Add loop counter for full refresh in playlist

public/app/features/playlist/playlist_srv.ts

@@ -4,12 +4,13 @@ import appEvents from 'app/core/app_events';
 import _ from 'lodash';
 import { toUrlParams } from 'app/core/utils/url';
 
-class PlaylistSrv {
+export class PlaylistSrv {
   private cancelPromise: any;
-  private dashboards: any;
+  private dashboards: Array<{ uri: string }>;
   private index: number;
-  private interval: any;
+  private interval: number;
   private startUrl: string;
+  private numberOfLoops = 0;
   isPlaying: boolean;
 
   /** @ngInject */
@@ -20,8 +21,15 @@ class PlaylistSrv {
 
     const playedAllDashboards = this.index > this.dashboards.length - 1;
     if (playedAllDashboards) {
-      window.location.href = this.startUrl;
-      return;
+      this.numberOfLoops++;
+
+      // This does full reload of the playlist to keep memory in check due to existing leaks but at the same time
+      // we do not want page to flicker after each full loop.
+      if (this.numberOfLoops >= 3) {
+        window.location.href = this.startUrl;
+        return;
+      }
+      this.index = 0;
     }
 
     const dash = this.dashboards[this.index];
@@ -46,8 +54,8 @@ class PlaylistSrv {
     this.index = 0;
     this.isPlaying = true;
 
-    this.backendSrv.get(`/api/playlists/${playlistId}`).then(playlist => {
-      this.backendSrv.get(`/api/playlists/${playlistId}/dashboards`).then(dashboards => {
+    return this.backendSrv.get(`/api/playlists/${playlistId}`).then(playlist => {
+      return this.backendSrv.get(`/api/playlists/${playlistId}/dashboards`).then(dashboards => {
         this.dashboards = dashboards;
         this.interval = kbn.interval_to_ms(playlist.interval);
         this.next();

public/app/features/playlist/specs/playlist_srv.test.ts

@@ -0,0 +1,103 @@
+import { PlaylistSrv } from '../playlist_srv';
+
+const dashboards = [{ uri: 'dash1' }, { uri: 'dash2' }];
+
+const createPlaylistSrv = (): [PlaylistSrv, { url: jest.MockInstance<any> }] => {
+  const mockBackendSrv = {
+    get: jest.fn(url => {
+      switch (url) {
+        case '/api/playlists/1':
+          return Promise.resolve({ interval: '1s' });
+        case '/api/playlists/1/dashboards':
+          return Promise.resolve(dashboards);
+        default:
+          throw new Error(`Unexpected url=${url}`);
+      }
+    }),
+  };
+
+  const mockLocation = {
+    url: jest.fn(),
+    search: () => ({}),
+  };
+
+  const mockTimeout = jest.fn();
+  (mockTimeout as any).cancel = jest.fn();
+
+  return [new PlaylistSrv(mockLocation, mockTimeout, mockBackendSrv), mockLocation];
+};
+
+const mockWindowLocation = (): [jest.MockInstance<any>, () => void] => {
+  const oldLocation = window.location;
+  const hrefMock = jest.fn();
+
+  // JSDom defines window in a way that you cannot tamper with location so this seems to be the only way to change it.
+  // https://github.com/facebook/jest/issues/5124#issuecomment-446659510
+  delete window.location;
+  window.location = {} as any;
+
+  // Only mocking href as that is all this test needs, but otherwise there is lots of things missing, so keep that
+  // in mind if this is reused.
+  Object.defineProperty(window.location, 'href', {
+    set: hrefMock,
+    get: hrefMock,
+  });
+  const unmock = () => {
+    window.location = oldLocation;
+  };
+  return [hrefMock, unmock];
+};
+
+describe('PlaylistSrv', () => {
+  let srv: PlaylistSrv;
+  let mockLocationService: { url: jest.MockInstance<any> };
+  let hrefMock: jest.MockInstance<any>;
+  let unmockLocation: () => void;
+  const initialUrl = 'http://localhost/playlist';
+
+  beforeEach(() => {
+    [srv, mockLocationService] = createPlaylistSrv();
+    [hrefMock, unmockLocation] = mockWindowLocation();
+
+    // This will be cached in the srv when start() is called
+    hrefMock.mockReturnValue(initialUrl);
+  });
+
+  afterEach(() => {
+    unmockLocation();
+  });
+
+  it('runs all dashboards in cycle and reloads page after 3 cycles', async () => {
+    await srv.start(1);
+
+    for (let i = 0; i < 6; i++) {
+      expect(mockLocationService.url).toHaveBeenLastCalledWith(`dashboard/${dashboards[i % 2].uri}?`);
+      srv.next();
+    }
+
+    expect(hrefMock).toHaveBeenCalledTimes(2);
+    expect(hrefMock).toHaveBeenLastCalledWith(initialUrl);
+  });
+
+  it('keeps the refresh counter value after restarting', async () => {
+    await srv.start(1);
+
+    // 1 complete loop
+    for (let i = 0; i < 3; i++) {
+      expect(mockLocationService.url).toHaveBeenLastCalledWith(`dashboard/${dashboards[i % 2].uri}?`);
+      srv.next();
+    }
+
+    srv.stop();
+    await srv.start(1);
+
+    // Another 2 loops
+    for (let i = 0; i < 4; i++) {
+      expect(mockLocationService.url).toHaveBeenLastCalledWith(`dashboard/${dashboards[i % 2].uri}?`);
+      srv.next();
+    }
+
+    expect(hrefMock).toHaveBeenCalledTimes(3);
+    expect(hrefMock).toHaveBeenLastCalledWith(initialUrl);
+  });
+});