Illuminate\Support\Collection::getCachingIterator PHP Method

    public function getCachingIterator($flags = CachingIterator::CALL_TOSTRING)
    {
        return new CachingIterator($this->getIterator(), $flags);
    }

 public function testCachingIterator()
 {
     $c = new Collection(['foo']);
     $this->assertInstanceOf('CachingIterator', $c->getCachingIterator());
 }