@Override
  public void dispose() {
    mDisposable.dispose();
  }
@Test
  public void testDispose() {
    DefaultSkinTonePrefTracker tracker =
        new DefaultSkinTonePrefTracker(AnyApplication.prefs(getApplicationContext()));
    Assert.assertFalse(tracker.isDisposed());

    Assert.assertNull(tracker.getDefaultSkinTone());
    SharedPrefsHelper.setPrefsValue(R.string.settings_key_default_emoji_skin_tone, "type_2");
    Assert.assertEquals(JavaEmojiUtils.SkinTone.Fitzpatrick_2, tracker.getDefaultSkinTone());

    tracker.dispose();
    Assert.assertTrue(tracker.isDisposed());

    SharedPrefsHelper.setPrefsValue(R.string.settings_key_default_emoji_skin_tone, "type_3");
    // does not change
    Assert.assertEquals(JavaEmojiUtils.SkinTone.Fitzpatrick_2, tracker.getDefaultSkinTone());
  }