Mock Scala.js classes

I'm trying to test React component written in Scala.js, which fetches list of categories from the server. I was able to provide alternative jQuery instance to the component, but jQuery mock itself cannot be compiled. Here is mock's code:

import org.scalajs.jquery.{JQueryXHR, JQueryStatic}

import scala.scalajs.js
import utest._

class jQueryMock extends JQueryStatic {

  var awaitedRequests = Map.empty[String, PartialFunction[js.Any, js.Any]]

  def whenGet(url: String)(response: PartialFunction[js.Any, js.Any]): Unit = {
    awaitedRequests += (url -> response)
  }

  override def get(url: String, data: js.Any, success: js.Any, dataType: js.Any): JQueryXHR = {
    awaitedRequests.get(url) match {
      case Some(response) =>
        if(response.isDefinedAt(data))
          success.asInstanceOf[(js.Any) => Unit](response(data))
        else
          assert(false)
      case None => assert(false)
    }
    new JQueryXHR {}
  }
}

There are two problems in this code according to Scala.js compiler:

• Warning:(14, 95) Members of traits, classes and objects extending js.Any may only contain members that call js.native. This will be enforced in 1.0.

  override def get(url: String, data: js.Any, success: js.Any, dataType: js.Any): JQueryXHR = {

• Error:(19, 9) Traits, classes and objects extending js.Any may not have inner traits, classes or objects

  new JQueryXHR {}

Is there any other way to mock any native class in Scala.js (or in fact any other way to test backend queries)?

Edit

If I throw out extends JQueryStatic and new JQueryXHR {} and change return type of def get, the class compiles fine. This way I could write jQuery wrapper handling AJAX stuff, which I will be able to mock. This will work, but seems to be an awful lot of trouble. Is there any other way to do this?

I've created tests using my facade and it's mock:

Facade

class Http {
  def get(url: String)(success: (js.UndefOr[js.Any]) => Unit): Unit =
    jQuery.getJSON(url, js.undefined, success)
}

Mock

class HttpMock extends Http {

  var awaitedRequests = Map.empty[String, js.Any]

  def whenGet(url: String, response: js.Any): Unit = {
    awaitedRequests += (url -> response)
  }

  def verifyNoOutstandingRequests() =
    assert(awaitedRequests.isEmpty)

  override def get(url: String)(success: (js.UndefOr[js.Any]) => Unit): Unit = {
    awaitedRequests.get(url) match {
      case Some(response) =>
          success(response)
          awaitedRequests -= url
      case None => assert(false)
    }
  }
}