How to use no_interactions method of org.mockitousage.internal.junit.UnusedStubbingsFinderTest class

MockitoJUnitRunner gives you automatic validation of framework usage, as well as an automatic initMocks().

The automatic validation of framework usage is actually worth having. It gives you better reporting if you make one of these mistakes.

• You call the static when method, but don't complete the stubbing with a matching thenReturn, thenThrow or then. (Error 1 in the code below)

• You call verify on a mock, but forget to provide the method call that you are trying to verify. (Error 2 in the code below)

• You call the when method after doReturn, doThrow or doAnswer and pass a mock, but forget to provide the method that you are trying to stub. (Error 3 in the code below)

If you don't have validation of framework usage, these mistakes are not reported until the following call to a Mockito method. This might be

• in the same test method (like error 1 below),
• in the next test method (like error 2 below),
• in the next test class.

If they occur in the last test that you run (like error 3 below), they won't be reported at all.

Here's how each of those types of errors might look. Assume here that JUnit runs these tests in the order they're listed here.

@Test
public void test1() {

    // ERROR 1
    // This compiles and runs, but it's an invalid use of the framework because 
    // Mockito is still waiting to find out what it should do when myMethod is called.
    // But Mockito can't report it yet, because the call to thenReturn might 
    // be yet to happen.
    when(myMock.method1());

    doSomeTestingStuff();

    // ERROR 1 is reported on the following line, even though it's not the line with
    // the error.
    verify(myMock).method2();

}

@Test
public void test2() {

    doSomeTestingStuff();

    // ERROR 2
    // This compiles and runs, but it's an invalid use of the framework because
    // Mockito doesn't know what method call to verify.  But Mockito can't report 
    // it yet, because the call to the method that's being verified might 
    // be yet to happen.
    verify(myMock);
}

@Test
public void test3() {

    // ERROR 2 is reported on the following line, even though it's not even in 
    // the same test as the error.
    doReturn("Hello").when(myMock).method1();


    // ERROR 3
    // This compiles and runs, but it's an invalid use of the framework because
    // Mockito doesn't know what method call is being stubbed.  But Mockito can't 
    // report it yet, because the call to the method that's being stubbed might 
    // be yet to happen.

    doReturn("World").when(myMock);

    doSomeTestingStuff(); 

    //  ERROR 3 is never reported, because there are no more Mockito calls. 
}

Now when I first wrote this answer more than five years ago, I wrote

So I would recommend the use of the MockitoJUnitRunner wherever possible. However, as Tomasz Nurkiewicz has correctly pointed out, you can't use it if you need another JUnit runner, such as the Spring one.

My recommendation has now changed. The Mockito team have added a new feature since I first wrote this answer. It's a JUnit rule, which performs exactly the same function as the MockitoJUnitRunner. But it's better, because it doesn't preclude the use of other runners.

Include

@Rule 
public MockitoRule rule = MockitoJUnit.rule();

in your test class. This initialises the mocks, and automates the framework validation; just like MockitoJUnitRunner does. But now, you can use SpringJUnit4ClassRunner or any other JUnitRunner as well. From Mockito 2.1.0 onwards, there are additional options that control exactly what kind of problems get reported.

This is what you want:

@RunWith(MockitoJUnitRunner.class)
public class MyAppTest { 

    @Mock private OpportunitiesService mocked_m_oppsSvc;
    @InjectMocks MyApp myApp;

    @Test public void when_MyApp_uses_OpportunititesService_then_verify_something() { 
        // given
        given( mocked_m_oppsSvc.whatever()).willReturn(...);

        // when
        myApp.isUsingTheOpportunitiesService(...);

        // then
        verify...
        assertThat...
    }
}

Using: Mockito 1.9.0, BDD style, FEST-Assert AssertJ.

Hope that helps :)

I found a way to use PowerMock in conjunction with Robolectric.

In addition to the standard PowerMock jars, the PowerMock Junit Rule is also needed. It is described here how to grab it. I used the xstream classloading version, because the objenesis one is very buggy. This is working with PowerMock 1.5.5 and Robolectric 2.3, i cannot speak about the older versions. Also please note that the Java agent should not be included, because from my experience it causes problems.

