@Test(expected=UnsuccessfulResponseException.class)
public void exposesFailureIfAssessorSaysTo() throws Exception {

    resp = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_OK, "OK");
    backend.setResponse(resp);
    impl = new FailureExposingHttpClient(backend, new ResponseFailureAssessor() {
        public boolean isFailure(HttpResponse response) {
            return true;
        }
    });
    impl.execute(host, req, ctx);
}