public function testRemoveSubscriberWithPriorities() {
$eventSubscriber = new TestEventSubscriberWithPriorities();
$this->dispatcher
->addSubscriber($eventSubscriber);
$this
->assertTrue($this->dispatcher
->hasListeners(self::preFoo));
$this->dispatcher
->removeSubscriber($eventSubscriber);
$this
->assertFalse($this->dispatcher
->hasListeners(self::preFoo));
}