Fix Project#group_runners_enabled as it was doing nothing

app/models/project.rb

@@ -234,7 +234,7 @@ class Project < ActiveRecord::Base
   has_many :custom_attributes, class_name: 'ProjectCustomAttribute'
   has_many :project_badges, class_name: 'ProjectBadge'
-  has_one :ci_cd_settings, class_name: 'ProjectCiCdSetting'
+  has_one :ci_cd_settings, class_name: 'ProjectCiCdSetting', inverse_of: :project, autosave: true
   accepts_nested_attributes_for :variables, allow_destroy: true
   accepts_nested_attributes_for :project_feature, update_only: true
@@ -331,6 +331,11 @@ class Project < ActiveRecord::Base
   scope :with_issues_available_for_user, ->(current_user) { with_feature_available_for_user(:issues, current_user) }
   scope :with_merge_requests_enabled, -> { with_feature_enabled(:merge_requests) }
+  scope :with_group_runners_enabled, -> do
+    joins(:ci_cd_settings)
+    .where(project_ci_cd_settings: { group_runners_enabled: true })
+  end
+
   enum auto_cancel_pending_pipelines: { disabled: 0, enabled: 1 }
   chronic_duration_attr :build_timeout_human_readable, :build_timeout, default: 3600

app/models/project_ci_cd_setting.rb

 class ProjectCiCdSetting < ActiveRecord::Base
-  belongs_to :project
+  belongs_to :project, inverse_of: :ci_cd_settings
   # The version of the schema that first introduced this model/table.
   MINIMUM_SCHEMA_VERSION = 20180403035759

app/services/ci/register_job_service.rb

@@ -91,7 +91,10 @@ module Ci
     def builds_for_group_runner
       hierarchy_groups = Gitlab::GroupHierarchy.new(runner.groups).base_and_descendants
       projects = Project.where(namespace_id: hierarchy_groups)
-      new_builds.where(project: projects.without_deleted.with_builds_enabled).order('created_at ASC')
+        .with_group_runners_enabled
+        .with_builds_enabled
+        .without_deleted
+      new_builds.where(project: projects).order('created_at ASC')
     end
     def running_builds_for_shared_runners

spec/services/ci/register_job_service_spec.rb

@@ -2,13 +2,13 @@ require 'spec_helper'
 module Ci
   describe RegisterJobService do
-    let!(:project) { create :project, shared_runners_enabled: false }
-    let!(:group) { create :group }
-    let!(:pipeline) { create :ci_pipeline, project: project }
-    let!(:pending_job) { create :ci_build, pipeline: pipeline }
-    let!(:shared_runner) { create :ci_runner, is_shared: true }
-    let!(:specific_runner) { create :ci_runner, is_shared: false }
-    let!(:group_runner) { create :ci_runner, groups: [group], runner_type: :group_type }
+    set(:group) { create(:group) }
+    set(:project) { create(:project, group: group, shared_runners_enabled: false, group_runners_enabled: false) }
+    set(:pipeline) { create(:ci_pipeline, project: project) }
+    let!(:shared_runner) { create(:ci_runner, is_shared: true) }
+    let!(:specific_runner) { create(:ci_runner, is_shared: false) }
+    let!(:group_runner) { create(:ci_runner, groups: [group], runner_type: :group_type) }
+    let!(:pending_job) { create(:ci_build, pipeline: pipeline) }
     before do
       specific_runner.assign_to(project)
@@ -152,7 +152,7 @@ module Ci
       context 'disallow when builds are disabled' do
         before do
-          project.update(shared_runners_enabled: true)
+          project.update(shared_runners_enabled: true, group_runners_enabled: true)
           project.project_feature.update_attribute(:builds_access_level, ProjectFeature::DISABLED)
         end
@@ -162,7 +162,13 @@ module Ci
           it { expect(build).to be_nil }
         end
-        context 'and uses specific runner' do
+        context 'and uses group runner' do
+          let(:build) { execute(group_runner) }
+
+          it { expect(build).to be_nil }
+        end
+
+        context 'and uses project runner' do
           let(:build) { execute(specific_runner) }
           it { expect(build).to be_nil }
@@ -171,7 +177,7 @@ module Ci
       context 'allow group runners' do
         before do
-          project.update!(group_runners_enabled: true, group: group)
+          project.update!(group_runners_enabled: true)
         end
         context 'for multiple builds' do
@@ -230,7 +236,7 @@ module Ci
       context 'disallow group runners' do
         before do
-          project.update(group_runners_enabled: false)
+          project.update!(group_runners_enabled: false)
         end
         context 'group runner' do