Jest hangs when publishing to @google-cloud/pubsub in integration test

[gonchantech]

I have an integration test that publishes a domain event to Google Cloud Pub/Sub (using the Pub/Sub emulator). The test itself passes, but Jest never exits.

If I comment out the publishMessage/dispatch call the test exits fine. Removing subscription listeners does not fix the issue, so the problem seems to be on the publisher side.

What happens

• Eventduspatcher.integration.test.ts passes but Jest prints:Jest did not exit one second after the test run has completed. This usually means that there are asynchronous operations that weren't stopped in your tests.
• Commenting out the code that triggers publishing makes the problem disappear.

Key snippets (simplified)

EventDispatcher (simplified)

import { PubSub } from "@google-cloud/pubsub";

export class EventDispatcher {
  constructor(private readonly pubSubClient: PubSub, private readonly topicName: string) {}

  async dispatch(events: any[]): Promise<void> {
    const publishPromises = events.map((event) =>
      this.pubSubClient.topic(this.topicName).publishMessage({
        data: Buffer.from(JSON.stringify(event)),
      })
    );

    await Promise.allSettled(publishPromises);
  }
}

EventDispatcher Test(simplified)

import { EventDispatcher } from "../EventDispatcher";
import { PubSub } from "@google-cloud/pubsub";

describe("EventDispatcher Integration Tests", () => {
  let pubSubClient: PubSub;
  let subscription: any;
  let receivedMessages: any[] = [];

  const topicName = "test-event-dispatcher-topic";
  const subscriptionName = "test-event-dispatcher-subscription";

  beforeAll(async () => {
    pubSubClient = new PubSub({ projectId: "test-project" });

    const topic = pubSubClient.topic(topicName);
    const [exists] = await topic.exists();
    if (!exists) await topic.create();

    subscription = topic.subscription(subscriptionName);
    const [subExists] = await subscription.exists();
    if (!subExists) await subscription.create();
  });

  beforeEach(() => {
    receivedMessages = [];
    subscription.on("message", (message: any) => {
      receivedMessages.push(message);
      message.ack();
    });
  });

  afterEach(() => {
    subscription.removeAllListeners();
  });

  afterAll(async () => {
    await subscription.delete();
    await pubSubClient.topic(topicName).delete();
    // Is there something else I should close here?
  });

  it("should dispatch and receive a message", async () => {
    const dispatcher = new EventDispatcher(pubSubClient, topicName);
    await dispatcher.dispatch([{ type: "UserCreated" }]);

    await new Promise((resolve) => setTimeout(resolve, 1000));
    expect(receivedMessages).toHaveLength(1);
  });
});

What I have tried

1. subscription.removeAllListeners() on the subscriber side (not the cause).
2. In EventDispatcher.dispatch() I added:await pubSubClient.topic(topicName).flush(); await Promise.allSettled(publishPromises); await pubSubClient.close();

and did not made the hang go away.

3. Commenting out the dispatch / publishMessage call: problem disappears.

Notes

• I have some integration tests that uses EventDispatcher.
• Each tests passes (assertions succeed) when running test in a single file
• When running multiple files, the test that runs after another, sometimes receive events that should have been recevied in another file.

Question

How can I solve this issue ?
Doesn't await publishMessage wait until the publish is actually successful?