/**
  * Tests `Collection::reduce`.
  */
 public function testReduce()
 {
     $collection = new DocumentSet();
     $collection->set(array('title' => 'Lorem Ipsum', 'key' => 'value', 'foo' => 'bar'));
     $result = $collection->reduce(function ($memo, $value) {
         return trim($memo . ' ' . $value);
     }, '');
     $expected = 'Lorem Ipsum value bar';
     $this->assertEqual($expected, $result);
 }