@Override
  protected void onPostExecute(Void result) {
    pd.dismiss();
    if (signupToast == null) {
      signupToast = Toast.makeText(context, toastMessage, Toast.LENGTH_SHORT);
    } else {
      signupToast.setText(toastMessage);
    }
    signupToast.show();

    if (toastMessage.equals(successMessage)) {
      context.startActivity(new Intent(context, HelloActivity.class));
      ((MainActivity) context).finish();
    }
  }
 @After
 public void tearDown() throws Exception {
   mainActivity.finish();
 }