public function generate_uuid()
 {
     for (;;) {
         $uuid = \ICanBoogie\generate_uuid_v4();
         if (!$this->filter_by_uuid($uuid)->count) {
             return $uuid;
         }
     }
 }
 public function test_alter_persistent_properties()
 {
     $responses = array(\ICanBoogie\generate_uuid_v4() => 1, \ICanBoogie\generate_uuid_v4() => 2, \ICanBoogie\generate_uuid_v4() => 3);
     $result = AlterPeristentPropertiesCase::from(array('nid' => 1, 'uid' => 1, 'responses' => $responses));
     $properties = $result->save();
     $this->assertArrayNotHasKey('responses', $properties);
     $this->assertArrayHasKey('serialized_responses', $properties);
     $this->assertSame($properties['serialized_responses'], serialize($responses));
     $this->assertArrayHasKey('created_at', $properties);
     $this->assertArrayHasKey('updated_at', $properties);
     $this->assertInstanceOf('ICanBoogie\\DateTime', $properties['created_at']);
     $this->assertInstanceOf('ICanBoogie\\DateTime', $properties['updated_at']);
     $this->assertFalse($properties['created_at']->is_empty);
     $this->assertFalse($properties['updated_at']->is_empty);
 }