Unable to get activity in Unit testing

I am trying to create some tests for my app but for some reasons I am unable to get the activity I want and the test fails. Here is my code:

public class HomeFragmentTest extends ActivityInstrumentationTestCase2<Home>
{
private Home home;
FragmentManager fragmentManager;
RadioGroup radioGroup;

public HomeFragmentTest() {
    super(Home.class);
}

@Override
protected void setUp() throws Exception
{
    super.setUp();
    setActivityInitialTouchMode(false);

    try
    {

        this.home = getActivity();
        RadioButton buttonZone = (RadioButton)home.findViewById(R.id.tabZoneHome);
        fragmentManager= home.getFragmentManager();
        //fragmentManager.executePendingTransactions();
    }catch (Exception e)
    {
        e.printStackTrace();
    }
}

I don't understand why getActivity() method doesn't work and I keep getting this error:

Reason: 'Instrumentation run failed due to 'java.lang.NullPointerException''

What am I doing wrong? Also is this the right way to get the activity and how to call findviewbyid()?