Something

class a extends Doctrine_Record{
}
class TestY extends a{
    public function setTableDefinition() {
        $this->hasColumn("id","integer",30,array("autoincrement"=>true,"primary"));
    }
}
class TestX extends Doctrine_Record{
    public function setTableDefinition() {
        $this->hasColumn("id","integer",30,array("autoincrement"=>true,"primary"));
    }
    public function setUp(){
        $this->hasOne("TestY","TestY");
    }
}

class Doctrine_Ext extends Doctrine_UnitTestCase
{
    function testE(){

        Doctrine_Manager::getInstance()->getTable("TestX");
    }
}
$test->addTestCase(new Doctrine_Ext());