How to use compareToNonCompareable method of org.mockito.internal.invocation.TypeSafeMatchingTest class

User Matcher documentation isA() method.

public static <T> T isA(java.lang.Class<T> clazz)

That will solve your problem.

verify(foo).putObject(isA(SomeClass.class));

Here is my solution to your problem:

import static org.mockito.Mockito.mockingDetails;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MockitoSkipAutowireConfiguration {

@Bean MockBeanFactory mockBeanFactory() {
    return new MockBeanFactory();
}

private static class MockBeanFactory extends InstantiationAwareBeanPostProcessorAdapter {
    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        return !mockingDetails(bean).isMock();
    }
}

} 

and then just

@Import(MockitoSkipAutowireConfiguration.class)

in your test @Configuration and you are all set

I solved in this way:

@Spy Response response;

...

// for assignments in code under testing:
doReturn( response ).when( dwConnector ).getResource( anyString() );

// for entity and response status reading:
doReturn( "{a:1}".getBytes() ).when( response ).readEntity( byte[].class );
doReturn( 200 ).when( response ).getStatus();

OK, this is a bad thing to be doing. Don't mock a list; instead, mock the individual objects inside the list. See Mockito: mocking an arraylist that will be looped in a for loop for how to do this.

Also, why are you using PowerMock? You don't seem to be doing anything that requires PowerMock.

But the real cause of your problem is that you are using when on two different objects, before you complete the stubbing. When you call when, and provide the method call that you are trying to stub, then the very next thing you do in either Mockito OR PowerMock is to specify what happens when that method is called - that is, to do the thenReturn part. Each call to when must be followed by one and only one call to thenReturn, before you do any more calls to when. You made two calls to when without calling thenReturn - that's your error.

For the mocks initialization, using the runner or the MockitoAnnotations.initMocks are strictly equivalent solutions. From the javadoc of the MockitoJUnitRunner :

JUnit 4.5 runner initializes mocks annotated with Mock, so that explicit usage of MockitoAnnotations.initMocks(Object) is not necessary. Mocks are initialized before each test method.

The first solution (with the MockitoAnnotations.initMocks) could be used when you have already configured a specific runner (SpringJUnit4ClassRunner for example) on your test case.

The second solution (with the MockitoJUnitRunner) is the more classic and my favorite. The code is simpler. Using a runner provides the great advantage of automatic validation of framework usage (described by @David Wallace in this answer).

Both solutions allows to share the mocks (and spies) between the test methods. Coupled with the @InjectMocks, they allow to write unit tests very quickly. The boilerplate mocking code is reduced, the tests are easier to read. For example:

@RunWith(MockitoJUnitRunner.class)
public class ArticleManagerTest {

    @Mock private ArticleCalculator calculator;
    @Mock(name = "database") private ArticleDatabase dbMock;
    @Spy private UserProvider userProvider = new ConsumerUserProvider();

    @InjectMocks private ArticleManager manager;

    @Test public void shouldDoSomething() {
        manager.initiateArticle();
        verify(database).addListener(any(ArticleListener.class));
    }

    @Test public void shouldDoSomethingElse() {
        manager.finishArticle();
        verify(database).removeListener(any(ArticleListener.class));
    }
}

Pros: The code is minimal

Cons: Black magic. IMO it is mainly due to the @InjectMocks annotation. With this annotation "you loose the pain of code" (see the great comments of @Brice)

The third solution is to create your mock on each test method. It allow as explained by @mlk in its answer to have "self contained test".

public class ArticleManagerTest {

    @Test public void shouldDoSomething() {
        // given
        ArticleCalculator calculator = mock(ArticleCalculator.class);
        ArticleDatabase database = mock(ArticleDatabase.class);
        UserProvider userProvider = spy(new ConsumerUserProvider());
        ArticleManager manager = new ArticleManager(calculator, 
                                                    userProvider, 
                                                    database);

        // when 
        manager.initiateArticle();

        // then 
        verify(database).addListener(any(ArticleListener.class));
    }

    @Test public void shouldDoSomethingElse() {
        // given
        ArticleCalculator calculator = mock(ArticleCalculator.class);
        ArticleDatabase database = mock(ArticleDatabase.class);
        UserProvider userProvider = spy(new ConsumerUserProvider());
        ArticleManager manager = new ArticleManager(calculator, 
                                                    userProvider, 
                                                    database);

        // when 
        manager.finishArticle();

        // then
        verify(database).removeListener(any(ArticleListener.class));
    }
}

Pros: You clearly demonstrate how your api works (BDD...)

