Add group milestones API method to api.js

app/assets/javascripts/api.js

@@ -9,6 +9,7 @@ const Api = {
   groupsPath: '/api/:version/groups.json',
   groupPath: '/api/:version/groups/:id',
   groupMembersPath: '/api/:version/groups/:id/members',
+  groupMilestonesPath: '/api/:version/groups/:id/milestones',
   subgroupsPath: '/api/:version/groups/:id/subgroups',
   namespacesPath: '/api/:version/namespaces.json',
   groupPackagesPath: '/api/:version/groups/:id/packages',
@@ -110,6 +111,17 @@ const Api = {
     });
   },
 
+  groupMilestones(id, options) {
+    const url = Api.buildUrl(this.groupMilestonesPath).replace(':id', encodeURIComponent(id));
+
+    return axios.get(url, {
+      params: {
+        per_page: DEFAULT_PER_PAGE,
+        ...options,
+      },
+    });
+  },
+
   // Return groups list. Filtered by query
   groups(query, options, callback = () => {}) {
     const url = Api.buildUrl(Api.groupsPath);

spec/frontend/api_spec.js

@@ -149,6 +149,36 @@ describe('Api', () => {
     });
   });
 
+  describe('groupMilestones', () => {
+    it('fetches group milestones', done => {
+      const groupId = '16';
+      const expectedUrl = `${dummyUrlRoot}/api/${dummyApiVersion}/groups/${groupId}/milestones`;
+      const expectedData = [
+        {
+          id: 12,
+          iid: 3,
+          group_id: 16,
+          title: '10.0',
+          description: 'Version',
+          due_date: '2013-11-29',
+          start_date: '2013-11-10',
+          state: 'active',
+          updated_at: '2013-10-02T09:24:18Z',
+          created_at: '2013-10-02T09:24:18Z',
+          web_url: 'https://gitlab.com/groups/gitlab-org/-/milestones/42',
+        },
+      ];
+      mock.onGet(expectedUrl).reply(httpStatus.OK, expectedData);
+
+      Api.groupMilestones(groupId)
+        .then(({ data }) => {
+          expect(data).toEqual(expectedData);
+        })
+        .then(done)
+        .catch(done.fail);
+    });
+  });
+
   describe('groups', () => {
     it('fetches groups', done => {
       const query = 'dummy query';