Function pollFor

test/playwright/TestUtils.ts:495–542

(page: playwright.Page, evalOrFn: string | (() => MaybeAsync<T>), val: T, preFn?: () => Promise<void>, options?: IPollForOptions<T>)

}

export async function pollFor<T>(page: playwright.Page, evalOrFn: string | (() => MaybeAsync<T>), val: T, preFn?: () => Promise<void>, options?: IPollForOptions<T>): Promise<void> {
  if (!options) {
    options = {};
  }
  options.stack ??= new Error().stack;
  if (preFn) {
    await preFn();
  }
  const result = typeof evalOrFn === 'string' ? await page.evaluate(evalOrFn) : await evalOrFn();

  if (process.env.DEBUG) {
    console.log('pollFor\n  actual: ', JSON.stringify(result), '  expected: ', JSON.stringify(val));
  }

  let equalityCheck: boolean;
  if (options.equalityFn) {
    equalityCheck = options.equalityFn(result as T, val);
  } else {
    equalityCheck = true;
    try {
      deepStrictEqual(result, val);
    } catch (e) {
      equalityCheck = false;
    }
  }

  if (!equalityCheck) {
    if (options.maxDuration === undefined) {
      options.maxDuration = 2000;
    }
    if (options.maxDuration <= 0) {
      deepStrictEqual(result, val, ([
        `pollFor max duration exceeded.`,
        (`Last comparison: ` +
          `${typeof result === 'object' ? JSON.stringify(result) : result} (actual) !== ` +
          `${typeof val === 'object' ? JSON.stringify(val) : val} (expected)`),
        `Stack: ${options.stack}`
      ].join('\n')));
    }
    return new Promise<void>(r => {
      setTimeout(() => r(pollFor(page, evalOrFn, val, preFn, {
        ...options,
        maxDuration: options!.maxDuration! - 10,
        stack: options!.stack
      })), 10);
    });
  }
}

export async function pollForApproximate<T>(page: playwright.Page, marginOfError: number, evalOrFn: string | (() => MaybeAsync<T>), val: T, preFn?: () => Promise<void>, maxDuration?: number, stack?: string): Promise<void> {
  await pollFor(page, evalOrFn, val, preFn, {