Merge branch 'fix-n-plus-one-when-getting-notification-settings-for-recipients' into 'master'

Use Goldiloader for handling N+1 queries

See merge request gitlab-org/gitlab-ce!18217

22 files changed, 188 insertions, 50 deletions

diff --git a/Gemfile b/Gemfile
index 7f5b1f1d3ef..647138cd90f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -441,3 +441,5 @@ gem 'grape_logging', '~> 1.7'
 
 # Asset synchronization
 gem 'asset_sync', '~> 2.2.0'
+
+gem 'goldiloader', '~> 2.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index a1150dfccdd..76e1a17155f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -320,6 +320,9 @@ GEM
       rubyntlm (~> 0.5)
     globalid (0.4.1)
       activesupport (>= 4.2.0)
+    goldiloader (2.0.1)
+      activerecord (>= 4.2, < 5.2)
+      activesupport (>= 4.2, < 5.2)
     gollum-grit_adapter (1.0.1)
       gitlab-grit (~> 2.7, >= 2.7.1)
     gollum-lib (4.2.7)
@@ -1067,6 +1070,7 @@ DEPENDENCIES
   gitlab-markup (~> 1.6.2)
   gitlab-styles (~> 2.3)
   gitlab_omniauth-ldap (~> 2.0.4)
+  goldiloader (~> 2.0)
   gollum-lib (~> 4.2)
   gollum-rugged_adapter (~> 0.4.4)
   gon (~> 6.1.0)
diff --git a/app/models/ci/runner.rb b/app/models/ci/runner.rb
index 5a4c56ec0dc..ee0d8df8eb7 100644
--- a/app/models/ci/runner.rb
+++ b/app/models/ci/runner.rb
@@ -13,7 +13,7 @@ module Ci
 
     has_many :builds
     has_many :runner_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-    has_many :projects, through: :runner_projects
+    has_many :projects, -> { auto_include(false) }, through: :runner_projects
 
     has_one :last_build, ->() { order('id DESC') }, class_name: 'Ci::Build'
 
diff --git a/app/models/clusters/cluster.rb b/app/models/clusters/cluster.rb
index 77947d515c1..e4a06f3f976 100644
--- a/app/models/clusters/cluster.rb
+++ b/app/models/clusters/cluster.rb
@@ -15,7 +15,7 @@ module Clusters
     belongs_to :user
 
     has_many :cluster_projects, class_name: 'Clusters::Project'
-    has_many :projects, through: :cluster_projects, class_name: '::Project'
+    has_many :projects, -> { auto_include(false) }, through: :cluster_projects, class_name: '::Project'
 
     # we force autosave to happen when we save `Cluster` model
     has_one :provider_gcp, class_name: 'Clusters::Providers::Gcp', autosave: true
diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index b45395343cc..d9416352f9c 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -48,7 +48,7 @@ module Issuable
     end
 
     has_many :label_links, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-    has_many :labels, through: :label_links
+    has_many :labels, -> { auto_include(false) }, through: :label_links
     has_many :todos, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
 
     has_one :metrics
diff --git a/app/models/concerns/resolvable_discussion.rb b/app/models/concerns/resolvable_discussion.rb
index 7c236369793..399abb67c9d 100644
--- a/app/models/concerns/resolvable_discussion.rb
+++ b/app/models/concerns/resolvable_discussion.rb
@@ -102,7 +102,7 @@ module ResolvableDiscussion
     yield(notes_relation)
 
     # Set the notes array to the updated notes
-    @notes = notes_relation.fresh.to_a # rubocop:disable Gitlab/ModuleWithInstanceVariables
+    @notes = notes_relation.fresh.auto_include(false).to_a # rubocop:disable Gitlab/ModuleWithInstanceVariables
 
     self.class.memoized_values.each do |name|
       clear_memoization(name)
diff --git a/app/models/deploy_key.rb b/app/models/deploy_key.rb
index 89a74b7dcb1..858b7ef533e 100644
--- a/app/models/deploy_key.rb
+++ b/app/models/deploy_key.rb
@@ -2,7 +2,7 @@ class DeployKey < Key
   include IgnorableColumn
 
   has_many :deploy_keys_projects, inverse_of: :deploy_key, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-  has_many :projects, through: :deploy_keys_projects
+  has_many :projects, -> { auto_include(false) }, through: :deploy_keys_projects
 
