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ActivityScenario

public final class ActivityScenario
extends Object implements AutoCloseable, Closeable

java.lang.Object
   ↳ androidx.test.core.app.ActivityScenario<A extends android.app.Activity>

ActivityScenario provides APIs to start and drive an Activity's lifecycle state for testing. It works with arbitrary activities and works consistently across different versions of the Android framework.

The ActivityScenario API uses Lifecycle.State extensively. If you are unfamiliar with android.arch.lifecycle components, please read lifecycle before starting. It is crucial to understand the difference between Lifecycle.State and Lifecycle.Event.

moveToState(State) allows you to transition your Activity's state to CREATED, STARTED, RESUMED, or DESTROYED. There are two paths for an Activity to reach CREATED: after ON_CREATE happens but before ON_START, or after ON_STOP. ActivityScenario always moves the Activity's state using the second path. The same applies to STARTED.

DESTROYED is the terminal state. You cannot move your Activity to other state once it reaches to that state. If you want to test recreation of Activity instance, use recreate().

ActivityScenario does't clean up device state automatically and may leave the activity keep running after the test finishes. Call close() in your test to clean up the state or use try-with-resources statement. This is optional but highly recommended to improve the stability of your tests. Also, consider using ActivityScenarioRule.

This class is a replacement of ActivityController in Robolectric and ActivityTestRule in ATSL.

Following are the example of common use cases. 

Before:
   MyActivity activity = Robolectric.setupActivity(MyActivity.class);
   assertThat(activity.getSomething()).isEqualTo("something");

 After:
   try(ActivityScenario<MyActivity> scenario = ActivityScenario.launch(MyActivity.class)) {
     scenario.onActivity(activity -> {
       assertThat(activity.getSomething()).isEqualTo("something");
     });
   }

 Before:
   ActivityController<MyActivity> controller = Robolectric.buildActivity(MyActivity.class);
   controller.create().start().resume();  // Moves the activity state to State.RESUMED.
   controller.pause();    // Moves the activity state to State.STARTED. (ON_PAUSE is an event).
   controller.stop();     // Moves the activity state to State.CREATED. (ON_STOP is an event).
   controller.destroy();  // Moves the activity state to State.DESTROYED.

 After:
   try(ActivityScenario<MyActivity> scenario = ActivityScenario.launch(MyActivity.class)) {
     scenario.moveToState(State.RESUMED);    // Moves the activity state to State.RESUMED.
     scenario.moveToState(State.STARTED);    // Moves the activity state to State.STARTED.
     scenario.moveToState(State.CREATED);    // Moves the activity state to State.CREATED.
     scenario.moveToState(State.DESTROYED);  // Moves the activity state to State.DESTROYED.
   }

Summary

Nested classes

interface ActivityScenario.ActivityAction<A extends Activity>

ActivityAction interface should be implemented by any class whose instances are intended to be executed by the main thread. 

Public methods

void close()

Finishes the managed activity and cleans up device's state.

Instrumentation.ActivityResult getResult()

Waits for the activity to be finished and returns the activity result.

Lifecycle.State getState()

Returns the current activity state.

static <A extends Activity> ActivityScenario<A> launch(Class<A> activityClass)

Launches an activity of a given class and constructs ActivityScenario with the activity.

static <A extends Activity> ActivityScenario<A> launch(Class<A> activityClass, Bundle activityOptions)
static <A extends Activity> ActivityScenario<A> launch(Intent startActivityIntent)

Launches an activity by a given intent and constructs ActivityScenario with the activity.

static <A extends Activity> ActivityScenario<A> launch(Intent startActivityIntent, Bundle activityOptions)
ActivityScenario<A> moveToState(Lifecycle.State newState)

Moves Activity state to a new state.

ActivityScenario<A> onActivity(ActivityAction<A> action)

Runs a given action on the current Activity's main thread.

ActivityScenario<A> recreate()

Recreates the Activity.

Inherited methods

From class java.lang.Object
From interface java.lang.AutoCloseable
From interface java.io.Closeable

Public methods

close

void close ()

Finishes the managed activity and cleans up device's state. This method blocks execution until the activity becomes DESTROYED.

It is highly recommended to call this method after you test is done to keep the device state clean although this is optional.

You may call this method more than once. If the activity has been finished already, this method does nothing.

