How to use InlineDelegateByteBuddyMockMakerTest class of org.mockito.internal.creation.bytebuddy package

Mockito 1.10.5 has introduced this feature.

For the code sample in the question, here is one way to capture the varargs:

    ArgumentCaptor<String> varArgs = ArgumentCaptor.forClass(String.class);
    A mock = Mockito.mock(A.class);
    mock.setNames("Jeff", "Mike", "John");
    Mockito.verify(mock).setNames(varArgs.capture());

    //Results may be validated thus:
    List<String> expected = Arrays.asList("Jeff", "Mike", "John");
    assertEquals(expected, varArgs.getAllValues());

Please see the ArgumentCaptor javadoc for details.

The nested generics-problem can be avoided with the @Captor annotation:

public class Test{

    @Mock
    private Service service;

    @Captor
    private ArgumentCaptor<ArrayList<SomeType>> captor;

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

    @Test 
    public void shouldDoStuffWithListValues() {
        //...
        verify(service).doStuff(captor.capture()));
    }
}

Some tools to support some practices:

• xUnit tools family for testing
• EasyMock + PowerMock (alternatives: Mockito, JMock) for mocking
• Cobertura (alternatives: EMMA, Clover) for code coverage
• Checkstyle, FindBugs, PMD for static analysis
• Hudson (alternatives: TeamCity, Bamboo) for Continuous Integration
• Sonar as QA dashboard
• XWiki (alternative: Trac, Confluence) for documentation and Knowledge Management
• Review Board (alternatives: Crucible, SmartBear) for Code Review

But these are just tools, tools won't make you Agile by themselves.

Instead of mocking you can create a dummy ResourceBundle implementation, and then pass it as an argument to .thenReturn(resourceBundle):

    import java.util.ResourceBundle;

    ResourceBundle dummyResourceBundle = new ResourceBundle() {
        @Override
        protected Object handleGetObject(String key) {
            return "fake_translated_value";
        }

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

    // Example usage
    when(request.getResourceBundle(any(Locale.class))).thenReturn(dummyResourceBundle)

If you need the actual keys and values, then you'll need to provide an implementation for getKeys(), e.g. a hashmap for storage and key lookup.

You could use a Mockito Answer for this.

doAnswer(new Answer<Object>(){
     @Override
     public Object answer(InvocationOnMock invocation){
        Article article = (Article) invocation.getArguments()[0];
        article.setId(1L);
        return null;
     }
  }).when(em).persist(any(Article.class));

This tells Mockito that when the persist method is called, the first argument should have its setId method invoked.

But if you do this, I don't understand what the purpose of the test would be. You'd really just be testing that the Mockito Answer mechanism works, not that the code of Article or of EntityManager works correctly.

In Java 8 it is even simpler than all of the above:

when(mockObject.myMethod(anyString()))
    .thenAnswer(invocation -> 
        invocation.getArgumentAt(0, String.class));

If you are using Spring (the spring-test library specifically), you can simply use ReflectionTestUtils.setField instead of Whitebox.setInternalState

As noted in another answer, if you don't care about the order, you might do best to change the interface so it doesn't care about the order.

If order matters in the code but not in a specific test, you can use the ArgumentCaptor as you did. It clutters the code a bit.

If this is something you might do in multiple tests, you might do better to use appropriate Mockito Matchers or Hamcrest Matchers, or roll your own (if you don't find one that fills the need). A hamcrest matcher might be best as it can be used in other contexts besides mockito.

For this example you could create a hamcrest matcher as follows:

import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Matcher;

import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class MyMatchers {
    public  static <T> Matcher<List<T>> sameAsSet(final List<T> expectedList) {
        return new BaseMatcher<List<T>>(){
            @Override
            public boolean matches(Object o) {
                List<T> actualList = Collections.EMPTY_LIST;
                try {
                    actualList = (List<T>) o;
                }
                catch (ClassCastException e) {
                    return false;
                }
                Set<T> expectedSet = new HashSet<T>(expectedList);
                Set<T> actualSet = new HashSet<T>(actualList);
                return actualSet.equals(expectedSet);
            }

            @Override
            public void describeTo(Description description) {
                description.appendText("should contain all and only elements of ").appendValue(expectedList);
            }
        };
    }
}

And then the verify code becomes:

verify(mockClassB).sendEvent(argThat(MyMatchers.sameAsSet(expectedFileList)));

If you instead created a mockito matcher, you wouldn't need the argThat, which basically wraps a hamcrest matcher in a mockito matcher.

This moves the logic of sorting or converting to set out of your test and makes it reusable.

You can check for more properties using one matcher by combining matchers with allOf:

    Matcher<Class> matcherName = allOf(
        hasProperty("propertyName", equalTo(expected1)),
        hasProperty("propertyName2", equalTo(expected2)));

But I guess that what you are actually looking for is the samePropertyValuesAs one, that checks if a bean has the same property values as another one by checking the properties itself instead of the equals method:

    assertThat(yourBean, samePropertyValuesAs(expectedBean));