Mock Jersey Client Request response using Mockito and Junit

Question

I searched on the forum and tried to get some heads up, by experimenting what others have already mentioned in other related posts but nothing worked for me since I am new to mockito junit, hence posting this question.

I have a rest client , which calls Rest webservice :-

// Rest Client code
public static String getProcessString(String url) {
Client client = Client.create();
com.sun.jersey.api.client.WebResource webResource = client.resource(url);
webResource.accept("application/json");
/*if (response.getStatus() != 200) {
       throw new RuntimeException("Failed : HTTP error code : "
        + response.getStatus());
    }*/
String process = webResource.get(String.class);

return process;

}

My plan is to unit test getProcessString(String url) method. My RestClientUnitTest.java code is shown below:-

package......service.workflow.client;

import static org.mockito.Matchers.any;
import static org.mockito.Mockito.doReturn;
import junit.framework.Assert;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.runners.MockitoJUnitRunner;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.WebResource;
@RunWith(MockitoJUnitRunner.class)
public class RestClientUnitTest {
    @InjectMocks
    private  RestClient  RestClient = new  RestClient();

    @Mock
    private com.sun.jersey.api.client.WebResource res;





    @Mock
    private Client client;

    private String URL = "http://localhost:9095/jersey/recoveryservice/fetchUpdateProcesses?oldProcessDefinitionId=maker_checker&newProcessDefinitionId=maker_checker_v1";
    @Before
    public void setUp() throws Exception {
        Client mockClient = Client.create();
        doReturn(mockClient).when(client).create();
        //WebResource webResource = mockClient.resource(URL);
        doReturn(webResource).when(mockClient).resource(URL);
        //when(mockClient.resource(URL)).thenReturn(res);
        doReturn("OK").when(res).get((Class<String>) any());
        //when(webResource.get((Class<String>) any())).thenReturn("OK");

    }

    @Test
    public void testgetProcessString() {
        Assert.assertEquals(RestClient.getProcessString("http://localhost:9095/jersey/recoveryservice/fetchUpdateProcesses?oldProcessDefinitionId=maker_checker&newProcessDefinitionId=maker_checker_v1"), "OK");
        /*Client client = Client.create();
        com.sun.jersey.api.client.WebResource webResource = client.resource(url);
        webResource.accept("application/json");
        if (response.getStatus() != 200) {
               throw new RuntimeException("Failed : HTTP error code : "
                + response.getStatus());
            }
        String process = webResource.get(String.class);

        return process;*/
    }

}

However my unit test is failing at :- doReturn(webResource).when(mockClient).resource(URL); error trace is :-

 org.mockito.exceptions.misusing.UnfinishedStubbingException: 
Unfinished stubbing detected here:
-> at .......service.workflow.client.RestClientUnitTest.setUp(RestClientUnitTest.java:35)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);
    when(mock.isOk()).thenThrow(exception);
    doThrow(exception).when(mock).someVoidMethod();
Hints:
 1. missing thenReturn()
 2. although stubbed methods may return mocks, you cannot inline mock creation (mock()) call inside a thenReturn method (see issue 53)

    at ......service.workflow.client.RestClientUnitTest.setUp(RestClientUnitTest.java:37)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
    at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Not sure what am I missing here? Any ideas and suggestions will be appreciated

After some analysis, tweaked the code in setUp() method as :-

    Client mockClient =Client.create();
    //WebResource mockWebResource = Mockito.mock(WebResource.class);
    //when(client.create()).thenReturn(mockClient);
    doReturn(mockClient).when(client).create();
     res = mockClient.resource(URL);

    when(res.get((Class<String>) any())).thenReturn("OK"); ---> Error
    //stub(res.get((Class<String>) any())).toReturn("OK");

So no more getting the earlier exception, but now it seems trying to actually connect at the URL for webResource.get() and hence giving below error:-

  com.sun.jersey.api.client.ClientHandlerException: java.net.ConnectException: Connection refused: connect
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:148)
    at com.sun.jersey.api.client.Client.handle(Client.java:642)
    at com.sun.jersey.api.client.WebResource.handle(WebResource.java:601)
    at com.sun.jersey.api.client.WebResource.get(WebResource.java:187)
    at ........service.workflow.client.RestClientUnitTest.setUp(RestClientUnitTest.java:52)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)

Answer 1

To your 1st error log: it tells you how you should use the API:

E.g. thenReturn() may be missing.
Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);

To your second error: you call Client mockClient = Client.create(); which is NOT mocking, but calling a real method.

This is how you should do it:

//First you create a mock with an annotation
@Mock
private Client clientMock;

// ...

// Then you define special behaviour, e.g.
when(clientMock.foo()).thenReturn("bar");

// Then you use the mock instance:
assertEquals("bar", clientMock.foo());

However, you are mocking Jersey's Client but you do not set that mocked instance to your RestClient, and therefore it is using the real one. Either you introduce a setter to RestClient which sets the Client instance (which is not very nice), or you get more sophisticated and mock Client.create(), which is a static method and Mockito is not able to mock static methods. Instead you can take a look at PowerMock (which uses Mockito; it still has some limitations) or JMockit (which is a complete and mighty mocking-framework, but documentation is quite short)