[DomCrawler] extract(): fix a bug when the attribute list is empty

Author: dunglas

Crawler.php

@@ -605,7 +605,7 @@ public function extract($attributes)
                 }
             }
 
-            $data[] = $count > 1 ? $elements : $elements[0];
+            $data[] = 1 === $count ? $elements[0] : $elements;
         }
 
         return $data;

Tests/CrawlerTest.php

@@ -369,6 +369,7 @@ public function testExtract()
 
         $this->assertEquals(array('One', 'Two', 'Three'), $crawler->extract('_text'), '->extract() returns an array of extracted data from the node list');
         $this->assertEquals(array(array('One', 'first'), array('Two', ''), array('Three', '')), $crawler->extract(array('_text', 'class')), '->extract() returns an array of extracted data from the node list');
+        $this->assertEquals(array(array(), array(), array()), $crawler->extract(array()), '->extract() returns empty arrays if the attribute list is empty');
 
         $this->assertEquals(array(), $this->createTestCrawler()->filterXPath('//ol')->extract('_text'), '->extract() returns an empty array if the node list is empty');
     }