Function buildAuthAssertion

showcase/harness/src/probes/scripts/d5-auth.ts:145–263

(
  opts: AuthAssertionOpts = {},
)

}

export function buildAuthAssertion(
  opts: AuthAssertionOpts = {},
): (page: Page) => Promise<void> {
  const timeout = opts.signOutTimeoutMs ?? POST_SIGN_OUT_TIMEOUT_MS;
  const detectTimeout = opts.detectTimeoutMs ?? SIGN_IN_MOUNT_TIMEOUT_MS;
  const click = opts.click ?? defaultClick;
  return async (page: Page): Promise<void> => {
    // Sign-out button must be visible — both shapes show it after auth.
    try {
      await page.waitForSelector(SIGN_OUT_BUTTON_SELECTOR, {
        state: "visible",
        timeout: detectTimeout,
      });
    } catch {
      throw new Error(
        `auth: sign-out button ${SIGN_OUT_BUTTON_SELECTOR} not visible — demo did not reach authenticated state (idiomatic: sign-in click failed; legacy: demo did not load authenticated)`,
      );
    }

    // Single deadline gates the entire post-sign-out assertion so the
    // total wall-clock STAYS within `timeout` (the previous version
    // had a hardcoded 3s legacy banner-flip wait + 500ms sleep + 2s
    // fill + 2s press + remaining error-poll, all of which could
    // stack to ~15s when the caller asked for 8s — observable
    // contract violation that only surfaced under tight test
    // timeouts).
    const deadline = Date.now() + timeout;
    const remainingMs = (): number => Math.max(0, deadline - Date.now());
    // Idiomatic detection gets the smaller of 3s or the caller's
    // budget — fast-path for a fresh React render. Inner waitForSelector
    // bound to remaining, so a 100ms deadline can't be overshot by a
    // 200ms inner timeout the way the prior 3s-loop-with-200ms-inner
    // could.
    await click(page, SIGN_OUT_BUTTON_SELECTOR);

    const idiomaticBudgetMs = Math.min(3_000, timeout);
    const idiomaticDeadline = Date.now() + idiomaticBudgetMs;
    let signInCardMounted = false;
    while (Date.now() < idiomaticDeadline) {
      const innerTimeout = Math.min(200, idiomaticDeadline - Date.now());
      if (innerTimeout <= 0) break;
      try {
        await page.waitForSelector(SIGN_IN_CARD_SELECTOR, {
          state: "visible",
          timeout: innerTimeout,
        });
        signInCardMounted = true;
        break;
      } catch {
        // Not yet — continue polling.
      }
    }

    if (signInCardMounted) {
      // Idiomatic shape: SignInCard re-mounted. Pass.
      return;
    }