// mock a request that has custom query, body, and header params set
HttpRequest request = mock(HttpRequest.class);
when(request.getRequestUrl()).thenReturn("http://example.com?a=1");
OAuthMessageSigner signer = mock(HmacSha1MessageSigner.class);
consumer.setMessageSigner(signer);
HttpParameters params = new HttpParameters();
params.put("oauth_callback", "http://mycallback");
consumer.setAdditionalParameters(params);