@Test
public void unauthorized() throws Exception {

    MockHttpStack mockHttpStack = new MockHttpStack();
    HttpResponse fakeResponse = new HttpResponse(401, Collections.<Header>emptyList());
    mockHttpStack.setResponseToReturn(fakeResponse);
    BasicNetwork httpNetwork = new BasicNetwork(mockHttpStack);
    Request<String> request = buildRequest();
    request.setRetryPolicy(mMockRetryPolicy);
    doThrow(new VolleyError()).when(mMockRetryPolicy).retry(any(VolleyError.class));
    try {
        httpNetwork.performRequest(request);
    } catch (VolleyError e) {
        // expected
    }
    // should retry in case it's an auth failure.
    verify(mMockRetryPolicy).retry(any(AuthFailureError.class));
}