Junit testing a class which extends WizardPage

I am tasked with trying to create a Junit test suite of a class which extends 'WizardPage'.

  public class PageDataModel extends WizardPage

Every time I try and create an object of this class within my test suit, the value of the page is null. Below is an example of a test I'm trying to execute.

    @Test
public void testEntityNameNotNumber() {
    PageDataModel pageDataModel = new PageDataModel("testing"); 
    pageDataModel.setContents("person");        
    String temp = pageDataModel.getContents();      
    assertEquals("person",temp );
}

Could someone please suggest where I'm wrong. Many thanks.