Driving the Activity Lifecycle

Before Robolectric 2.2, most tests created Activities by calling constructors directly, (new MyActivity()) and then manually calling lifecycle methods such as onCreate(). Also widely used were a set of methods in ShadowActivity (for instance ShadowActivity.callOnCreate()) that are precursors to ActivityController.

It was a mess. The ActivityController is a Robolectric API that changes all of this. Its goal is to mimic how Android creates your Activities and drives them through their lifecycle.

ActivityController is a fluent API that was introduced in Robolectric 2.0 and is now required in 2.2. In addition to calling methods like onCreate(), it ensures that the internal state of the Activity is consistent with the lifecycle. This includes attaching the Activity to the Window and making system services like the LayoutInflater available.

What do I do now?

You don't generally create an ActivityController directly. Use Robolectric.buildActivity() to get started. For the most basic of tests where you simply need an initialized Activity, you can often get away with the following line:

Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class).create().get();

This will create a new instance of MyAwesomeActivity and call through the life cycle to onCreate().

Want to check that something happens during onResume() but not onCreate()? Easy!

ActivityController controller = Robolectric.buildActivity(MyAwesomeActivity.class).create().start();
Activity activity = controller.get();
// assert that something hasn't happened
// assert it happened!

Similar methods are included for start(), pause(), stop(), and destroy(). So, if you want to test the full creation lifecycle:

Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class).create().start().resume().visible().get();

You can simulate starting the Activity with an intent:

Intent intent = new Intent(Intent.ACTION_VIEW);
Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class).withIntent(intent).create().get();

... or restore saved instance state:

Bundle savedInstanceState = new Bundle();
Activity activity = Robolectric.buildActivity(MyAwesomeActivity.class)

Check out the ActivityController Java Docs to see more public methods available for your testing needs.

Wait, What's This visible() Nonsense?

Turns out that in a real Android app, the view hierarchy of an Activity is not attached to the Window until sometime after onCreate() is called. Until this happens, the Activity's views do not report as visible. This means you can't click on them (amongst other unexpected behavior). The Activity's hierarchy is attached to the Window on a device or emulator after onPostResume() on the Activity. Rather than make assumptions about when the visibility should be updated, Robolectric puts the power in the developer's hands when writing tests.

So when do you call it? Whenever you're interacting with the views inside the Activity. Methods like Robolectric.clickOn() require that the view is visible and properly attached in order to function. You should call visible() after create().