public function testPop()
{
$col = new Collection();
$this->assertNull($col->pop(), 'pop() returns null on an empty collection');
$data = array('bar1', 'bar2', 'bar3');
$col = new Collection($data);
$this->assertEquals('bar3', $col->pop(), 'pop() returns the last element of the collection');
$this->assertEquals(array('bar1', 'bar2'), $col->getData(), 'pop() removes the last element of the collection');
}