when() requires an argument which has to be 'a method call on a mock'

Question

I am writing JUnit Test cases for my Controller class in Spring.In that I am getting a MissingMethodInvocationException saying when() requires an argument which has to be 'a method call on a mock' while invoking mocked object of WebTarget in when().then method.

Here's the code.

@Controller 
public class JobController {   

    WebTarget target = null;   
    ClientConfig config = new ClientConfig();  
    Client client = ClientBuilder.newClient(config);`
    List<ScheduleJob> scheduleJobsList = new ArrayList<ScheduleJob>();

    @RequestMapping(value = "displayScheduledJobs")
    public ModelAndView displayScheduledJobs(@ModelAttribute(value = "Server") Server server) throws JAXBException {

        List<Server> serverList = serverService.getJobServerList(user.getAccountId());
        target = client.target(getBaseURI(server));
        String xml = target.path("rest").path("getScheduledJobs").request().accept(MediaType.APPLICATION_XML).get(String.class);
        if (xml.contains("<scheduleJob>") && xml.contains("</scheduleJob>")){
            //some code
       }
        model.addObject("scheduleJobsList", scheduleJobsList);
        return model;

     }

    private static URI getBaseURI(Server server) {
        if(server.getSecureFlag().equalsIgnoreCase("N")){
            return UriBuilder.fromUri("http://"+server.getServerIp()+":"+server.getServerPort()+"/jobserver").build();
        } else {
            return UriBuilder.fromUri("https://"+server.getServerIp()+":"+server.getServerPort()+"/jobserver").build();
        }
    }
}

Here's my Test Code.

@RunWith(MockitoJUnitRunner.class)
public class JobControllerTest {

    @Mock
    private WebTarget target;

    @Mock
    private ClientConfig config;

    @Mock
    private Client client;

    @Test
    public void testdisplayScheduledJobs() throws JAXBException {

        List<Server> serverList = new ArrayList<Server>();
        Server server = new Server();
        server.setSecureFlag("N");
        serverList.add(server);
        config = new ClientConfig();
        client = ClientBuilder.newClient(config);
        String xml = "<scheduledJobs>" + "</scheduledJobs>";

        when(serverService.getJobServerList(user.getAccountId())).thenReturn(serverList);
        when(client.target(getBaseURI(server))).thenReturn(target);


        when(target.path("rest")).thenReturn(target); //here the error is getting generated
        when(target.path("getScheduledJobs")).thenReturn(target);
        when(target.request()).thenReturn(builder);
        when(builder.accept(MediaType.APPLICATION_XML)).thenReturn(builder);
        when(builder.get(String.class)).thenReturn(xml);

        model = jobController.displayScheduledJobs(server, request);

        assertEquals("displayScheduledJobs", model.getViewName());

    }
}

Please suggest a way out for this

org.mockito.exceptions.misusing.MissingMethodInvocationException: 
when() requires an argument which has to be 'a method call on a mock'.
For example:
  when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
2. inside when() you don't call method on mock but on some other object.

at com.techm.job.administration.console.controller.JobControllerTest.testdisplayScheduledJobs(JobControllerTest.java:309)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
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.InvokeMethod.evaluate(InvokeMethod.java:20)
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)

Answer 1

You are getting the error because of the following line in your code:

client = ClientBuilder.newClient(config);

When you write this statement, it replaces the mock object of client which you have created above with the new Client and hence client will no longer be recognized as a mock by Mockito.

Also, I hope you are creating the mock of builder as you are doing when(builder.accept(MediaType.APPLICATION_XML)).thenReturn(builder);.

In addition, I can't see any @InjectMocks statements. You'll have to create an object of the class you are testing and annotate it with @InjectMocks annotation.

Also, you'll have to initialize your mocks by doing MockitoAnnotations.initMocks(this); in your testdisplayScheduledJobs() method.

Here is a sample code snippet which will give you more insights:

public class Foo {

    @Mock
    private JerseyWebTarget target;

    @Mock
    private Builder requestBuilder;

    @Mock
    private Response serviceResponse;

    @InjectMocks
    private Foo foo = new Foo();

    @Rule
    public ExpectedException thrown = ExpectedException.none();

    @Before
    public void init() {
        MockitoAnnotations.initMocks(this);

        Mockito.when(target.queryParam(Matchers.anyString(), Matchers.anyString()))
                .thenReturn(target);

        Mockito.when(target.queryParam(Matchers.anyString(), Matchers.anyString()))
                .thenReturn(target);

        Mockito.when(target.queryParam(Matchers.anyString(), Matchers.anyString()))
                .thenReturn(target);

        Mockito.when(target.queryParam(Matchers.anyString(), Matchers.anyString()))
                .thenReturn(target);

        Mockito.when(target.request(MediaType.APPLICATION_JSON_TYPE)).thenReturn(
                requestBuilder);
    }

    @Test
    public void testGetData() {
        List<String> responseList = new ArrayList<>();
        responseList.add("foobar");

        Mockito.when(requestBuilder.get(Matchers.eq(Response.class))).thenReturn(serviceResponse);

        Mockito.when(serviceResponse.getStatus()).thenReturn(200);

        Mockito.when(serviceResponse.readEntity(Matchers.any(GenericType.class))).thenReturn(
                responseList);

        List<String> resultList = foo.getData("foo", "bar");

        Mockito.verify(requestBuilder, Mockito.times(1)).get(Matchers.eq(Response.class));
        Mockito.verify(serviceResponse, Mockito.times(1)).getStatus();
        Mockito.verify(serviceResponse, Mockito.times(1)).readEntity(
                Matchers.any(GenericType.class));

        assertNotNull(resultList);
        assertEquals(1, resultList.size());
        assertEquals("true", resultList.get(0).getConfigSetValue());
    }
}