public function testPreviousEventReferenceAccessorAndMutator()
 {
     $previousEvent = new Event();
     $previousEvent->setName('previous.event');
     $currentEvent = new Event();
     $currentEvent->setName('current.event')->setPrevious($previousEvent);
     $this->assertInstanceOf(Event::class, $currentEvent->getPrevious());
     $this->assertEquals(Str::cast('previous.event'), $currentEvent->getPrevious()->getName());
 }