Function withFixedNow

test/mailboxStore.test.js:26–34

(now, fn)

}

function withFixedNow(now, fn) {
  const originalNow = Date.now;
  Date.now = () => now;
  try {
    return fn();
  } finally {
    Date.now = originalNow;
  }
}

function inboundRow({ id, type, text, now }) {
  return {