public function testRollbackReplacesFile()
 {
     file_put_contents($this->file->getFullPath(), 'second-version');
     $this->file->createVersion();
     $this->logInWithPermission('ADMIN');
     $this->getFileEditForm();
     $this->assertEquals('second-version', file_get_contents($this->file->CurrentVersion()->getFullPath()));
     $form = $this->mainSession->lastPage()->getFormById('Form_ItemEditForm');
     $url = Director::makeRelative($form->getAction()->asString());
     $data = array();
     foreach ($form->_widgets as $widget) {
         $data[$widget->getName()] = $widget->getValue();
     }
     $this->post($url, array_merge($data, array('Replace' => 'rollback', 'PreviousVersion' => 1, 'ReplacementFile' => array())));
     $this->assertEquals('first-version', file_get_contents($this->file->getFullPath()));
     $this->assertEquals(1, DataObject::get_by_id('File', $this->file->ID)->getVersionNumber());
 }