Officially support the system tray on Windows

ts/test-node/app/SystemTrayService_test.ts

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+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+import * as sinon from 'sinon';
+import { BrowserWindow, MenuItem, Tray } from 'electron';
+import * as path from 'path';
+
+import { SystemTrayService } from '../../../app/SystemTrayService';
+
+describe('SystemTrayService', () => {
+  let sandbox: sinon.SinonSandbox;
+
+  /**
+   * Instantiating an Electron `Tray` has side-effects that we need to clean up. Make sure
+   * to use `newService` instead of `new SystemTrayService` in these tests to ensure that
+   * the tray is cleaned up.
+   *
+   * This only affects these tests, not the "real" code.
+   */
+  function newService(): SystemTrayService {
+    const result = new SystemTrayService({
+      messages: {
+        hide: { message: 'Hide' },
+        quit: { message: 'Quit' },
+        show: { message: 'Show' },
+        signalDesktop: { message: 'Signal' },
+      },
+    });
+    servicesCreated.add(result);
+    return result;
+  }
+
+  const servicesCreated = new Set<SystemTrayService>();
+
+  beforeEach(() => {
+    sandbox = sinon.createSandbox();
+  });
+
+  afterEach(() => {
+    sandbox.restore();
+
+    servicesCreated.forEach(service => {
+      service._getTray()?.destroy();
+    });
+    servicesCreated.clear();
+  });
+
+  it("doesn't render a tray icon unless (1) we're enabled (2) there's a browser window", () => {
+    const service = newService();
+    assert.isUndefined(service._getTray());
+
+    service.setEnabled(true);
+    assert.isUndefined(service._getTray());
+
+    service.setMainWindow(new BrowserWindow({ show: false }));
+    assert.instanceOf(service._getTray(), Tray);
+
+    service.setEnabled(false);
+    assert.isUndefined(service._getTray());
+  });
+
+  it('renders a "Hide" button when the window is shown and a "Show" button when the window is hidden', () => {
+    // We don't actually want to show a browser window. It's disruptive when you're
+    //   running tests and can introduce test-only flakiness. We jump through some hoops
+    //   to fake the behavior.
+    let fakeIsVisible = false;
+    const browserWindow = new BrowserWindow({ show: fakeIsVisible });
+    sinon.stub(browserWindow, 'isVisible').callsFake(() => fakeIsVisible);
+    sinon.stub(browserWindow, 'show').callsFake(() => {
+      fakeIsVisible = true;
+      browserWindow.emit('show');
+    });
+    sinon.stub(browserWindow, 'hide').callsFake(() => {
+      fakeIsVisible = false;
+      browserWindow.emit('hide');
+    });
+
+    const service = newService();
+    service.setEnabled(true);
+    service.setMainWindow(browserWindow);
+
+    const tray = service._getTray();
+    if (!tray) {
+      throw new Error('Test setup failed: expected a tray');
+    }
+
+    // Ideally, there'd be something like `tray.getContextMenu`, but that doesn't exist.
+    //   We also can't spy on `Tray.prototype.setContextMenu` because it's not defined
+    //   that way. So we spy on the specific instance, just to get the context menu.
