Some code to help engineers mock Twitter4J using EasyMock

gistfile1.java

import java.util.ArrayList;
import java.util.List;

import org.easymock.EasyMock;
import org.easymock.IExpectationSetters;
import org.json.JSONArray;
import org.json.JSONObject;

import twitter4j.Paging;
import twitter4j.RateLimitStatus;
import twitter4j.ResponseList;
import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.json.DataObjectFactory;

import com.mycompany.MyService;
import com.mycompany.MyResponse;
 
 
public class TestTwitter4J {
  
  @Autowired
  MyService myService;
  
 /**
   * Builds a Twitter Status Timeline Response given a raw JSON String
   * 
   * @param twitterRawJSONResponse, a user defined JSON String containing tweets
   * @return A {@link ResponseList} containing expected tweets
   * @throws Exception
   */
  @SuppressWarnings("unchecked")
  public static ResponseList<Status> buildUserTimelineResponseList(String twitterRawJSONResponse) throws Exception {
    
    ResponseList<Status> responseList = null;
    JSONArray array = new JSONArray(twitterRawJSONResponse);
    
    final List<Status> list = new ArrayList<Status>();
    
    if (array.length() > 0) {
      for (int x = 0; x < array.length(); x++) {
        JSONObject obj = (JSONObject) array.get(x);
        Status status = DataObjectFactory.createStatus(obj.toString());
        list.add(status);
      }
    }
    // Create a mock {@link ResponseList} that returns the statuses constructed
    // Only mock the toArray method, only one being used
    responseList = EasyMock.createMock(ResponseList.class);
    EasyMock.expect(responseList.toArray(EasyMock.isA(Status[].class))).andDelegateTo(list).anyTimes();
    EasyMock.replay(responseList);
    
    return responseList;
  }
  
  /**
   * Creates a Mock Twitter service, taking an array of JSON responses to
   * recreate the order in which statuses are returned from Twitter
   * 
   * @param twitterJSONResponses
   * @return
   * @throws Exception
   */
  public static Twitter buildMockTwitterService(String[] twitterJSONResponses) throws Exception {
    Twitter ret = EasyMock.createMock(Twitter.class);
    IExpectationSetters<ResponseList<Status>> expectation = EasyMock.expect(ret.getUserTimeline(EasyMock.isA(String.class),
                                                                                                EasyMock.isA(Paging.class)));
                                                                                                
    for (String resp : twitterJSONResponses) {
      expectation.andReturn(buildUserTimelineResponseList(resp)).times(1);
    }
    EasyMock.replay(ret);
    return ret;
  }
  
  @Test
  public void testMyApp() {
    String [] expectedTweetJsons = new String[] { SOME_STATIC_JSON1, SOME_STATIC_JSON2 }
    Twitter mockTwitter = buildMockTwitterService(expectedTweetJsons);
    myService.setTwitter(mockTwitter);
    // Now Twitter4J can work behind the scenes!
    MyResponse res = myService.processUserTimeline();
    Assert.assertTrue(res.isSuccess());
  }
}