   scope :in_projects, ->(projects) { joins(:deploy_keys_projects).where('deploy_keys_projects.project_id in (?)', projects) }
   scope :are_public,  -> { where(public: true) }
diff --git a/app/models/deploy_token.rb b/app/models/deploy_token.rb
index fe726b156d4..b47b2ff4c3f 100644
--- a/app/models/deploy_token.rb
+++ b/app/models/deploy_token.rb
@@ -8,7 +8,7 @@ class DeployToken < ActiveRecord::Base
   default_value_for(:expires_at) { Forever.date }
 
   has_many :project_deploy_tokens, inverse_of: :deploy_token
-  has_many :projects, through: :project_deploy_tokens
+  has_many :projects, -> { auto_include(false) }, through: :project_deploy_tokens
 
   validate :ensure_at_least_one_scope
   before_save :ensure_token
diff --git a/app/models/fork_network.rb b/app/models/fork_network.rb
index 7f1728e8c77..aad3509b895 100644
--- a/app/models/fork_network.rb
+++ b/app/models/fork_network.rb
@@ -1,7 +1,7 @@
 class ForkNetwork < ActiveRecord::Base
   belongs_to :root_project, class_name: 'Project'
   has_many :fork_network_members
-  has_many :projects, through: :fork_network_members
+  has_many :projects, -> { auto_include(false) }, through: :fork_network_members
 
   after_create :add_root_as_member, if: :root_project
 
diff --git a/app/models/group.rb b/app/models/group.rb
index 8ff781059cc..202988d743d 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -12,9 +12,9 @@ class Group < Namespace
 
   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 :users, -> { auto_include(false) }, through: :group_members
   has_many :owners,
-    -> { where(members: { access_level: Gitlab::Access::OWNER }) },
+    -> { where(members: { access_level: Gitlab::Access::OWNER }).auto_include(false) },
     through: :group_members,
     source: :user
 
@@ -23,7 +23,7 @@ class Group < Namespace
 
   has_many :milestones
   has_many :project_group_links, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-  has_many :shared_projects, through: :project_group_links, source: :project
+  has_many :shared_projects, -> { auto_include(false) }, through: :project_group_links, source: :project
   has_many :notification_settings, dependent: :destroy, as: :source # rubocop:disable Cop/ActiveRecordDependent
   has_many :labels, class_name: 'GroupLabel'
   has_many :variables, class_name: 'Ci::GroupVariable'
diff --git a/app/models/issue.rb b/app/models/issue.rb
index 13d9e42bcc8..c1ffe6512ea 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -34,7 +34,7 @@ class Issue < ActiveRecord::Base
     dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
 
   has_many :issue_assignees
-  has_many :assignees, class_name: "User", through: :issue_assignees
+  has_many :assignees, -> { auto_include(false) }, class_name: "User", through: :issue_assignees
 
   validates :project, presence: true
 
diff --git a/app/models/label.rb b/app/models/label.rb
index de7f1d56c64..f3496884cff 100644
--- a/app/models/label.rb
+++ b/app/models/label.rb
@@ -18,8 +18,8 @@ class Label < ActiveRecord::Base
   has_many :lists, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :priorities, class_name: 'LabelPriority'
   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'
+  has_many :issues, -> { auto_include(false) }, through: :label_links, source: :target, source_type: 'Issue'
+  has_many :merge_requests, -> { auto_include(false) }, through: :label_links, source: :target, source_type: 'MergeRequest'
 
   before_validation :strip_whitespace_from_title_and_color
 
diff --git a/app/models/lfs_object.rb b/app/models/lfs_object.rb
index b7de46fa202..ed95613ee59 100644
--- a/app/models/lfs_object.rb
+++ b/app/models/lfs_object.rb
@@ -3,7 +3,7 @@ class LfsObject < ActiveRecord::Base
   include ObjectStorage::BackgroundMove
 
   has_many :lfs_objects_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-  has_many :projects, through: :lfs_objects_projects
+  has_many :projects, -> { auto_include(false) }, through: :lfs_objects_projects
 
   scope :with_files_stored_locally, -> { where(file_store: [nil, LfsObjectUploader::Store::LOCAL]) }
 
