Prevent display sleep while on a call

ts/test-node/app/PreventDisplaySleepService_test.ts

@@ -0,0 +1,104 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+import * as sinon from 'sinon';
+import type { PowerSaveBlocker } from 'electron';
+
+import { PreventDisplaySleepService } from '../../../app/PreventDisplaySleepService';
+
+describe('PreventDisplaySleepService', () => {
+  class FakePowerSaveBlocker implements PowerSaveBlocker {
+    private nextId = 0;
+    private idsStarted = new Set<number>();
+
+    isStarted(id: number): boolean {
+      return this.idsStarted.has(id);
+    }
+
+    start(type: 'prevent-app-suspension' | 'prevent-display-sleep'): number {
+      assert.strictEqual(type, 'prevent-display-sleep');
+
+      const result = this.nextId;
+      this.nextId += 1;
+      this.idsStarted.add(result);
+      return result;
+    }
+
+    stop(id: number): void {
+      assert(this.idsStarted.has(id), `${id} was never started`);
+      this.idsStarted.delete(id);
+    }
+
+    // This is only for testing.
+    _idCount(): number {
+      return this.idsStarted.size;
+    }
+  }
+
+  let sandbox: sinon.SinonSandbox;
+  let powerSaveBlocker: FakePowerSaveBlocker;
+  let service: PreventDisplaySleepService;
+
+  beforeEach(() => {
+    sandbox = sinon.createSandbox();
+    powerSaveBlocker = new FakePowerSaveBlocker();
+    service = new PreventDisplaySleepService(powerSaveBlocker);
+  });
+
+  afterEach(() => {
+    sandbox.restore();
+  });
+
+  it('does nothing if disabling when it was already disabled', () => {
+    const startStub = sandbox.stub(powerSaveBlocker, 'start');
+    const stopStub = sandbox.stub(powerSaveBlocker, 'stop');
+
+    service.setEnabled(false);
+
+    assert.strictEqual(powerSaveBlocker._idCount(), 0);
+    sinon.assert.notCalled(startStub);
+    sinon.assert.notCalled(stopStub);
+  });
+
+  it('can start power blocking', () => {
+    service.setEnabled(true);
+
+    assert.strictEqual(powerSaveBlocker._idCount(), 1);
+  });
+
+  it('only starts power blocking once', () => {
+    service.setEnabled(true);
+    service.setEnabled(true);
+    service.setEnabled(true);
+
+    assert.strictEqual(powerSaveBlocker._idCount(), 1);
+  });
+
+  it('can start and stop power blocking', () => {
+    const startSpy = sandbox.spy(powerSaveBlocker, 'start');
+    const stopStub = sandbox.spy(powerSaveBlocker, 'stop');
+
+    service.setEnabled(true);
+    service.setEnabled(false);
+
+    assert.strictEqual(powerSaveBlocker._idCount(), 0);
+    sinon.assert.calledOnce(startSpy);
+    sinon.assert.calledOnce(stopStub);
+  });
+
+  it('can toggle power blocking several times', () => {
+    const startSpy = sandbox.spy(powerSaveBlocker, 'start');
+    const stopStub = sandbox.spy(powerSaveBlocker, 'stop');
+
+    service.setEnabled(true);
+    service.setEnabled(false);
+    service.setEnabled(true);
+    service.setEnabled(false);
+    service.setEnabled(true);
+
+    assert.strictEqual(powerSaveBlocker._idCount(), 1);
+    sinon.assert.calledThrice(startSpy);
+    sinon.assert.calledTwice(stopStub);
+  });
+});