Testing that button starts an Activity with Robolectric

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 shouldUpdateResults开发者_C百科WhenButtonIsClicked() 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?

In Robolectric 2.1.1 you can verify if Intent starting new Activity was emitted in following way.

@RunWith(RobolectricTestRunner.class)
public class MyTest {
  private ShadowActivity shadowActivity;
  private MyActivity activity;

  @Before
  public void setup() {
    activity = new MyActivity();
    shadowActivity = Robolectric.shadowOf(activity);        
  }

  @Test
  public shouldStartNewActivityWhenSomething() {
    //Perform activity startup
    //Do some action which starts second activity, for example View::performClick()
    //...
    //Check Intent
    Intent intent = shadowActivity.peekNextStartedActivityForResult().intent;
    assertThat(intent.getStringExtra(MySecondActivity.EXTRA_MESSAGE)).isEqualTo("blebleble");
    assertThat(intent.getComponent()).isEqualTo(new ComponentName(activity, MySecondActivity.class));
  }
}

This is similar to what I am doing. Please note that creating Activity by calling new Activity() will make Robolectric print warnings about creating activity improperly, this probably can be done better...

Updating this for 3.1.2 as the answers above did not work for me:-

    loginButton.callOnClick();

    Intent startedIntent = shadowOf(activity).getNextStartedActivity();
    ShadowIntent shadowIntent = shadowOf(startedIntent);
    assertEquals(NextActivity.class, shadowIntent.getIntentClass()); 

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));
    }  
}

Inspired by @MichK's answer, here is a complete running test using the buildActivity method chain from Robolectric 2.2+:

@Test
public void testStartScheduleActivity() {
    HomeScreenActivity homeActivity = Robolectric.buildActivity(HomeScreenActivity.class).create().start().visible().get();
    ShadowActivity shadowHome = Robolectric.shadowOf(homeActivity);
    Button btnLaunchSchedule = (Button) homeActivity.findViewById(R.id.btnLaunchSchedule);
    Robolectric.clickOn(btnLaunchSchedule);

    assertThat(shadowHome.peekNextStartedActivityForResult().intent.getComponent(), equalTo(new ComponentName(homeActivity, ScheduleActivity.class)));
}

@Before
public void setUp() throws Exception {
    mMainActivity = Robolectric.buildActivity(MainActivity.class)
            .create().start().visible().get();

    shadowActivity =Shadows.shadowOf(mMainActivity);
    hourlyButton = (Button) mMainActivity.findViewById(R.id.hourlyButton);
}
@Test
public void hourlyActivityButtonTest() throws Exception {

   Thread.sleep(5000);
    hourlyButton.performClick();
    Intent intent = shadowActivity.peekNextStartedActivityForResult().intent;
    assertThat(intent.getComponent()).isEqualTo(new ComponentName(mMainActivity, HourlyForecastActivity.class));

}

James Neville's answer works on 4.3. However, I used the AndroidX API, Espresso and Kotlin:

// scenario initialization is done in @Before setUp method, I did it here for brevity
val scenario = ActivityScenario.launch(MainActivity::class.java)

@Test fun test() {
    onView(withId(R.id.button_id)).perform(click())

    scenario.onActivity { activity ->
        val intent = shadowOf(activity).nextStartedActivity
        val shadowIntent = shadowOf(intent)

        assertEquals(SearchResultsActivity::class.java, shadowIntent.intentClass)
    }
}

This is how does it looks like for the Robolectric 3

        // Click on the image view
    mShareLocationImageView.performClick();

    // Check the startActivityForResult for ShareUserLocationActivity has been triggered
    ShadowActivity shadowActivity = Shadows.shadowOf(mChatWindowsActivity);
    Intent intent = shadowActivity.peekNextStartedActivityForResult().intent;
    assertThat(intent).hasComponent(new ComponentName(mChatWindowsActivity, ShareUserLocationActivity.class));