diff --git a/app/models/milestone.rb b/app/models/milestone.rb
index a66a0015827..8e33bab81c1 100644
--- a/app/models/milestone.rb
+++ b/app/models/milestone.rb
@@ -22,7 +22,7 @@ class Milestone < ActiveRecord::Base
   belongs_to :group
 
   has_many :issues
-  has_many :labels, -> { distinct.reorder('labels.title') },  through: :issues
+  has_many :labels, -> { distinct.reorder('labels.title').auto_include(false) }, through: :issues
   has_many :merge_requests
   has_many :events, as: :target, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
 
diff --git a/app/models/project.rb b/app/models/project.rb
index 3f805dd1fc9..ffd78d3ab70 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -138,11 +138,11 @@ class Project < ActiveRecord::Base
   has_one :packagist_service
 
   # TODO: replace these relations with the fork network versions
-  has_one  :forked_project_link,  foreign_key: "forked_to_project_id"
-  has_one  :forked_from_project,  through:   :forked_project_link
+  has_one  :forked_project_link, foreign_key: "forked_to_project_id"
+  has_one  :forked_from_project, -> { auto_include(false) }, through:   :forked_project_link
 
   has_many :forked_project_links, foreign_key: "forked_from_project_id"
-  has_many :forks,                through:     :forked_project_links, source: :forked_to_project
+  has_many :forks, -> { auto_include(false) }, through: :forked_project_links, source: :forked_to_project
   # TODO: replace these relations with the fork network versions
 
   has_one :root_of_fork_network,
@@ -150,7 +150,7 @@ class Project < ActiveRecord::Base
           inverse_of: :root_project,
           class_name: 'ForkNetwork'
   has_one :fork_network_member
-  has_one :fork_network, through: :fork_network_member
+  has_one :fork_network, -> { auto_include(false) }, through: :fork_network_member
 
   # Merge Requests for target project should be removed with it
   has_many :merge_requests, foreign_key: 'target_project_id'
@@ -167,27 +167,27 @@ class Project < ActiveRecord::Base
   has_many :protected_tags
 
   has_many :project_authorizations
-  has_many :authorized_users, through: :project_authorizations, source: :user, class_name: 'User'
+  has_many :authorized_users, -> { auto_include(false) }, through: :project_authorizations, source: :user, class_name: 'User'
   has_many :project_members, -> { where(requested_at: nil) },
     as: :source, dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
 
   alias_method :members, :project_members
-  has_many :users, through: :project_members
+  has_many :users, -> { auto_include(false) }, through: :project_members
 
   has_many :requesters, -> { where.not(requested_at: nil) },
     as: :source, class_name: 'ProjectMember', dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
   has_many :members_and_requesters, as: :source, class_name: 'ProjectMember'
 
   has_many :deploy_keys_projects
-  has_many :deploy_keys, through: :deploy_keys_projects
+  has_many :deploy_keys, -> { auto_include(false) }, through: :deploy_keys_projects
   has_many :users_star_projects
-  has_many :starrers, through: :users_star_projects, source: :user
+  has_many :starrers, -> { auto_include(false) }, through: :users_star_projects, source: :user
   has_many :releases
   has_many :lfs_objects_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-  has_many :lfs_objects, through: :lfs_objects_projects
+  has_many :lfs_objects, -> { auto_include(false) }, through: :lfs_objects_projects
   has_many :lfs_file_locks
   has_many :project_group_links
-  has_many :invited_groups, through: :project_group_links, source: :group
+  has_many :invited_groups, -> { auto_include(false) }, through: :project_group_links, source: :group
   has_many :pages_domains
   has_many :todos
   has_many :notification_settings, as: :source, dependent: :delete_all # rubocop:disable Cop/ActiveRecordDependent
@@ -199,7 +199,7 @@ class Project < ActiveRecord::Base
   has_one :statistics, class_name: 'ProjectStatistics'
 
   has_one :cluster_project, class_name: 'Clusters::Project'
-  has_many :clusters, through: :cluster_project, class_name: 'Clusters::Cluster'
+  has_many :clusters, -> { auto_include(false) }, through: :cluster_project, class_name: 'Clusters::Cluster'
 
