private File loadBackpackFile(String jsonName) throws IOException {
    UiTestUtils.clearBackPack(true);
    InputStream inputStream =
        getInstrumentation().getContext().getResources().getAssets().open(jsonName);
    File backPackFile = new File(backpackFilePath);
    assertFalse("Backpack.json should not exist!", backPackFile.exists());

    byte[] buffer = new byte[inputStream.available()];
    inputStream.read(buffer);

    File targetFile = new File(backpackFilePath);
    OutputStream outStream = new FileOutputStream(targetFile);
    outStream.write(buffer);
    assertTrue("Backpack.json should exist!", backPackFile.exists());
    assertTrue(
        "Backpacked items not deleted!",
        BackPackListManager.getInstance().getBackpack().backpackedScripts.isEmpty());
    return backPackFile;
  }