public function testDisableAndEnable()
 {
     // both should mark cache unknown
     $this->obj1->setMetadata($this->name, $this->value);
     $this->obj1->disableMetadata($this->name);
     $this->assertFalse($this->cache->isKnown($this->guid1, $this->name));
     $this->cache->save($this->guid1, $this->name, $this->value);
     $this->obj1->enableMetadata($this->name);
     $this->assertFalse($this->cache->isKnown($this->guid1, $this->name));
 }