   # Container repositories need to remove data from the container registry,
   # which is not managed by the DB. Hence we're still using dependent: :destroy
@@ -216,16 +216,16 @@ class Project < ActiveRecord::Base
   has_many :builds, class_name: 'Ci::Build', inverse_of: :project, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :build_trace_section_names, class_name: 'Ci::BuildTraceSectionName'
   has_many :runner_projects, class_name: 'Ci::RunnerProject'
-  has_many :runners, through: :runner_projects, source: :runner, class_name: 'Ci::Runner'
+  has_many :runners, -> { auto_include(false) }, through: :runner_projects, source: :runner, class_name: 'Ci::Runner'
   has_many :variables, class_name: 'Ci::Variable'
   has_many :triggers, class_name: 'Ci::Trigger'
   has_many :environments
   has_many :deployments
   has_many :pipeline_schedules, class_name: 'Ci::PipelineSchedule'
   has_many :project_deploy_tokens
-  has_many :deploy_tokens, through: :project_deploy_tokens
+  has_many :deploy_tokens, -> { auto_include(false) }, through: :project_deploy_tokens
 
-  has_many :active_runners, -> { active }, through: :runner_projects, source: :runner, class_name: 'Ci::Runner'
+  has_many :active_runners, -> { active.auto_include(false) }, through: :runner_projects, source: :runner, class_name: 'Ci::Runner'
 
   has_one :auto_devops, class_name: 'ProjectAutoDevops'
   has_many :custom_attributes, class_name: 'ProjectCustomAttribute'
diff --git a/app/models/todo.rb b/app/models/todo.rb
index a2ab405fdbe..aad2c1dac4e 100644
--- a/app/models/todo.rb
+++ b/app/models/todo.rb
@@ -22,7 +22,7 @@ class Todo < ActiveRecord::Base
   belongs_to :author, class_name: "User"
   belongs_to :note
   belongs_to :project
-  belongs_to :target, polymorphic: true, touch: true # rubocop:disable Cop/PolymorphicAssociations
+  belongs_to :target, -> { auto_include(false) }, polymorphic: true, touch: true # rubocop:disable Cop/PolymorphicAssociations
   belongs_to :user
 
   delegate :name, :email, to: :author, prefix: true, allow_nil: true
diff --git a/app/models/user.rb b/app/models/user.rb
index 42bb27d4753..d5c5c0964c5 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -96,23 +96,23 @@ class User < ActiveRecord::Base
   # Groups
   has_many :members
   has_many :group_members, -> { where(requested_at: nil) }, source: 'GroupMember'
-  has_many :groups, through: :group_members
-  has_many :owned_groups, -> { where members: { access_level: Gitlab::Access::OWNER } }, through: :group_members, source: :group
-  has_many :masters_groups, -> { where members: { access_level: Gitlab::Access::MASTER } }, through: :group_members, source: :group
+  has_many :groups, -> { auto_include(false) }, through: :group_members
+  has_many :owned_groups, -> { where(members: { access_level: Gitlab::Access::OWNER }).auto_include(false) }, through: :group_members, source: :group
+  has_many :masters_groups, -> { where(members: { access_level: Gitlab::Access::MASTER }).auto_include(false) }, through: :group_members, source: :group
 
   # Projects
-  has_many :groups_projects,          through: :groups, source: :projects
-  has_many :personal_projects,        through: :namespace, source: :projects
+  has_many :groups_projects, -> { auto_include(false) }, through: :groups, source: :projects
+  has_many :personal_projects, -> { auto_include(false) }, through: :namespace, source: :projects
   has_many :project_members, -> { where(requested_at: nil) }
-  has_many :projects,                 through: :project_members
-  has_many :created_projects,         foreign_key: :creator_id, class_name: 'Project'
+  has_many :projects, -> { auto_include(false) }, through: :project_members
+  has_many :created_projects, foreign_key: :creator_id, class_name: 'Project'
   has_many :users_star_projects, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
-  has_many :starred_projects, through: :users_star_projects, source: :project
+  has_many :starred_projects, -> { auto_include(false) }, through: :users_star_projects, source: :project
   has_many :project_authorizations
-  has_many :authorized_projects, through: :project_authorizations, source: :project
+  has_many :authorized_projects, -> { auto_include(false) }, through: :project_authorizations, source: :project
 
