Contributing "waitFor" function to async module, desired?

[acrodrig]

Very often when writing integration tests I need to wait for a condition to be true to continue (for example the database record is there, or an SMS message has arrived). I use the function below repeatedly and I would love if it can be part of @std/async. If you see value in it, would contribute as PR. Please let know.

/**
 * Wait for a condition to be true, jumping every `jump` milliseconds until 
 * `timeout` is reached. Can be used as:
 *
 * ```typescript
 * let i = 0;
 * const id = setInterval(() => i++, 42);
 * await waitFor(() => i > 10);
 * clearInterval(id);
 * assert(i > 10);
 * ```
 *
 * @param condition - predicate returning a (potentially promised) boolean
 * @param timeout - maximum wait time (default 20s, 0 for infinite)
 * @param jump - the time to wait between checks (default 100ms)
 */
function waitFor(condition: () => boolean | Promise<boolean>, timeout = 20000, jump = 100) {
  // Time we start the checks so that we can
  const start = Date.now();

  return new Promise(function (resolve, reject) {
    // If condition is "truthy" resolve, if timeout reject, otherwise keep waiting
    const check = async function (): Promise<void> {
      const value = await condition();
      if (value) return resolve(value);
      const time = Date.now() - start;
      if (time > timeout) return reject(new Error("Timeout (" + timeout + "ms) waiting for condition!"));
      setTimeout(check, jump);
    };

    // Start checking
    setTimeout(check);
  });
}

[kt3k]

The suggestion looks reasonable to me.

Please add this as unstable feature first. https://github.com/denoland/std/blob/9daae0547ff646dddcd0628afe355b61eace78d5/.github/CONTRIBUTING.md#suggesting-a-new-feature

The error class might better to be DOMException with TimeoutError name, that is what AbortSignal.timeout() and @std/async/deadline throw