JUnit4 rules with testing support library

The Android Testing Support Library includes a set of JUnit rules to be used with the AndroidJUnitRunner. JUnit rules provide more flexibility and reduce the boilerplate code required in tests.

TestCase objects like ActivityInstrumentationTestCase2 and ServiceTestCase are deprecated in favor of ActivityTestRule or ServiceTestRule.

ActivityTestRule

This rule provides functional testing of a single activity. The activity under test will be launched before each test annotated with @Test and before any method annotated with @Before. It will be terminated after the test is completed and all methods annotated with @After are finished. The activity under test can be accessed during your test by calling ActivityTestRule.getActivity().

The following code snippet demonstrates how to incorporate this rule into your testing logic:

@RunWith(AndroidJUnit4.class)
@LargeTest
public class MyClassTest {
    @Rule
    public ActivityTestRule<MyClass> mActivityRule =
            new ActivityTestRule(MyClass.class);

    @Test
    public void myClassMethod_ReturnsTrue() { ... }
}

ServiceTestRule

This rule provides a simplified mechanism to start up and shut down your service before and after the duration of your test. It also guarantees that the service is successfully connected when starting a service or binding to one. The service can be started or bound using one of the helper methods. It will automatically be stopped or unbound after the test completes and any methods annotated with @After are finished.

@RunWith(AndroidJUnit4.class)
@MediumTest
public class MyServiceTest {
    @Rule
    public final ServiceTestRule mServiceRule = new ServiceTestRule();

    @Test
    public void testWithStartedService() {
        mServiceRule.startService(
            new Intent(InstrumentationRegistry.getTargetContext(),
            MyService.class));

        // Add your test code here.
    }

    @Test
    public void testWithBoundService() {
        IBinder binder = mServiceRule.bindService(
            new Intent(InstrumentationRegistry.getTargetContext(),
            MyService.class));
        MyService service = ((MyService.LocalBinder) binder).getService();
        assertTrue("Service didn't return true",
            service.doSomethingToReturnTrue());
    }
}