How to fast forward days for testing purpose

[snawaz]

In our tests, we have some jobs to be executed, say 7d later. How do we fast forward the jobs in the queue so that we can test such scenarios?

Using bull: 3.22.0, we used to do this (written by someone before I joined the team):

async function accelerate(q: Queue<unknown>, deltaMs: number): Promise<void> {
  await new Promise((resolve) => setTimeout(resolve, 300));
  try {
    jest.useFakeTimers("modern").setSystemTime(new Date().getTime() + deltaMs);
    // @ts-expect-error Internal method.
    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
    q.updateDelayTimer();
  } finally {
    jest.useRealTimers();
  }
  await new Promise((resolve) => setTimeout(resolve, 300));
}

This used to work.

Now we're migrating to bullmq: ^1.86.1, so how do we accomplish the same using bullmq?

I"m trying this. But I'm not sure if it's even close to what the above is trying to accomplish! 🤔

async function accelerate(q: Queue<unknown>, deltaMs: number): Promise<void> {
  await new Promise((resolve) => setTimeout(resolve, 300));  // how about this?
  const jobs = await q.getDelayed();                                                                                                                         
  await Promise.all(jobs.map(async (job) => await job.changeDelay(deltaMs)));
  await new Promise((resolve) => setTimeout(resolve, 300));  //how about this?
}

[snawaz]

Turned out. I was almost there. So instead of using deltaMs, I used -deltaMs (i.e use negative value).

async function accelerate(q: Queue<unknown>, deltaMs: number): Promise<void> {
  await new Promise((resolve) => setTimeout(resolve, 300)); // give bullmq time to move jobs 
  const jobs = await q.getDelayed();
  await Promise.all(jobs.map(async (job) => await job.changeDelay(-deltaMs))); // NOTE
  await new Promise((resolve) => setTimeout(resolve, 300)); // give bullmq time to move jobs
}

Well, the sign of deltaMs actually depends on how we pass this value. So here it's:

await accelerate(myQueue, ms("8d")); // I use 1d more so that by this time the job will be executed