No meu caso de teste, eu tenho que gravar por 1 hora, no robotium solo.sleep (600000) havia feito o meu trabalho, mas no café expresso estou confuso com o conceito IdlingResource. Tenho que começar a gravar e aguardar algum tempo (dependendo do tipo de teste) 15 minutos, 60 minutos etc.

Código equivalente em robotium

    solo.clickOnView(solo.getView("start_record"));
    solo.sleep(duration * 60 * 1000);
    solo.clickOnView(solo.getView("stop_record"));

Eu tentei usá-lo assim no café expresso

@RunWith(AndroidJUnit4.class)
@SmallTest
public class AaEspressoTest {

private static final String LAUNCHER_ACTIVITY_FULL_CLASSNAME = "com.absd.rec.RecorderActivity";
private static Class<?> launcherActivityClass;
private Solo solo;
private static CoreRecordingTest skyroTestRunner;


private static Class<? extends Activity> activityClass;

static {
    try {
        activityClass = (Class<? extends Activity>) Class.forName(LAUNCHER_ACTIVITY_FULL_CLASSNAME);
    } catch (ClassNotFoundException e) {
        throw new RuntimeException(e);
    }
}

@Rule
public final ActivityTestRule<?> activityRule
        = new ActivityTestRule<>(activityClass);

private IntentServiceIdlingResource idlingResource;

@Before
public void registerIntentServiceIdlingResource() {
    Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
    idlingResource = new IntentServiceIdlingResource(instrumentation.getTargetContext());
    Espresso.registerIdlingResources(idlingResource);
}

@After
public void unregisterIntentServiceIdlingResource() {
    Espresso.unregisterIdlingResources(idlingResource);
}

@Test
public void testHello() throws Exception {

 onView(withId(AaEspressoTest.getId("recorderpage_record"))).perform(click());

    registerIntentServiceIdlingResource();

    onView(withId(AaEspressoTest.getId("recorderpage_stop"))).perform(click());

   }
}

Recurso ocioso

public class IntentServiceIdlingResource implements IdlingResource {
private final Context context;
private ResourceCallback resourceCallback;
public static boolean status = false;

public IntentServiceIdlingResource(Context context) {
    this.context = context;
}

@Override
public String getName() {
    return IntentServiceIdlingResource.class.getName();
}

@Override
public boolean isIdleNow() {
    return getTimer();
}

@Override
public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
    this.resourceCallback = resourceCallback;

}

private static boolean getTimer() {

    new CountDownTimer(5000, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            // Do Nothing
            status = false;
        }

        @Override
        public void onFinish() {             
            status = true;
        }
    };
    return status;
}
}

Exceção:

android.support.test.espresso.IdlingResourceTimeoutException: Wait for [com.adbs.recorder.IntentServiceIdlingResource] to become idle timed out