So if you are using maven, these dependencies should be declared:

<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4</artifactId>
    <version>${powermock.version}</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4-rule</artifactId>
    <version>${powermock.version}</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-api-mockito</artifactId>
    <version>${powermock.version}</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-classloading-xstream</artifactId>
    <version>${powermock.version}</version>
    <scope>test</scope>
</dependency>

Then you have to setup your test class like this:

@RunWith(RobolectricTestRunner.class)
@PowerMockIgnore({ "org.mockito.*", "org.robolectric.*", "android.*" })
@PrepareForTest(Static.class)
public class MyTest {

    @Rule
    public PowerMockRule rule = new PowerMockRule();

    private MyActivity activity;

    @Before
    public void setup() {
        activity = Robolectric.buildActivity(MyActivity.class).create().get();
    }

    @Test
    public void test() throws Exception {
        PowerMockito.mockStatic(Static.class);
        Mockito.when(Static.getCurrentTime()).thenReturn(1);

        Assert.assertEquals(1, activity.getId());
    }
}

You need to create a MOCK of pcUserService first, and then use that mock.

PcUserService mock = org.mockito.Mockito.mock(PcUserService.class);
when(mock.read("1")).thenReturn(pcUser);

Mockito 1.8.1 introduced anyVararg() matcher:

when(a.b(anyInt(), anyInt(), Matchers.<String>anyVararg())).thenReturn(b);

Also see history for this: https://code.google.com/archive/p/mockito/issues/62

Edit new syntax after deprecation:

when(a.b(anyInt(), anyInt(), ArgumentMatchers.<String>any())).thenReturn(b);

In new Mockito versions you can use stubbing consecutive calls to throw exception on first can and returning a value on a second call.

when(mock.someMethod("some arg"))
    .thenThrow(new RuntimeException())
    .thenReturn("foo");

https://javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/Mockito.html#10

You can not force a subclass to override a method. You can only force it to implement a method by making it abstract.

So if you can not make myMotherClass abstract you can only introduce another superclass that extends myMotherClass and delegates to the method that must be implemented:

public abstract class EnforceImplementation extends myMotherClass {

        public final void myMethod(){
             implementMyMethod();
        }

        public abstract void implementMyMethod();
}

EDIT

I found another interessting way of solving the problem in the hemcrest api that is e.g. used by mockito.

public interface Matcher<T> extends SelfDescribing {

    /**
     * Evaluates the matcher for argument <var>item</var>.
     * <p/>
     * This method matches against Object, instead of the generic type T. This is
     * because the caller of the Matcher does not know at runtime what the type is
     * (because of type erasure with Java generics). It is down to the implementations
     * to check the correct type. 
     *
     * @param item the object against which the matcher is evaluated.
     * @return <code>true</code> if <var>item</var> matches, otherwise <code>false</code>.
     *
     * @see BaseMatcher
     */
    boolean matches(Object item);

    /**
     * This method simply acts a friendly reminder not to implement Matcher directly and
     * instead extend BaseMatcher. It's easy to ignore JavaDoc, but a bit harder to ignore
     * compile errors .
     *
     * @see Matcher for reasons why.
     * @see BaseMatcher
     */
    void _dont_implement_Matcher___instead_extend_BaseMatcher_();
}

The interface specifies a method _dont_implement_Matcher___instead_extend_BaseMatcher_. Of course it does not prevent others from implementing the Matcher interface, but it guides the developer in the right direction.

And the BaseMatcher class implements the _dont_implement_Matcher___instead_extend_BaseMatcher_ method as final

public final void _dont_implement_Matcher___instead_extend_BaseMatcher_() {
    // See Matcher interface for an explanation of this method.
}

Finally I think that this is a design problem, because the BaseMatcher obviouosly implements logic that every Matcher should implement. Thus it would have been better to make the Matcher an abstract class and use a template method.

But I guess they did it because it was the best compromise between bytecode compatibility and new features.

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.

