public function testGetPrivateProperty()
 {
     $obj = new BaseClass();
     $this->assertEquals('Private property default value of BaseClass', $obj->getPrivateProperty());
     $obj = new SubClass();
     $this->assertEquals('Private property default value of BaseClass', $obj->getPrivateProperty());
     $obj = new SubClass();
     $this->assertEquals('Private property default value of SubClass', $obj->getOwnPrivateProperty());
 }