The core problem is that it moves part of your OO interface into data. With "isTestPage()" you have a method with well-specified outputs. With "page.hasAttrib

The core problem is that it moves part of your OO interface into data. With "isTestPage()" you have a method with well-specified outputs. With "page.hasAttribute('Test')," a load of things become part of the permanent interface of the class: hasAttribute(), the datatype of 'Test,' the content of the field in the constructed argument etc...