Test a class that involves listener callback inside AsyncTask

I'm trying to test a listener callback that is being triggered inside an AsyncTask,

Listener class :

interface LoaderListener {
    fun onByteSuccess(..., ..., ...)

    fun onByteFailure(..., ...)
}

The class containing AsyncTask :

class Loader {

override fun handleStreamTask(){
        InputStreamHandlingTask(..., ...).execute(byteArray)
    }

private inner class InputStreamHandlingTask constructor(
            internal var ...,
            internal var ...
        ) : AsyncTask<ByteArray, Void, ByteArray>() {

            override fun doInBackground(vararg params: ByteArray): ByteArray? {
                val response = params[0]
                .....
                return response
            }

            override fun onPostExecute(byteArray: ByteArray?) {
                   if (byteArray != null) {
                       listener.onByteSuccess(..., ..., ...)
                   } else {
                       listener.onByteFailure(..., ...)
                   }
            }

        }
}

The test I'm trying to make :

@Test
fun testIfListenerCalled(){
    val loader: Loader = mock()
    val loaderListener: LoaderListener = mock()

    loader.handleStreamTask()

    verify(loaderListener).onByteSuccess(..., ..., ...)
}

The error I'm curently encountering:

Exception in thread ... java.lang.RuntimeException: Method execute in android.os.AsyncTask not mocked. See http://g.co/androidstudio/not-mocked for details. at android.os.AsyncTask.execute(AsyncTask.java)

from Test a class that involves listener callback inside AsyncTask