Avoid calling this method directly. Consider one of the following options instead: 

Option 1, use try-with-resources:

  try (ActivityScenario<MyActivity> scenario = ActivityScenario.launch(MyActivity.class)) {
    // Your test code goes here.
  }

  Option 2, use ActivityScenarioRule:

 @Rule public ActivityScenarioRule<MyActivity> rule = new ActivityScenarioRule<>(MyActivity.class);

 @Testpublic void myTest() {
    ActivityScenario<MyActivity> scenario = rule.getScenario();
    // Your test code goes here.
  }

getResult

Instrumentation.ActivityResult getResult ()

Waits for the activity to be finished and returns the activity result.

Note: This method doesn't call finish(). The activity must be finishing or finished otherwise this method will throws runtime exception after the timeout. 

Example:
   ActivityScenario<MyActivity> scenario = ActivityScenario.launch(MyActivity.class);
   // Let's say MyActivity has a button that finishes itself.
   onView(withId(R.id.finish_button)).perform(click());
   assertThat(scenario.getResult().getResultCode()).isEqualTo(Activity.RESULT_OK);

Returns
Instrumentation.ActivityResult activity result of the activity that managed by this scenario class.

getState

Lifecycle.State getState ()

Returns the current activity state. The possible states are CREATED, STARTED, RESUMED, and DESTROYED.

This method cannot be called from the main thread except in Robolectric tests.

Returns
Lifecycle.State

launch

ActivityScenario<A> launch (Class<A> activityClass)

Launches an activity of a given class and constructs ActivityScenario with the activity. Waits for the lifecycle state transitions to be complete. Typically the initial state of the activity is RESUMED but can be in another state. For instance, if your activity calls finish() from your onCreate(Bundle), the state is DESTROYED when this method returns.

If you need to supply parameters to the start activity intent, use launch(Intent).

This method cannot be called from the main thread except in Robolectric tests.

Parameters
activityClass Class: an activity class to launch
Returns
ActivityScenario<A> ActivityScenario which you can use to make further state transitions

Throws
AssertionError if the lifecycle state transition never completes within the timeout

launch

ActivityScenario<A> launch (Class<A> activityClass, 
                Bundle activityOptions)

Parameters
activityClass Class

activityOptions Bundle: an activity options bundle to be passed along with the intent to start activity.

Returns
ActivityScenario<A>

See also:

launch

ActivityScenario<A> launch (Intent startActivityIntent)

Launches an activity by a given intent and constructs ActivityScenario with the activity. Waits for the lifecycle state transitions to be complete. Typically the initial state of the activity is RESUMED but can be in another state. For instance, if your activity calls finish() from your onCreate(Bundle), the state is DESTROYED when this method returns.

This method cannot be called from the main thread except in Robolectric tests.

Parameters
startActivityIntent Intent: an intent to start the activity
Returns
ActivityScenario<A> ActivityScenario which you can use to make further state transitions

Throws
AssertionError if the lifecycle state transition never completes within the timeout

launch

ActivityScenario<A> launch (Intent startActivityIntent, 
                Bundle activityOptions)

Parameters
startActivityIntent Intent

activityOptions Bundle: an activity options bundle to be passed along with the intent to start activity.

Returns
ActivityScenario<A>

See also:

moveToState

ActivityScenario<A> moveToState (Lifecycle.State newState)

Moves Activity state to a new state.

If a new state and current state are the same, it does nothing. It accepts CREATED, STARTED, RESUMED, and DESTROYED.

DESTROYED is the terminal state. You cannot move the state to other state after the activity reaches that state.

The activity must be at the top of the back stack (excluding internal facilitator activities started by this library), otherwise AssertionError may be thrown. If the activity starts another activity (such as DialogActivity), make sure you close these activities and bring back the original activity foreground before you call this method.

This method cannot be called from the main thread except in Robolectric tests.

Parameters
newState Lifecycle.State

Returns
ActivityScenario<A>

Throws
IllegalArgumentException if unsupported newState is given
IllegalStateException if Activity is destroyed, finished or finishing
AssertionError if Activity never becomes requested state

onActivity

ActivityScenario<A> onActivity (ActivityAction<A> action)

Runs a given action on the current Activity's main thread.

Note that you should never keep Activity reference passed into your action because it can be recreated at anytime during state transitions.

Parameters
action ActivityAction

Returns
ActivityScenario<A>

Throws
IllegalStateException if Activity is destroyed, finished or finishing

recreate

ActivityScenario<A> recreate ()

Recreates the Activity.

A current Activity will be destroyed after its data is saved into Bundle with onSaveInstanceState(Bundle), then it creates a new Activity with the saved Bundle. After this method call, it is ensured that the Activity state goes back to the same state as its previous state.

This method cannot be called from the main thread except in Robolectric tests.

Returns
ActivityScenario<A>

Throws
IllegalStateException if Activity is destroyed, finished or finishing
AssertionError if Activity never be re-created