public function testEqualPriority()
{
$queue = new StablePriorityQueue();
$first = '1';
$second = '2';
$queue->insert($first, 1);
$queue->insert($second, 1);
$this->assertFalse($queue->isEmpty(), 'Queue has elements');
$this->assertEquals($first, $queue->extract(), 'First element was inserted before');
$this->assertEquals($second, $queue->extract(), 'Second element was inserted after');
}
