Testing that button starts an Activity with Robolectric

Question

Hi I have the following code:

@RunWith(Test9Runner.class)
public class MainActivityTest 
{
    private MainActivity activity;
    private Button pressMeButton;

    @Before
    public void setUp() throws Exception 
    {
        activity = new MainActivity();
        activity.onCreate(null);
        pressMeButton = (Button) activity.findViewById(R.id.button1);
    }

    @Test
    public void shouldUpdateResultsWhenButtonIsClicked() throws Exception 
    {
        pressMeButton.performClick();
        ShadowActivity shadowActivity = shadowOf(activity);
        Intent intent = shadowActivity.getResultIntent();
        System.out.print(intent.toString());
    }
}

But I have no idea how to test that pressing pressMeButton started a new Activity. Actually it does, but how to write the correct Robolectric unit test for this fact?

Answer 1

Use Robolectric's StartedMatcher

@RunWith(Test9Runner.class) 
public class MainActivityTest  {
    private MainActivity activity;
    private Button pressMeButton;

    @Before
    public void setUp() throws Exception 
    {
        activity = new MainActivity();
        activity.onCreate(null);
        pressMeButton = (Button) activity.findViewById(R.id.button1);
    }

    @Test
    public void shouldStartNextActivityWhenButtonIsClicked() 
    {
        pressMeButton.performClick();
        assertThat(activity, new StartedMatcher(NextActivity.class));
    }  
}