The message is pretty obvious: You can't mock non-visible and final classes. Short answer : Create a named class of your anonymous one, and test this class instead!

Long answer, let's dig why !

An anonymous class is final

You instantiate an anonymous class of FilterFactory, when the compiler sees an anonymous class, it creates a final and package visible class. So the anonymous class is not mockable through standard mean i.e. through Mockito.

Mocking anonymous class : possible but BRITTLE if not HACKY

OK, now suppose you want to be able to mock this anonymous class through Powermock. Current compilers compile anonymous class with following scheme :

Declaring class + $ + <order of declaration starting with 1>

Mocking anonymous class possible but brittle (And I mean it) So supposing the anonymous class is the eleventh to be declared, it will appear as

InputHelper$11.class

So you could potentially prepare for test the anonymous class:

@RunWith(PowerMockRunner.class)
@PrepareForTest({InputHelper$11.class})
public class InputHelperTest {
    @Test
    public void anonymous_class_mocking works() throws Throwable {
        PowerMockito.spy(InputHelper.BZIP2_FACTORY);  // This line fails
    }
}

This code will compile, BUT will eventually be reported as an error with your IDE. The IDE probably doesn't know about InputHelper$11.class. IntelliJ who doesn't use compiled class to check the code report so.

Also the fact that the anonymous class naming actually depends on the order of the declaration is a problem, when someone adds another anonymous class before, the numbering could change. Anonymous classes are made to stay anonymous, what if the compiler guys decide one day to use letters or even random identifiers!

So mocking anonymous classes through Powermock is possible but brittle, don't ever do that in a real project!

EDITED NOTE : The Eclipse compiler has a different numbering scheme, it always uses a 3 digit number :

Declaring class + $ + <pad with 0> + <order of declaration starting with 1>

Also I don't think the JLS clearly specify how the compilers should name anonymous classes.

You don't reassign the spy to the static field

PowerMockito.spy(InputHelper.BZIP2_FACTORY);  // This line fails
whenNew(BufferedInputStream.class).withArguments(in).thenReturn(buffer);
whenNew(CBZip2InputStream.class).withArguments(buffer).thenReturn(expected);
InputStream observed = InputHelper.BZIP2_FACTORY.makeFilter(in);

PowerMockito.spy returns the spy, it doesn't change the value of InputHelper.BZIP2_FACTORY. So you would need to actually set via reflection this field. You can use the Whiteboxutility that Powermock provide.

Conclusion

Too much trouble to just test with mocks that the anonymous filter uses a BufferedInputStream.

Alternative

I would rather write the following code:

An input helper that will use the named class, I don't use the interface name to make clear to the user what is the intent of this filter!

public class InputHelper {
    public static final BufferedBZIP2FilterFactory BZIP2_FACTORY = new BufferedBZIP2FilterFactory();
}

And now the filter itself :

public class BufferedBZIP2FilterFactory {
    public InputStream makeFilter(InputStream in) {
        BufferedInputStream buffer = new BufferedInputStream(in);
        return new CBZip2InputStream(buffer);
    }
}

Now you can write a test like this :

@RunWith(PowerMockRunner.class)
public class BufferedBZIP2FilterFactoryTest {

    @Test
    @PrepareForTest({BufferedBZIP2FilterFactory.class})
    public void wraps_InputStream_in_BufferedInputStream() throws Exception {
        whenNew(CBZip2InputStream.class).withArguments(isA(BufferedInputStream.class))
                .thenReturn(Mockito.mock(CBZip2InputStream.class));

        new BufferedBZIP2FilterFactory().makeFilter(anInputStream());

        verifyNew(CBZip2InputStream.class).withArguments(isA(BufferedInputStream.class));
    }

    private ByteArrayInputStream anInputStream() {
        return new ByteArrayInputStream(new byte[10]);
    }
}

But could eventually avoid powermock stuff for this test scenario if you force the CBZip2InputStream to only accept BufferedInputStream. Usually using Powermock means something is wrong with the design. In my opinion Powermock is great for legacy softwares, but can blind developers when designing new code; as they are missing the point of OOP's good part, I would even say they are designing legacy code.

Hope that helps !