execute system hooks from project

app/models/hooks/system_hook.rb

@@ -2,7 +2,8 @@ class SystemHook < WebHook
   TRIGGERS = {
     repository_update_hooks: :repository_update_events,
     push_hooks:              :push_events,
-    tag_push_hooks:          :tag_push_events
+    tag_push_hooks:          :tag_push_events,
+    merge_request_hooks:     :merge_requests_events
   }.freeze
   TRIGGERS.each do |trigger, event|
@@ -11,4 +12,5 @@ class SystemHook < WebHook
   default_value_for :push_events, false
   default_value_for :repository_update_events, true
+  default_value_for :merge_requests_events, false
 end

app/models/project.rb

@@ -974,6 +974,10 @@ class Project < ActiveRecord::Base
         hook.async_execute(data, hooks_scope.to_s)
       end
     end
+
+    SystemHook.public_send(hooks_scope).each do |hook| # rubocop:disable GitlabSecurity/PublicSend
+      hook.async_execute(data, hooks_scope.to_s)
+    end
   end
   def execute_services(data, hooks_scope = :push_hooks)

spec/models/hooks/system_hook_spec.rb

@@ -7,7 +7,8 @@ describe SystemHook do
     it 'sets defined default parameters' do
       attrs = {
         push_events: false,
-        repository_update_events: true
+        repository_update_events: true,
+        merge_requests_events: false
       }
       expect(system_hook).to have_attributes(attrs)
     end

spec/models/project_spec.rb

@@ -3177,4 +3177,27 @@ describe Project do
       expect { project.write_repository_config }.not_to raise_error
     end
   end
+
+  describe '#execute_hooks' do
+    it 'executes the projects hooks with the specified scope' do
+      hook1 = create(:project_hook, merge_requests_events: true, tag_push_events: false)
+      hook2 = create(:project_hook, merge_requests_events: false, tag_push_events: true)
+      project = create(:project, hooks: [hook1, hook2])
+
+      expect_any_instance_of(ProjectHook).to receive(:async_execute).once
+
+      project.execute_hooks({}, :tag_push_hooks)
+    end
+
+    it 'executes the system hooks with the specified scope' do
+      create :system_hook, merge_requests_events: true, tag_push_events: false
+      create :system_hook, merge_requests_events: false, tag_push_events: true
+      allow_any_instance_of(SystemHook).to receive(:async_execute).once
+      project = create :project
+
+      expect_any_instance_of(SystemHook).to receive(:async_execute).once
+
+      project.execute_hooks({}, :tag_push_hooks)
+    end
+  end
 end