Fetch sender certificates on-demand

ts/test-electron/util/waitForOnline_test.ts

@@ -0,0 +1,51 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+import * as sinon from 'sinon';
+
+import { waitForOnline } from '../../util/waitForOnline';
+
+describe('waitForOnline', () => {
+  function getFakeWindow(): EventTarget {
+    const result = new EventTarget();
+    sinon.stub(result, 'addEventListener');
+    sinon.stub(result, 'removeEventListener');
+    return result;
+  }
+
+  it("resolves immediately if you're online", async () => {
+    const fakeNavigator = { onLine: true };
+    const fakeWindow = getFakeWindow();
+
+    await waitForOnline(fakeNavigator, fakeWindow);
+
+    sinon.assert.notCalled(fakeWindow.addEventListener as sinon.SinonStub);
+    sinon.assert.notCalled(fakeWindow.removeEventListener as sinon.SinonStub);
+  });
+
+  it("if you're offline, resolves as soon as you're online", async () => {
+    const fakeNavigator = { onLine: false };
+    const fakeWindow = getFakeWindow();
+
+    (fakeWindow.addEventListener as sinon.SinonStub)
+      .withArgs('online')
+      .callsFake((_eventName: string, callback: () => void) => {
+        setTimeout(callback, 0);
+      });
+
+    let done = false;
+    const promise = (async () => {
+      await waitForOnline(fakeNavigator, fakeWindow);
+      done = true;
+    })();
+
+    assert.isFalse(done);
+
+    await promise;
+
+    assert.isTrue(done);
+    sinon.assert.calledOnce(fakeWindow.addEventListener as sinon.SinonStub);
+    sinon.assert.calledOnce(fakeWindow.removeEventListener as sinon.SinonStub);
+  });
+});