Function mockRequestIdleCallback

packages/core/test/acceptance/defer_spec.ts:788–794

(
        callback: IdleRequestCallback,
        options?: IdleRequestOptions,
      )

      const idleCallbacks: IdleRequestCallback[] = [];
      const mockRequestIdleCallback = (
        callback: IdleRequestCallback,
        options?: IdleRequestOptions,
      ): number => {
        idleCallbacks.push(callback);
        return 1;
      };

      const nativeRequestIdleCallback = globalThis.requestIdleCallback;
      const nativeCancelIdleCallback = globalThis.cancelIdleCallback;