test/helpers/poll.ts

export type PollOptions = {
  timeoutMs?: number;
  intervalMs?: number;
};

function sleep(ms: number) {
  return new Promise<void>((resolve) => setTimeout(resolve, ms));
}

export async function pollUntil<T>(
  fn: () => Promise<T | null | undefined>,
  opts: PollOptions = {},
): Promise<T | undefined> {
  const timeoutMs = opts.timeoutMs ?? 2000;
  const intervalMs = opts.intervalMs ?? 25;
  const start = Date.now();

  while (Date.now() - start < timeoutMs) {
    const value = await fn();
    if (value !== null && value !== undefined) {
      return value;
    }
    await sleep(intervalMs);
  }

  return undefined;
}