Cons: there is more boilerplate code. (The mocks creation)

My recommandation is a compromise. Use the @Mock annotation with the @RunWith(MockitoJUnitRunner.class), but do not use the @InjectMocks :

@RunWith(MockitoJUnitRunner.class)
public class ArticleManagerTest {

    @Mock private ArticleCalculator calculator;
    @Mock private ArticleDatabase database;
    @Spy private UserProvider userProvider = new ConsumerUserProvider();

    @Test public void shouldDoSomething() {
        // given
        ArticleManager manager = new ArticleManager(calculator, 
                                                    userProvider, 
                                                    database);

        // when 
        manager.initiateArticle();

        // then 
        verify(database).addListener(any(ArticleListener.class));
    }

    @Test public void shouldDoSomethingElse() {
        // given
        ArticleManager manager = new ArticleManager(calculator, 
                                                    userProvider, 
                                                    database);

        // when 
        manager.finishArticle();

        // then 
        verify(database).removeListener(any(ArticleListener.class));
    }
}

Pros: You clearly demonstrate how your api works (How my ArticleManager is instantiated). No boilerplate code.

Cons: The test is not self contained, less pain of code

As a starting point and demonstration for the principal you can start with the following snippet.

// define the headers you want to be returned
Map<String, String> headers = new HashMap<>();
headers.put(null, "HTTP/1.1 200 OK");
headers.put("Content-Type", "text/html");

// create an Enumeration over the header keys
Enumeration<String> headerNames = Collections.enumeration(headers.keySet());

// mock HttpServletRequest
HttpServletRequest request = mock(HttpServletRequest.class);
// mock the returned value of request.getHeaderNames()
when(request.getHeaderNames()).thenReturn(headerNames);

System.out.println("demonstrate output of request.getHeaderNames()");
while (headerNames.hasMoreElements()) {
    System.out.println("header name: " + headerNames.nextElement());
}
    
// mock the returned value of request.getHeader(String name)
doAnswer(new Answer<String>() {
    @Override
    public String answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        return headers.get((String) args[0]);
    }
}).when(request).getHeader("Content-Type");

System.out.println("demonstrate output of request.getHeader(String name)");
String headerName = "Content-Type";
System.out.printf("header name: [%s]   value: [%s]%n", 
        headerName, request.getHeader(headerName));
}

Output

demonstrate output of request.getHeaderNames()
header name: null
header name: Content-Type

demonstrate output of request.getHeader(String name)
header name: [Content-Type]   value: [text/html]

The rule S2699 (Tests should include assertions) from the SonarQube Java Analyzer does not perform cross-procedural analysis and only explore body of methods being identified as test method (usually annotated with @Test).

Consequently, if the only assertions which will be called when executing the test method are done by a dedicated method (to avoid duplication), then the rule will raise an issue. This is a known limitation of the rule and we will deal with it only when we will be able to efficiently perform cross-procedural analysis.

Regarding the issues raised by SonarQube on such cases, you can safely mark them as Won't Fix.

Regarding the detected assertions, the rule consider as assertions the usual assert/fail/verify/expect methods from the following (unit test) frameworks :

• JUnit
• Fest (1.x & 2.x)
• AssertJ
• Hamcrest
• Mockito
• Spring
• EasyMock

You can use the Mockito shipped answers:

when(mock.something()).then(AdditionalAnswers.returnsFirstArg())

Where AdditionalAnswers.returnsFirstArg() could be statically imported.

As a starting point and demonstration for the principal you can start with the following snippet.

// define the headers you want to be returned
Map<String, String> headers = new HashMap<>();
headers.put(null, "HTTP/1.1 200 OK");
headers.put("Content-Type", "text/html");

// create an Enumeration over the header keys
Enumeration<String> headerNames = Collections.enumeration(headers.keySet());

// mock HttpServletRequest
HttpServletRequest request = mock(HttpServletRequest.class);
// mock the returned value of request.getHeaderNames()
when(request.getHeaderNames()).thenReturn(headerNames);

System.out.println("demonstrate output of request.getHeaderNames()");
while (headerNames.hasMoreElements()) {
    System.out.println("header name: " + headerNames.nextElement());
}
    
// mock the returned value of request.getHeader(String name)
doAnswer(new Answer<String>() {
    @Override
    public String answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        return headers.get((String) args[0]);
    }
}).when(request).getHeader("Content-Type");

System.out.println("demonstrate output of request.getHeader(String name)");
String headerName = "Content-Type";
System.out.printf("header name: [%s]   value: [%s]%n", 
        headerName, request.getHeader(headerName));
}

Output

demonstrate output of request.getHeaderNames()
header name: null
header name: Content-Type

demonstrate output of request.getHeader(String name)
header name: [Content-Type]   value: [text/html]