Question

I’ve got an application that performs HTTP GET calls using HttpGet and I would like to mock the response in order to test different scenarios without having to setup any specific local server that would act like the remote one.

The goal is to have very high level tests that acts like a real user (Robotium) and fake the response that the application would obtain calling the real server. Much like testing a Twitter client, if you need an example.

Answer 1

Ok, so this is what I did to get fake HttpResponses in my Robotium tests:
– I have a class HttpCallBuilder, that usually just returns a DefaultHttpClient
– I added a setHttpClient() method to set a MockHttpClient in my tests (you need to implement (empty) a lot of methods in the HttpClient interface, which I omitted here):

public class MockHttpClient implements HttpClient {

private static Context context;
private final BasicHttpParams params = new BasicHttpParams();

@Override
public HttpResponse execute(HttpUriRequest request) throws IOException,
        ClientProtocolException {
    InputStream mockInputStream = context.getAssets().open(
            MockResponses.forRequest(request));
    return new MockHttpResponse(mockInputStream);
}

@Override
public HttpParams getParams() {
    return params;
}

public static void setContext(Context applicationContext) {
    MockHttpClient.context = applicationContext;
}
}

MockResponses allows you to prime your Mock with the right responses for the situation:

public class MockResponses {

private static final List<String[]> responseMapping = new ArrayList<String[]>();
private static final String BASE = "mocks/";

public static String forRequest(final HttpUriRequest request) {
    final String requestString = request.getURI().toString();
    for (final String[] mapping : responseMapping) {
        if (requestString.matches(mapping[0])) {
            return BASE + mapping[1];
        }
    }
    throw new IllegalArgumentException(
            "No mocked reply configured for request: " + requestString);
}

public static void forRequestDoAnswer(final String regex,
        final String fileToReturn) {
    responseMapping.add(new String[] { regex, fileToReturn });
}

public static void reset() {
    responseMapping.clear();
}
}

In your test you can then prepare your test like this:

HttpCallBuilder.setHttpClient(new MockHttpClient());
MockHttpClient.setContext(context);
MockResponses.reset();
MockResponses.forRequestDoAnswer(".*method=Login.*", "loginform.html");