public function testMakeFieldReadonly() { $FieldList = new FieldList(new TabSet('Root', new Tab('Main', new TextField('A'), new TextField('B')))); $FieldList->makeFieldReadonly('A'); $this->assertTrue($FieldList->dataFieldByName('A')->isReadonly(), 'Field nested inside a TabSet and FieldList can be marked readonly by FieldList->makeFieldReadonly()'); }