1 files changed, 113 insertions, 0 deletions
diff --git a/spec/frontend/commons/nav/user_merge_requests_spec.js b/spec/frontend/commons/nav/user_merge_requests_spec.js
new file mode 100644
index 00000000000..4da6d53557a
--- /dev/null
+++ b/spec/frontend/commons/nav/user_merge_requests_spec.js
@@ -0,0 +1,113 @@
+import {
+  openUserCountsBroadcast,
+  closeUserCountsBroadcast,
+  refreshUserMergeRequestCounts,
+} from '~/commons/nav/user_merge_requests';
+import Api from '~/api';
+
+jest.mock('~/api');
+
+const TEST_COUNT = 1000;
+const MR_COUNT_CLASS = 'merge-requests-count';
+
+describe('User Merge Requests', () => {
+  let channelMock;
+  let newBroadcastChannelMock;
+
+  beforeEach(() => {
+    global.gon.current_user_id = 123;
+
+    channelMock = {
+      postMessage: jest.fn(),
+      close: jest.fn(),
+    };
+    newBroadcastChannelMock = jest.fn().mockImplementation(() => channelMock);
+
+    global.BroadcastChannel = newBroadcastChannelMock;
+    setFixtures(`<div class="${MR_COUNT_CLASS}">0</div>`);
+  });
+
+  const findMRCountText = () => document.body.querySelector(`.${MR_COUNT_CLASS}`).textContent;
+
+  describe('refreshUserMergeRequestCounts', () => {
+    beforeEach(() => {
+      Api.userCounts.mockReturnValue(
+        Promise.resolve({
+          data: { merge_requests: TEST_COUNT },
+        }),
+      );
+    });
+
+    describe('with open broadcast channel', () => {
+      beforeEach(() => {
+        openUserCountsBroadcast();
+
+        return refreshUserMergeRequestCounts();
+      });
+
+      it('updates the top count of merge requests', () => {
+        expect(findMRCountText()).toEqual(TEST_COUNT.toLocaleString());
+      });
+
+      it('calls the API', () => {
+        expect(Api.userCounts).toHaveBeenCalled();
+      });
+
+      it('posts count to BroadcastChannel', () => {
+        expect(channelMock.postMessage).toHaveBeenCalledWith(TEST_COUNT);
+      });
+    });
+
+    describe('without open broadcast channel', () => {
+      beforeEach(() => refreshUserMergeRequestCounts());
+
+      it('does not post anything', () => {
+        expect(channelMock.postMessage).not.toHaveBeenCalled();
+      });
+    });
+  });
+
+  describe('openUserCountsBroadcast', () => {
+    beforeEach(() => {
+      openUserCountsBroadcast();
+    });
+
+    it('creates BroadcastChannel that updates DOM on message received', () => {
+      expect(findMRCountText()).toEqual('0');
+
+      channelMock.onmessage({ data: TEST_COUNT });
+
+      expect(findMRCountText()).toEqual(TEST_COUNT.toLocaleString());
+    });
+
+    it('closes if called while already open', () => {
+      expect(channelMock.close).not.toHaveBeenCalled();
+
+      openUserCountsBroadcast();
+
+      expect(channelMock.close).toHaveBeenCalled();
+    });
+  });
+
+  describe('closeUserCountsBroadcast', () => {
+    describe('when not opened', () => {
+      it('does nothing', () => {
+        expect(channelMock.close).not.toHaveBeenCalled();
+      });
+    });
+
+    describe('when opened', () => {
+      beforeEach(() => {
+        openUserCountsBroadcast();
+      });
+
+      it('closes', () => {
+        expect(channelMock.close).not.toHaveBeenCalled();
+
+        closeUserCountsBroadcast();
+
+        expect(channelMock.close).toHaveBeenCalled();
+      });
+    });
+  });
+});