PDO模拟对象缺少getConnection

模仿PDO对象后:

class AdProvidersTest extends PHPUnit_Framework_TestCase
{
    public function dataProvider()
    {
        $providers =  array (
            array (1, '1st', 'desc_1', 101),
            array (2, '2nd', 'desc_2', 202),
            array (3, '3rd', 'desc_3', 303)
          );
        return $providers;
    }
    /**
     * @dataProvider dataProvider
     */
    public function testAdProviders_getConnection($id, $name, $desc, $account_id)
    {
        $data = array (
            array (
                'id' => $id,
                'name' => $name,
                'desc' => $desc,
                'account_id' => $account_id,
            )
        );
        $stmt = $this->getMock('PDOStatement', array ('execute','fetchAll'));
        $stmt->expects($this->any())
             ->method('execute')
             ->will($this->returnValue(true));
        $stmt->expects($this->any())
             ->method('fetchAll')
             ->will($this->returnValue($data));
        $pdo = $this->getMock('PDO', array('prepare'),
            array('sqlite:dbname=:memory'),'PDOMock_' . uniqid(),true);
        $pdo->expects($this->any())
            ->method('prepare')
            ->will($this->returnValue($stmt));

    }
}

我想用这个函数测试连接:

      function getDbh() 
      {
        if ($this->db === null){
          $this->db = Slim::getInstance()->db;
        }
        return $this->db->getConnection();
      }

，但在使用pdo模拟设置数据库后，当试图获得连接时，我得到这个错误:

PHP Fatal error:  Call to undefined method AdProvidersTest::getMockConnection() in /home/al/adserver/adserver/test/classes/AdProvidersTest.php on line 48

是否有方法将此getConnection函数添加到模拟PDO?