Espresso: Save and restore state

Do you save and restore state of your activities, fragments and custom views? Do you test them?

One way to test saving and restoring state is to rotate the screen in your Espresso test.

private void rotateScreen() {
  Context context = InstrumentationRegistry.getTargetContext();
  int orientation 
    = context.getResources().getConfiguration().orientation;

  Activity activity = activityRule.getActivity();
  activity.setRequestedOrientation(
      (orientation == Configuration.ORIENTATION_PORTRAIT) ?
          ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE : 
          ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}

With this helper function, you can write tests like this:

@Test
public void incrementTwiceAndRotateScreen() {
  onView(withId(R.id.count))
      .check(matches(withText("0")));

  onView(withId(R.id.increment_button))
      .perform(click(), click());
  onView(withId(R.id.count))
      .check(matches(withText("2")));

  rotateScreen();

  onView(withId(R.id.count))
      .check(matches(withText("2")));
}

Source code

https://github.com/chiuki/espresso-samples/ under rotate-screen

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