private F startFragment(F fragment) {
   FragmentTransaction transaction = mActivity.getFragmentManager().beginTransaction();
   transaction.add(R.id.activity_test_fragment_linearlayout, fragment, "tag");
   transaction.commit();
   getInstrumentation().waitForIdleSync();
   F frag = (F) mActivity.getFragmentManager().findFragmentByTag("tag");
   return frag;
 }