// tests/helpers/timing.mjs
// A timing assertion that tolerates a busy machine without loosening its limit.
//
// Load only ever ADDS time to a run, so the fastest of a few runs is the best
// reading of what the code itself costs. `fastestWithin` measures up to
// `tries` runs and passes as soon as one is under the limit. A real slowness
// is slow every time and still fails; one run slowed by four other test suites
// does not (measured S123 and in wave 2, 2026-10-08: SC #14 red under load
// 95-177, green alone).

/**
 * @param {number} limitMs - the limit; a run must be strictly under it
 * @param {() => Promise<number>} measure - runs once, resolves to its elapsed ms
 * @param {number} [tries=3]
 * @returns {Promise<{ok: boolean, fastest: number, runs: number[]}>}
 */
export async function fastestWithin(limitMs, measure, tries = 3) {
  const runs = [];
  for (let i = 0; i < tries; i++) {
    runs.push(await measure());
    if (runs[runs.length - 1] < limitMs) break;
  }
  const fastest = Math.min(...runs);
  return { ok: fastest < limitMs, fastest, runs };
}