public function testContainsAllElements()
 {
     $collectionA = new BasicCollection();
     $collectionA->add('foo');
     $collectionA->add('bar');
     $collectionA->add('foo');
     $collectionB = new BasicCollection();
     $collectionB->add('bar');
     $collectionB->add('baz');
     $collectionB->add('foo');
     self::assertTrue($collectionB->containsAll($collectionA));
     self::assertFalse($collectionA->containsAll($collectionB));
 }