   has_many :user_interacted_projects
-  has_many :project_interactions, through: :user_interacted_projects, source: :project, class_name: 'Project'
+  has_many :project_interactions, -> { auto_include(false) }, through: :user_interacted_projects, source: :project, class_name: 'Project'
 
   has_many :snippets,                 dependent: :destroy, foreign_key: :author_id # rubocop:disable Cop/ActiveRecordDependent
   has_many :notes,                    dependent: :destroy, foreign_key: :author_id # rubocop:disable Cop/ActiveRecordDependent
@@ -132,7 +132,7 @@ class User < ActiveRecord::Base
   has_many :triggers,                 dependent: :destroy, class_name: 'Ci::Trigger', foreign_key: :owner_id # rubocop:disable Cop/ActiveRecordDependent
 
   has_many :issue_assignees
-  has_many :assigned_issues, class_name: "Issue", through: :issue_assignees, source: :issue
+  has_many :assigned_issues, -> { auto_include(false) }, class_name: "Issue", through: :issue_assignees, source: :issue
   has_many :assigned_merge_requests,  dependent: :nullify, foreign_key: :assignee_id, class_name: "MergeRequest" # rubocop:disable Cop/ActiveRecordDependent
 
   has_many :custom_attributes, class_name: 'UserCustomAttribute'
diff --git a/changelogs/unreleased/fix-n-plus-one-when-getting-notification-settings-for-recipients.yml b/changelogs/unreleased/fix-n-plus-one-when-getting-notification-settings-for-recipients.yml
new file mode 100644
index 00000000000..837bfed19b7
--- /dev/null
+++ b/changelogs/unreleased/fix-n-plus-one-when-getting-notification-settings-for-recipients.yml
@@ -0,0 +1,5 @@
+---
+title: Add Goldiloader to fix N+1 issues when calculating email recipients
+merge_request:
+author:
+type: performance
diff --git a/rubocop/cop/gitlab/has_many_through_scope.rb b/rubocop/cop/gitlab/has_many_through_scope.rb
new file mode 100644
index 00000000000..770a2a0529f
--- /dev/null
+++ b/rubocop/cop/gitlab/has_many_through_scope.rb
@@ -0,0 +1,45 @@
+require 'gitlab/styles/rubocop/model_helpers'
+
+module RuboCop
+  module Cop
+    module Gitlab
+      class HasManyThroughScope < RuboCop::Cop::Cop
+        include ::Gitlab::Styles::Rubocop::ModelHelpers
+
+        MSG = 'Always provide an explicit scope calling auto_include(false) when using has_many :through'.freeze
+
+        def_node_search :through?, <<~PATTERN
+          (pair (sym :through) _)
+        PATTERN
+
+        def_node_matcher :has_many_through?, <<~PATTERN
+          (send nil? :has_many ... #through?)
+        PATTERN
+
+        def_node_search :disables_auto_include?, <<~PATTERN
+          (send _ :auto_include false)
+        PATTERN
+
+        def_node_matcher :scope_disables_auto_include?, <<~PATTERN
+          (block (send nil? :lambda) _ #disables_auto_include?)
+        PATTERN
+
+        def on_send(node)
+          return unless in_model?(node)
+          return unless has_many_through?(node)
+
+          target = node
+          scope_argument = node.children[3]
+
+          if scope_argument.children[0].children.last == :lambda
+            return if scope_disables_auto_include?(scope_argument)
+
+            target = scope_argument
+          end
+
+          add_offense(target, location: :expression)
+        end
+      end
+    end
+  end
+end
diff --git a/rubocop/rubocop.rb b/rubocop/rubocop.rb
index 406ec95ffc9..c2254332e7d 100644
--- a/rubocop/rubocop.rb
+++ b/rubocop/rubocop.rb
@@ -1,7 +1,8 @@
 # rubocop:disable Naming/FileName
+require_relative 'cop/gitlab/has_many_through_scope'
+require_relative 'cop/gitlab/httparty'
 require_relative 'cop/gitlab/module_with_instance_variables'
 require_relative 'cop/gitlab/predicate_memoization'
-require_relative 'cop/gitlab/httparty'
 require_relative 'cop/include_sidekiq_worker'
 require_relative 'cop/line_break_around_conditional_block'
 require_relative 'cop/migration/add_column'
diff --git a/spec/requests/api/pipeline_schedules_spec.rb b/spec/requests/api/pipeline_schedules_spec.rb
index 7ea25059756..91d4d5d3de9 100644
--- a/spec/requests/api/pipeline_schedules_spec.rb
+++ b/spec/requests/api/pipeline_schedules_spec.rb
@@ -17,6 +17,17 @@ describe API::PipelineSchedules do
         pipeline_schedule.pipelines << build(:ci_pipeline, project: project)
       end
 
