export interface RstestUtilities {
  // ... existing methods ...

  /**
   * Retry callback until it succeeds (doesn't throw) or timeout is reached.
   * If timeout is reached, throws the last error from the callback.
   */
  waitFor<T>(
    callback: WaitForCallback<T>,
    options?: number | WaitForOptions,
  ): Promise<T>

  /**
   * Retry callback until it returns a truthy value or timeout is reached.
   * If timeout is reached, throws an error.
   */
  waitUntil<T>(
    callback: () => T | Promise<T>,
    options?: number | WaitUntilOptions,
  ): Promise<T>
}

interface WaitForOptions {
  timeout?: number   // default: 1000
  interval?: number  // default: 50
}