DOMPDFModule\View\Strategy\PdfStrategy::attach PHP Method

    public function attach(EventManagerInterface $events, $priority = 1)
    {
        $this->listeners[] = $events->attach(ViewEvent::EVENT_RENDERER, array($this, 'selectRenderer'), $priority);
        $this->listeners[] = $events->attach(ViewEvent::EVENT_RESPONSE, array($this, 'injectResponse'), $priority);
    }

 public function testEventSubscribers()
 {
     $manager = new EventManager();
     $this->assertCount(0, $manager->getListeners(ViewEvent::EVENT_RENDERER), 'Renderer listener before attach');
     $this->assertCount(0, $manager->getListeners(ViewEvent::EVENT_RESPONSE), 'Response listener before attach');
     $this->strategy->attach($manager);
     $this->assertCount(1, $manager->getListeners(ViewEvent::EVENT_RENDERER), 'Renderer listener after attach');
     $this->assertCount(1, $manager->getListeners(ViewEvent::EVENT_RESPONSE), 'Response listener after attach');
     $this->strategy->detach($manager);
     $this->assertCount(0, $manager->getListeners(ViewEvent::EVENT_RENDERER), 'Renderer listener after detach');
     $this->assertCount(0, $manager->getListeners(ViewEvent::EVENT_RESPONSE), 'Response listener after detach');
 }