api support for merge_requests_events system hook

doc/api/system_hooks.md

@@ -33,6 +33,7 @@ Example response:
     "created_at":"2016-10-31T12:32:15.192Z",
     "push_events":true,
     "tag_push_events":false,
+    "merge_requests_events": true,
     "enable_ssl_verification":true
   }
 ]

lib/api/entities.rb

@@ -65,12 +65,12 @@ module API
     end
     class Hook < Grape::Entity
-      expose :id, :url, :created_at, :push_events, :tag_push_events, :repository_update_events
+      expose :id, :url, :created_at, :push_events, :tag_push_events, :merge_requests_events, :repository_update_events
       expose :enable_ssl_verification
     end
     class ProjectHook < Hook
-      expose :project_id, :issues_events, :merge_requests_events
+      expose :project_id, :issues_events
       expose :note_events, :pipeline_events, :wiki_page_events
       expose :job_events
     end

lib/api/system_hooks.rb

@@ -26,6 +26,7 @@ module API
         optional :token, type: String, desc: 'The token used to validate payloads'
         optional :push_events, type: Boolean, desc: "Trigger hook on push events"
         optional :tag_push_events, type: Boolean, desc: "Trigger hook on tag push events"
+        optional :merge_requests_events, type: Boolean, desc: "Trigger hook on tag push events"
         optional :enable_ssl_verification, type: Boolean, desc: "Do SSL verification when triggering the hook"
       end
       post do

spec/requests/api/system_hooks_spec.rb

@@ -36,6 +36,7 @@ describe API::SystemHooks do
         expect(json_response.first['url']).to eq(hook.url)
         expect(json_response.first['push_events']).to be false
         expect(json_response.first['tag_push_events']).to be false
+        expect(json_response.first['merge_requests_events']).to be false
         expect(json_response.first['repository_update_events']).to be true
       end
     end
@@ -67,11 +68,28 @@ describe API::SystemHooks do
     end
     it 'sets default values for events' do
-      post api('/hooks', admin), url: 'http://mep.mep', enable_ssl_verification: true
+      post api('/hooks', admin), url: 'http://mep.mep'
       expect(response).to have_gitlab_http_status(201)
       expect(json_response['enable_ssl_verification']).to be true
+      expect(json_response['push_events']).to be false
       expect(json_response['tag_push_events']).to be false
+      expect(json_response['merge_requests_events']).to be false
+    end
+
+    it 'sets explicit values for events' do
+      post api('/hooks', admin),
+        url: 'http://mep.mep',
+        enable_ssl_verification: false,
+        push_events: true,
+        tag_push_events: true,
+        merge_requests_events: true
+
+      expect(response).to have_http_status(201)
+      expect(json_response['enable_ssl_verification']).to be false
+      expect(json_response['push_events']).to be true
+      expect(json_response['tag_push_events']).to be true
+      expect(json_response['merge_requests_events']).to be true
     end
   end