偶发 Bug 怎样用日志、时间线和最小复现缩小范围

let cache = { value: null, expiresAt: 0 };

export async function getCatalog() {
  if (Date.now() >= cache.expiresAt) {
    const value = await loadCatalogFromUpstream();
    cache = { value, expiresAt: Date.now() + 60_000 };
  }
  return cache.value;
}

cache.expiresAt = 0;
upstream.reset({ maxConcurrent: 1, delayMs: 80 });

const results = await Promise.allSettled(
  Array.from({ length: 20 }, () => getCatalog())
);

expect(upstream.calls).toBe(1);
expect(results.every(x => x.status === 'fulfilled')).toBe(true);

let cache = { value: null, expiresAt: 0 };
let refreshPromise = null;

export async function getCatalog() {
  if (Date.now() < cache.expiresAt) return cache.value;

  if (!refreshPromise) {
    refreshPromise = loadCatalogFromUpstream()
      .then(value => {
        cache = { value, expiresAt: Date.now() + 60_000 };
        return value;
      })
      .finally(() => { refreshPromise = null; });
  }

  return refreshPromise;
}