Why I was getting "Jest has detected the following 1 open handle potentially keeping Jest from exiting: Timeout"

[Isaac]

Not a bug. Just wanted to document this here in case anyone else comes across the same issue. When running my tests I was getting the below output:

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  Timeout

      41 |      describe("responses", () => {
      42 |              it("should send a 200 response for a valid request", async () => {
    > 43 |                      const response = await request(app).get(
         |                                                          ^
      44 |                              `/api/${apiVersion}${ROUTE_PATHS.PARTNUMBERS}`
      45 |                      );
      46 |                      // console.log(request(app).get("/").serverAddress(app, "/"));

      at Test.serverAddress (node_modules/supertest/lib/test.js:48:35)
      at new Test (node_modules/supertest/lib/test.js:34:14)
      at Object.obj.<computed> [as get] (node_modules/supertest/index.js:43:18)
      at __tests__/controllers/partnumbers.test.ts:43:40
      at __tests__/controllers/partnumbers.test.ts:8:71
      at Object.<anonymous>.__awaiter (__tests__/controllers/partnumbers.test.ts:4:12)
      at Object.<anonymous> (__tests__/controllers/partnumbers.test.ts:42:67)

I couldn't find anything online or in the github related to a 'Timeout' open handle.

I traced the issue to a rate limiting middleware I had made.

const rateLimiter = (req: Request, res: Response, next: NextFunction) => {
	// Get the client's IP address
	const clientIp = req.ip;

	// Check if the client has exceeded the rate limit
	if (requestCounter.has(clientIp)) {
		const requestsMade = requestCounter.get(clientIp);
		if (requestsMade >= REQUESTS_PER_MINUTE) {
			return res.status(429).send("Too Many Requests");
		}
	}

	// Increment the number of requests made by this client
	requestCounter.set(clientIp, (requestCounter.get(clientIp) || 0) + 1);

	// Clear the request count for this client after 1 minute
	const requestTimer = setTimeout(() => {
		requestCounter.delete(clientIp);
		clearInterval(refillTimer); // clear the refill timer, which also prevents unopen handles in tests
	}, 60 * 1000);

	// Refill the bucket by 1 request every second
	const refillTimer = setInterval(() => {
		requestCounter.set(clientIp, Math.max(requestCounter.get(clientIp) - 1, 0));
	}, 1000);

	// Call the next middleware in the chain
	next();

	// Clean up the timers after the middleware has finished
	clearTimeout(requestTimer);
	clearInterval(refillTimer);
};

Without the clearTimeout and clearInterval calls the timers will start running indefinitely, even after the tests have completed, which was leading to the open handle error.

After adding the calls to clear these two timers I no longer experience the issue.