-  has_many :label_links, dependent: :destroy
+  has_many :label_links, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :issues, through: :label_links, source: :target, source_type: 'Issue'
   has_many :merge_requests, through: :label_links, source: :target, source_type: 'MergeRequest'

app/models/lfs_object.rb

 class LfsObject < ActiveRecord::Base
-  has_many :lfs_objects_projects, dependent: :destroy
+  has_many :lfs_objects_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :projects, through: :lfs_objects_projects
   validates :oid, presence: true, uniqueness: true

app/models/merge_request.rb

@@ -18,9 +18,11 @@ class MergeRequest < ActiveRecord::Base
   belongs_to :head_pipeline, foreign_key: "head_pipeline_id", class_name: "Ci::Pipeline"
-  has_many :events, as: :target, dependent: :destroy
-  has_many :merge_requests_closing_issues, class_name: 'MergeRequestsClosingIssues'
+  has_many :events, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
+  has_many :merge_requests_closing_issues,
+    class_name: 'MergeRequestsClosingIssues',
+    dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
   belongs_to :assignee, class_name: "User"

app/models/milestone.rb

@@ -21,7 +21,7 @@ class Milestone < ActiveRecord::Base
   has_many :issues
   has_many :labels, -> { distinct.reorder('labels.title') },  through: :issues
   has_many :merge_requests
-  has_many :events, as: :target, dependent: :destroy
+  has_many :events, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   scope :active, -> { with_state(:active) }
   scope :closed, -> { with_state(:closed) }