test: check for apns-id in response

Author: RedPhoenixQ

test/client.js

@@ -356,6 +356,62 @@ describe('Client', () => {
     expect(errorMessages).to.be.empty;
   });
 
+  it('Returns APNs notification ID in responses', async () => {
+    let didRequest = false;
+    let establishedConnections = 0;
+    let requestsServed = 0;
+    const method = HTTP2_METHOD_POST;
+    const path = PATH_DEVICE;
+    const notificationId = '7dc35f9f-58d4-40dd-8c08-38ab811f57df';
+    const additionalHeaderInfo = { 'apns-id': notificationId };
+    server = createAndStartMockServer(TEST_PORT, (req, res, requestBody) => {
+      expect(req.headers).to.deep.equal({
+        ':authority': '127.0.0.1',
+        ':method': method,
+        ':path': path,
+        ':scheme': 'https',
+        'apns-someheader': 'somevalue',
+      });
+      expect(requestBody).to.equal(MOCK_BODY);
+      // res.setHeader('X-Foo', 'bar');
+      // res.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' });
+      res.writeHead(200, additionalHeaderInfo);
+      res.end('');
+      requestsServed += 1;
+      didRequest = true;
+    });
+    server.on('connection', () => (establishedConnections += 1));
+    await new Promise(resolve => server.on('listening', resolve));
+
+    client = createClient(CLIENT_TEST_PORT);
+
+    const runSuccessfulRequest = async () => {
+      const mockHeaders = { 'apns-someheader': 'somevalue' };
+      const mockNotification = {
+        headers: mockHeaders,
+        body: MOCK_BODY,
+      };
+      const device = MOCK_DEVICE_TOKEN;
+      const result = await client.write(mockNotification, device, 'device', 'post');
+      expect(result).to.deep.equal({ ...additionalHeaderInfo, device });
+      expect(didRequest).to.be.true;
+    };
+    expect(establishedConnections).to.equal(0); // should not establish a connection until it's needed
+    // Validate that when multiple valid requests arrive concurrently,
+    // only one HTTP/2 connection gets established
+    await Promise.all([
+      runSuccessfulRequest(),
+      runSuccessfulRequest(),
+      runSuccessfulRequest(),
+      runSuccessfulRequest(),
+      runSuccessfulRequest(),
+    ]);
+    didRequest = false;
+    await runSuccessfulRequest();
+    expect(establishedConnections).to.equal(1); // should establish a connection to the server and reuse it
+    expect(requestsServed).to.equal(6);
+  });
+
   // https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/handling_notification_responses_from_apns
   it('JSON decodes HTTP 400 responses', async () => {
     let didRequest = false;