How to use isInvokable method of org.mockito.internal.invocation.RealMethod class

The response by david-wallace explains why you run into an OOM: a mock object is remembering details of every invocation.

But an equally important question is: now what to do about it? In addition to what David already suggested, the latest Mockito versions 1.10.19 as well as upcoming 2.0.x now support so-called stubOnly mocks (see javadoc):

stubOnly: A stub-only mock does not record method invocations, thus saving memory but disallowing verification of invocations.

Scala usage example:

import org.mockito.Mockito
val list = Mockito.mock(classOf[Foo], Mockito.withSettings().stubOnly())

// The syntax is a bit more concise when using ScalaTest's MockitoSugar
val foo = mock[Foo](Mockito.withSettings().stubOnly())

Java usage example (untested):

import org.mockito.Mockito;
Foo mock = Mockito.mock(Foo.class, Mockito.withSettings().stubOnly());

This took me a while to figure out, so I am answering my own question.

AFAIK, you need to "undo" each mock. Mockito.reset() will not work with Class<?> references. At the end of the test method, add:

// Undo the mock above because we need to call PathUtils.removeFile() within @After.
PowerMockito.doCallRealMethod().when(PathUtils.class);
PathUtils.removeFile(Mockito.any(File.class));

Mockito mock works when we mock the objects loosely.

Here is the change i have made to make it work:

when(controlWfDefTypeService.getDqCntlWfDefnTypCd(any(DqCntlWfDefn.class))
    .thenReturn(dqCntlWfDefnTyp);

Instead of passing the object of the Mock class, I passed the class with the Matcher any() and it works.

You don't need RETURNS_DEEP_STUBS or whatever that mock annotation is. You just have to mock every object that you want to return in the chain, similar to this:

@Mock Issue issue;
@Mock URI uri;

@Before
public void setup() {
    when(uri.getHost()).thenReturn(JIRA_HOST);
    when(issue.getSelf()).thenReturn(uri);
}

Update July 29, 2015 by @durron597: This excellent answer was correct in 2013, however it has since been rendered obsolete by an update to Mockito. See this answer.

I use latest JUnit with Mockito core dependency and hamcrest 1.3 in many Maven projects at work. Till now nobody reported any problem with this. So if this works for your tests go with the newest Version for all three. Just ensure to use mockito core instead of all.

So I would recommend to go with option 2 to have all benefits of the newer versions. If you are really in doubt that anything could go wrong use option 4 which is the safest one. But of course you could go with option 2 and when in the near future anything would be wrong you could switch to option 2. Or since then a newer mockito is already out there solving this.

Note from mockito Issue 397: This problem does not appear with mockito-core.

For void methods, I think you need to use the doThrow syntax.

So in your case it would be:

doThrow(BookingException.builder().build())
      .when(booking)
      .validate(any());

You simply inject it with the @Context annotation, as a field or method parameter.

@Path("resource")
public class Resource {
    @Context
    UriInfo uriInfo;

    public Response doSomthing(@Context UriInfo uriInfo) {

    }
}

Other than your resource classes, it can also be injected into other providers, like ContainerRequestContext, ContextResolver, MessageBodyReader etc.

EDIT

Actually I want to write a junit test for a function similar to your doSomthing() function.

I didn't pick that up in your post. But a couple options I can think of for unit tests

1. Simply create a stub, implementing only the methods you use.

2. Use a Mocking framework like Mockito, and mock the UriInfo. Example

   @Path("test")
   public class TestResource { 
       public String doSomthing(@Context UriInfo uriInfo){
           return uriInfo.getAbsolutePath().toString();
       }
   }
   [...]
   @Test
   public void doTest() {
       UriInfo uriInfo = Mockito.mock(UriInfo.class);
       Mockito.when(uriInfo.getAbsolutePath())
           .thenReturn(URI.create("http://localhost:8080/test"));
       TestResource resource = new TestResource();
       String response = resource.doSomthing(uriInfo);
       Assert.assertEquals("http://localhost:8080/test", response);
   }
   

