How to use getStackTraceCleaner method of org.mockitousage.plugins.stacktrace.MyStackTraceCleanerProvider class

First Mock your Worker with Mockito (just as you did). Also mock your ChildService. Then:

@Test
public void shouldUseChildService() {
  ArgumentCaptor<Callable> callableCaptor = ArgumentCaptor.forClass(Callable.class);
  ArgumentCaptor<Consumer> consumerCaptor = ArgumentCaptor.forClass(Consumer.class);

  parentService.doAction();

  verify(worker).execute(callableCaptor.capture(), consumerCaptor.capture());
  callableCaptor.getValue().call(); //this will execute whatever was captured
  consumerCaptor.getValue().accept(null);//this will execute whatever was captured

  // now verify that childService::listClients and childService::refreshObjects have been called
}

A Mock object is something used for unit testing. If you have an object whose methods you want to test, and those methods depend on some other object, you create a mock of the dependency rather than an actual instance of that dependency. This allows you to test your object in isolation.

Common Java frameworks for creating mock objects include JMock and EasyMock. They generally allow you to create mock objects whose behavior you can define, so you know exactly what to expect (as far as return values and side effects) when you call methods on the mock object.

As an example, one common use case might be in an MVC application, where you have a DAO layer (data access objects) and a Controller that performs business logic. If you'd like to unit test the controller, and the controller has a dependency on a DAO, you can make a mock of the DAO that will return dummy objects to your controller.

One thing thats important to note is that its usually the case that mock objects implement the same interface as the objects that they are mocking - this allows your code to deal with them via the interface type, as if they are instances of the real thing.

First, create a ResponseEntity object:

HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON);

ResponseEntity<?> responseEntity = new ResponseEntity<>(
    "some response body",
    header, 
    HttpStatus.OK
);

Then build a mock to return the responseEntity object:

when(restC.SomeMethod(client)).thenReturn(responseEntity);

Point to pay attention:

Avoid to use ResponseEntity inside @Service class. You should use ResponseEntity in @RestController class.

And you can Inject your @Service class using @Autowired annotation, like:

@RestController
public class YourControllerClass {

    @Autowired
    private YourServiceClass yourServiceClass;

Or using constructor, like:

@RestController
public class YourControllerClass {

    private YourServiceClass yourServiceClass;

    public YourControllerClass(YourServiceClass yourServiceClass) {
        this.yourServiceClass= yourServiceClass;
    }

So:

@Service class will handle business or data objects and @RestController class will handle Response and Request objects. Thus we have Single Responsibility principle.

Some nice links:

• Spring MVC - Using RequestEntity and ResponseEntity
• How do I mock a REST template
• Building REST services with Spring
• Understanding the Single Responsibility Principle

Hope this helps!

The problem with using RETURN_DEEP_STUBS is that you'll get a different mock each time you call a method. I think from your question that you want to use a default Answer that actually returns the mock on which it was called, for each method that has the right return type. This could look something like the following. Note that I haven't tested this, so it may contain typos, but I hope that the intention is clear in any case.

import static org.mockito.Mockito.RETURNS_DEFAULTS;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;

public class SelfReturningAnswer implements Answer<Object> {

    public Object answer(InvocationOnMock invocation) throws Throwable {
        Object mock = invocation.getMock();
        if(invocation.getMethod().getReturnType().isInstance(mock)){
            return mock;
        }
        return RETURNS_DEFAULTS.answer(invocation);
    }
}

Then, when you create your mock, specify this as your default answer. This will make your mock return itself from each method that it can; but it will behave like an ordinary mock when you call a method whose return type is wrong for the mock.

Create your mock like this

Builder mockBuilder = mock( Builder.class, new SelfReturningAnswer());

or create a constant for this class and write something like

@Mock(answer = SELF_RETURNING) private Builder mockBuilder;

Hope that helps.

Don't mock the InputStream. Instead, transform the String to an array of bytes using the getBytes() method. Then create a ByteArrayInputStream with the array as input, so that it returns the String when consumed, each byte at a time. Next, create a ServletInputStream that wraps a regular InputStream like the one from Spring:

public class DelegatingServletInputStream extends ServletInputStream {

    private final InputStream sourceStream;


    /**
     * Create a DelegatingServletInputStream for the given source stream.
     * @param sourceStream the source stream (never <code>null</code>)
     */
    public DelegatingServletInputStream(InputStream sourceStream) {
        Assert.notNull(sourceStream, "Source InputStream must not be null");
        this.sourceStream = sourceStream;
    }

    /**
     * Return the underlying source stream (never <code>null</code>).
     */
    public final InputStream getSourceStream() {
        return this.sourceStream;
    }


    public int read() throws IOException {
        return this.sourceStream.read();
    }

    public void close() throws IOException {
        super.close();
        this.sourceStream.close();
    }

}

and finally, the HttpServletRequest mock would return this DelegatingServletInputStream object.

There's no API for that at that time. You can try to code your own verifier code using MockingDetails.getInvocations

Mockito.mockingDetails(mock).getInvocations()

You haven't mocked the behavior of getId in externalDependencyObject therefore it is returning null and giving you the NPE when toString() is called on that null.

You need a when(externalDependencyObject.getId()).then...

Use ResourceBundle.getBundle( String, ResourceBundle.Control ) to get ResourceBundle to cache a bundle for the given String. You can subclass ResourceBundle.Control to provide any type of bundle your heart desires.

@Test
public void myTest()
{
    // In your Test's init phase run an initial "getBundle()" call
    // with your control.  This will cause ResourceBundle to cache the result.
    ResourceBundle rb1 = ResourceBundle.getBundle( "blah", myControl );

    // And now calls without the supplied Control will still return
    // your mocked bundle.  Yay!
    ResourceBundle rb2 = ResourceBundle.getBundle( "blah" );
}

Here's the subclassed Control:

ResourceBundle.Control myControl = new ResourceBundle.Control()
{
    public ResourceBundle newBundle( String baseName, Locale locale, String format,
            ClassLoader loader, boolean reload )
    {
        return myBundle;
    }
};

And here's one way to mock the ResourceBundle (filling up the TreeMap with keys/values as needed for the unit tests left as an exercise for the reader):

ResourceBundle myBundle = new ResourceBundle()
{
    protected void setParent( ResourceBundle parent )
    {
      // overwritten to do nothing, otherwise ResourceBundle.getBundle(String)
      //  gets into an infinite loop!
    }

    TreeMap<String, String> tm = new TreeMap<String, String>();

    @Override
    protected Object handleGetObject( String key )
    {
        return tm.get( key );
    }

    @Override
    public Enumeration<String> getKeys()
    {
        return Collections.enumeration( tm.keySet() );
    }
};

When you say

@Mock
Fruit fruit;

You tell Mockito: the fruit variable should be an instance of Fruit. Mockito will dynamically create a class which implements Fruit (this class is Fruit$$EnhancerByMockitoWithCGLIB$$b8254f54), and create an instance of this class. There's no reason for this class to be an instance of AppleFruit, since you didn't tell Mockito that the object had to be of type AppleFruit.

Declare it as AppleFruit, and it will be of type AppleFruit.