+      def create_pipeline_schedules(count)
+        create_list(:ci_pipeline_schedule, count, project: project)
+          .each do |pipeline_schedule|
+          create(:user).tap do |user|
+            project.add_developer(user)
+            pipeline_schedule.update_attributes(owner: user)
+          end
+          pipeline_schedule.pipelines << build(:ci_pipeline, project: project)
+        end
+      end
+
       it 'returns list of pipeline_schedules' do
         get api("/projects/#{project.id}/pipeline_schedules", developer)
 
@@ -26,18 +37,14 @@ describe API::PipelineSchedules do
       end
 
       it 'avoids N + 1 queries' do
+        # We need at least two users to trigger a preload for that relation.
+        create_pipeline_schedules(1)
+
         control_count = ActiveRecord::QueryRecorder.new do
           get api("/projects/#{project.id}/pipeline_schedules", developer)
         end.count
 
-        create_list(:ci_pipeline_schedule, 10, project: project)
-          .each do |pipeline_schedule|
-          create(:user).tap do |user|
-            project.add_developer(user)
-            pipeline_schedule.update_attributes(owner: user)
-          end
-          pipeline_schedule.pipelines << build(:ci_pipeline, project: project)
-        end
+        create_pipeline_schedules(10)
 
         expect do
           get api("/projects/#{project.id}/pipeline_schedules", developer)
diff --git a/spec/rubocop/cop/gitlab/has_many_through_scope_spec.rb b/spec/rubocop/cop/gitlab/has_many_through_scope_spec.rb
new file mode 100644
index 00000000000..6d769c8e6fd
--- /dev/null
+++ b/spec/rubocop/cop/gitlab/has_many_through_scope_spec.rb
@@ -0,0 +1,74 @@
+require 'spec_helper'
+
+require 'rubocop'
+require 'rubocop/rspec/support'
+
+require_relative '../../../../rubocop/cop/gitlab/has_many_through_scope'
+
+describe RuboCop::Cop::Gitlab::HasManyThroughScope do # rubocop:disable RSpec/FilePath
+  include CopHelper
+
+  subject(:cop) { described_class.new }
+
+  context 'in a model file' do
+    before do
+      allow(cop).to receive(:in_model?).and_return(true)
+    end
+
+    context 'when the model does not use has_many :through' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<-RUBY)
+          class User < ActiveRecord::Base
+            has_many :tags, source: 'UserTag'
+          end
+        RUBY
+      end
+    end
+
+    context 'when the model uses has_many :through' do
+      context 'when the association has no scope defined' do
+        it 'registers an offense on the association' do
+          expect_offense(<<-RUBY)
+            class User < ActiveRecord::Base
+              has_many :tags, through: :user_tags
+              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ #{described_class::MSG}
+            end
+           RUBY
+        end
+      end
+
+      context 'when the association has a scope defined' do
+        context 'when the scope does not disable auto-loading' do
+          it 'registers an offense on the scope' do
+            expect_offense(<<-RUBY)
+              class User < ActiveRecord::Base
+                has_many :tags, -> { where(active: true) }, through: :user_tags
+                                ^^^^^^^^^^^^^^^^^^^^^^^^^^ #{described_class::MSG}
+              end
+             RUBY
+          end
+        end
+
+        context 'when the scope has auto_include(false)' do
+          it 'does not register an offense' do
+            expect_no_offenses(<<-RUBY)
+              class User < ActiveRecord::Base
+                has_many :tags, -> { where(active: true).auto_include(false).reorder(nil) }, through: :user_tags
+              end
+            RUBY
+          end
+        end
+      end
+    end
+  end
+
+  context 'outside of a migration spec file' do
+    it 'does not register an offense' do
+      expect_no_offenses(<<-RUBY)
+        class User < ActiveRecord::Base
+          has_many :tags, through: :user_tags
+        end
+      RUBY
+    end
+  end
+end