   You'll need to add this dependency

   <dependency>
       <groupId>org.mockito</groupId>
       <artifactId>mockito-all</artifactId>
       <version>1.9.0</version>
   </dependency>
   

If you want to do an integration test, where the actual UriInfo is injected, you should look into Jersey Test Framework

Here's a complete example with the Jersey Test Framework

public class ResourceTest extends JerseyTest {

    @Path("test")
    public static class TestResource {
        @GET
        public Response doSomthing(@Context UriInfo uriInfo) {
            return Response.ok(uriInfo.getAbsolutePath().toString()).build();
        }
    }

    @Override
    public Application configure() {
        return new ResourceConfig(TestResource.class);
    }

    @Test
    public void test() {
        String response = target("test").request().get(String.class);
        Assert.assertTrue(response.contains("test"));
    }
}

Just add this dependency

<dependency>
    <groupId>org.glassfish.jersey.test-framework.providers</groupId>
    <artifactId>jersey-test-framework-provider-inmemory</artifactId>
    <version>${jersey2.version}</version>
</dependency>

It uses an in-memory container, which is the most efficient for small tests. There are other containers with Servlet support if needed. Just see the link I posted above.

One way is to use a Captor

ArgumentCaptor<List> captor = ArgumentCaptor.forClass(List.class);
verify(mock).createButtons(captor.capture());
assertEquals(x, captor.getValue().size()); // if expecting single list
assertEquals(x, captor.getValues().size()); // if expecting multiple lists

See #15 for the documentation.

You could also use a custom argument matcher. The documentation shows an example that does exactly what you want:

 class IsListOfTwoElements extends ArgumentMatcher<List> {
     public boolean matches(Object list) {
         return ((List) list).size() == 2;
     }
 }
 
 List mock = mock(List.class);
 when(mock.addAll(argThat(new IsListOfTwoElements()))).thenReturn(true);
 mock.addAll(Arrays.asList("one", "two"));
 verify(mock).addAll(argThat(new IsListOfTwoElements()));

You could, for instance, also add a constructor so you can specify list size desired, etc.

@InjectMocks
private CardRepositoryImpl cardRepositoryImpl;

when(cardRepositoryImpl.getCardOperation("2", Mockito.anyString()))
    .thenReturn(operationBean);

cardRepositoryImpl is not a mock, so you can't stub it. With @InjectMocks you are instructing Mockito to construct a real CardRepositoryImpl and have its private fields and constructor parameters substituted with fields on the test case. You'll probably want to use a spy instead; more on that in a second.

But first, why that error message? Because it's not a mock, the call to cardRepositoryImpl.getCardOperation happens on an actual CardRepositoryImpl instance. Mockito sees the interactions with operationBean (which does seem to be a mock), treats the when and thenReturn as corresponding with that most recent mock call, and erroneously tells you you're stubbing a void method (importantly, the wrong method) with a return value.

In a test for CardRepositoryImpl, you shouldn't be mocking CardRepositoryImpl, nor stubbing it to return values: This won't test anything, except that Mockito works. You should probably rethink what you need to stub in order for your test to work.

However, when stubbing one method, you might want to stub another method in the same class. This can be accomplished with a spy:

@Test
public void canGetCardOperation(){
    CardRepositoryImpl spyImpl = spy(cardRepositoryImpl);
    when(spyImpl.getCardOperation(Mockito.eq("2"), Mockito.anyString()))
        .thenReturn(returnValue);
    // ...
    spyImpl.someOtherMethod();  // Any matching calls to getCardOperation from
                                // someOtherMethod will use the stub above.
}

Side note: You use anyString and "2" adjacently while stubbing. When using Matchers like anyString, you need to use them for all arguments if you use them for any arguments at all. See more here.