public function testUnsetData()
 {
     $data = array('key1' => 'value1', 'key2' => 'value2');
     $this->_model->setData($data);
     // unset one locked
     $this->_model->lockAttribute('key1')->unsetData('key1');
     $this->assertEquals($data, $this->_model->getData());
     // unset all with read only
     $this->_model->setIsReadonly(true)->unsetData();
     $this->assertEquals($data, $this->_model->getData());
     // unset all
     $this->_model->unlockAttributes()->setIsReadonly(false)->unsetData();
     $this->assertEquals(array(), $this->_model->getData());
 }