@Test
public void testAuthenticate_oauth2NonAppEngine() throws ServiceUnavailableException {

  when(jwtAuthenticator.authenticate(request)).thenReturn(null);
  when(oauth2Authenticator.authenticate(request)).thenReturn(USER);
  System.setProperty(EnvUtil.ENV_APPENGINE_RUNTIME, "");
  attr.set(Attribute.REQUIRE_APPENGINE_USER, true);
  assertEquals(USER, authenticator.authenticate(request));
}