+    const setContextMenuSpy = sandbox.spy(tray, 'setContextMenu');
+    const getToggleMenuItem = (): undefined | null | MenuItem =>
+      setContextMenuSpy.lastCall?.firstArg?.getMenuItemById(
+        'toggleWindowVisibility'
+      );
+
+    browserWindow.show();
+    assert.strictEqual(getToggleMenuItem()?.label, 'Hide');
+
+    getToggleMenuItem()?.click();
+    assert.strictEqual(getToggleMenuItem()?.label, 'Show');
+
+    getToggleMenuItem()?.click();
+    assert.strictEqual(getToggleMenuItem()?.label, 'Hide');
+  });
+
+  it('destroys the tray when disabling', () => {
+    const service = newService();
+    service.setEnabled(true);
+    service.setMainWindow(new BrowserWindow({ show: false }));
+
+    const tray = service._getTray();
+    if (!tray) {
+      throw new Error('Test setup failed: expected a tray');
+    }
+
+    assert.isFalse(tray.isDestroyed());
+
+    service.setEnabled(false);
+
+    assert.isTrue(tray.isDestroyed());
+  });
+
+  it('maintains the same Tray instance when switching browser window instances', () => {
+    const service = newService();
+    service.setEnabled(true);
+    service.setMainWindow(new BrowserWindow({ show: false }));
+
+    const originalTray = service._getTray();
+
+    service.setMainWindow(new BrowserWindow({ show: false }));
+
+    assert.strictEqual(service._getTray(), originalTray);
+  });
+
+  it('removes browser window event listeners when changing browser window instances', () => {
+    const firstBrowserWindow = new BrowserWindow({ show: false });
+
+    const showListenersAtStart = firstBrowserWindow.listenerCount('show');
+    const hideListenersAtStart = firstBrowserWindow.listenerCount('hide');
+
+    const service = newService();
+    service.setEnabled(true);
+    service.setMainWindow(firstBrowserWindow);
+
+    assert.strictEqual(
+      firstBrowserWindow.listenerCount('show'),
+      showListenersAtStart + 1
+    );
+    assert.strictEqual(
+      firstBrowserWindow.listenerCount('hide'),
+      hideListenersAtStart + 1
+    );
+
+    service.setMainWindow(new BrowserWindow({ show: false }));
+
+    assert.strictEqual(
+      firstBrowserWindow.listenerCount('show'),
+      showListenersAtStart
+    );
+    assert.strictEqual(
+      firstBrowserWindow.listenerCount('hide'),
+      hideListenersAtStart
+    );
+  });
+
+  it('removes browser window event listeners when removing browser window instances', () => {
+    const browserWindow = new BrowserWindow({ show: false });
+
+    const showListenersAtStart = browserWindow.listenerCount('show');
+    const hideListenersAtStart = browserWindow.listenerCount('hide');
+
+    const service = newService();
+    service.setEnabled(true);
+    service.setMainWindow(browserWindow);
+
+    assert.strictEqual(
+      browserWindow.listenerCount('show'),
+      showListenersAtStart + 1
+    );
+    assert.strictEqual(
+      browserWindow.listenerCount('hide'),
+      hideListenersAtStart + 1
+    );
+
+    service.setMainWindow(undefined);
+
+    assert.strictEqual(
+      browserWindow.listenerCount('show'),
+      showListenersAtStart
+    );
+    assert.strictEqual(
+      browserWindow.listenerCount('hide'),
+      hideListenersAtStart
+    );
+  });
+
+  it('updates the icon when the unread count changes', () => {
+    const service = newService();
+    service.setEnabled(true);
+    service.setMainWindow(new BrowserWindow({ show: false }));
+
+    const tray = service._getTray();
+    if (!tray) {
+      throw new Error('Test setup failed: expected a tray');
+    }
+
+    // Ideally, there'd be something like `tray.getImage`, but that doesn't exist. We also
+    //   can't spy on `Tray.prototype.setImage` because it's not defined that way. So we
+    //   spy on the specific instance, just to get the image.
+    const setContextMenuSpy = sandbox.spy(tray, 'setImage');
+    const getImagePath = (): string => {
+      const result = setContextMenuSpy.lastCall?.firstArg;
+      if (!result) {
+        throw new Error('Expected tray.setImage to be called at least once');
+      }
+      return result;
+    };
+
+    for (let i = 9; i >= 1; i -= 1) {
+      service.setUnreadCount(i);
+      assert.strictEqual(path.parse(getImagePath()).base, `${i}.png`);
+    }
+
+    for (let i = 10; i < 13; i += 1) {
+      service.setUnreadCount(i);
+      assert.strictEqual(path.parse(getImagePath()).base, '10.png');
+    }
+
+    service.setUnreadCount(0);
+    assert.match(path.parse(getImagePath()).base, /^icon_\d+\.png$/);
+  });
+});