public function testValid()
 {
     $collection = new DocumentSet();
     $this->assertFalse($collection->valid());
     $collection = new DocumentSet(array('data' => array('value' => 42)));
     $this->assertTrue($collection->valid());
     $resource = new MockResult(array('data' => array()));
     $collection = new DocumentSet(array('model' => $this->_model, 'result' => $resource));
     $this->assertFalse($collection->valid());
     $resource = new MockResult(array('data' => array(array('id' => 1, 'data' => 'data1'))));
     $collection = new DocumentSet(array('model' => $this->_model, 'result' => $resource));
     $this->assertTrue($collection->valid());
 }