How to use doThrow method of org.mockito.internal.stubbing.StubberImpl class

Some of the other answers offer alternatives to doing exactly what I want here, but this is doable by Spying the Consumer class itself and having the spy call the method you really want to execute. A helper method for wrapping the lambda to create the spy helps here:

/** Get a spied version of the given Consumer. */
private Consumer<Item> itemHandlerSpy(Consumer<Item> itemHandler) {
  // Create a spy of the Consumer functional interface itself.
  @SuppressWarnings("unchecked")
  Consumer<Item> spy = (Consumer<Item>) Mockito.spy(Consumer.class);
  // Tell the spy to run the given consumer when the Consumer is given something to consume. 
  Mockito.doAnswer(it -> {
    // Get the first (and only) argument passed to the Consumer.
    Item item = (Item) it.getArguments()[0];
    // Pass it to the real consumer so it gets processed.
    itemHandler.accept(item);
    return null;
  }).when(spy).accept(Mockito.any(Item.class));
  return spy;
}

And then the test method becomes very straightforward:

Consumer<Item> itemHandler = itemHandlerSpy(Item::foo);
instance.conditionalRun(itemHandler);
// This verifies conditionalRun called the Consumer exactly once.
Mockito.verify(itemHandler).accept(Mockito.any(Item.class));

In the end, this is all about wording.

When you think of "correct" in its very fundamental sense, as in correctness, then the answer is simply: no.

You see, the goal of an integration test is to ensure that your integrated system (consisting of multiple, different components) functions as expected. The purpose of an integration test is to verify that your "plumbing" of components works as expected. Therefore: you can't verify that your system works when parts of that system are mocked out.

But then, you can think "correctness" less strictly.

Example: companies selling cars have to test ECUs. Basically a piece of hardware, running a potentially huge software stack. These ECUs normally operate within cars. So when you want to integration test an ECU, you would have to put the ECU into a car for testing, right? A car that probably doesn't exist yet. The solution here: there are hardware emulators. You plug the ECU into that emulator, and the ECU "thinks" that sits inside a real car.

So: there are good arguments to claim "a true integration test can't use mocking", but at the same time, in the real world, such "mocking" happens all the time.

The real answer is therefore: it depends on context. Therefore there isn't a universal answer. Instead, this is about communication. You "simply" have to ensure that all people in your group/org have the same understanding of such terms.

The term itself can be interpreted in different ways. You (jointly!) pick that definition that best fits your needs, to then make sure all people contributing to your project share that view (or at least know about it).

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

The following suggestion let's you test abstract classes without creating a "real" subclass - the Mock is the subclass.

use Mockito.mock(My.class, Mockito.CALLS_REAL_METHODS), then mock any abstract methods that are invoked.

Example:

public abstract class My {
  public Result methodUnderTest() { ... }
  protected abstract void methodIDontCareAbout();
}

public class MyTest {
    @Test
    public void shouldFailOnNullIdentifiers() {
        My my = Mockito.mock(My.class, Mockito.CALLS_REAL_METHODS);
        Assert.assertSomething(my.methodUnderTest());
    }
}

Note: The beauty of this solution is that you do not have to implement the abstract methods, as long as they are never invoked.

In my honest opinion, this is neater than using a spy, since a spy requires an instance, which means you have to create an instantiatable subclass of your abstract class.

Well, you have made quite some number of mistakes...

1. I'm sure you wanted to annotate private RetryTemplate retryTemplate; with @Mock, not @InjectMocks
2. @InjectMocks should go onto ServiceRequest serviceRequest;
3. You are defining interactions on some mockRetryTemplate and mockRestTemplate which have nothing to do with serviceRequest. Instead, you should use your @Mock-annotated fields to define interactions on because they are being injected into your object under test (serviceRequest)
4. Moreover, you can't normally mock RestTemplate and inject it into your ServiceRequest because you don't use dependency injection in the first place for RestTemplate in ServiceRequest. You just instantiate its instance in ServiceRequest.makeGetServiceCall
5. You are defining an interaction on the wrong method at line Mockito.when(retryTemplate.execute(.... Your interaction specifies RetryTemplate.execute(RetryCallback, RecoveryCallback, RetryState) whereas your ServiceRequest uses another method RetryTemplate.execute(RetryCallback)
6. You should also notice that RetryTemplate.execute is final and so you can't mock it without extra efforts as explained here. And generally, you should prefer interfaces over classes, e.g. RestOperations and RetryOperations over RestTemplate and RetryTemplate respectively, to be more flexible.

That said, below is the working test which solves your problem. But take note of removing RestTemplate restTemplate = new RestTemplate(); from ServiceRequest and making restTemplate a field so it's dependency-injected.

@RunWith(MockitoJUnitRunner.class)
public class ServiceRequestTest {
    @Mock
    private RestTemplate restTemplate;

    @Mock
    public RequestConfig requestConfig;

    @Mock
    private RetryTemplate retryTemplate;

    @InjectMocks
    ServiceRequest serviceRequest;

    @Test
    public void makeGetServiceCall() throws Exception {
        //given:
        String url = "http://localhost:8080";
        ResponseEntity<String> myEntity = new ResponseEntity<>(HttpStatus.ACCEPTED);
        when(retryTemplate.execute(any(RetryCallback.class))).thenAnswer(invocation -> {
            RetryCallback retry = invocation.getArgument(0);
            return retry.doWithRetry(/*here goes RetryContext but it's ignored in ServiceRequest*/null);
        });
        when(restTemplate.exchange(eq(url), eq(HttpMethod.GET), any(HttpEntity.class), eq(String.class)))
                .thenReturn(myEntity);

        //when:
        ResponseEntity<String> response = serviceRequest.makeGetServiceCall(url);

        //then:
        assertEquals(myEntity, response);
    }
}

It's a defect in Mockito with loading plugins when context class loader is different from which is used to load PowerMock and Mockito.

It could be fixed in Mockito 2, but as it mentioned in comments

Not sure we have the build infrastructure to backport the fix on 1.x

For Mockito 1, fix cannot be delivered, so I fixed in in PowerMock and fix will be include in next PowerMock release (PowerMock 1.6.5).

EDIT 2020-09-21: Since 3.4.0, Mockito supports mocking static methods, API is still incubating and is likely to change, in particular around stubbing and verification. It requires the mockito-inline artifact. And you don't need to prepare the test or use any specific runner. All you need to do is :

@Test
public void name() {
    try (MockedStatic<LoggerFactory> integerMock = mockStatic(LoggerFactory.class)) {
        final Logger logger = mock(Logger.class);
        integerMock.when(() -> LoggerFactory.getLogger(any(Class.class))).thenReturn(logger);
        new Controller().log();
        verify(logger).warn(any());
    }
}

The two inportant aspect in this code, is that you need to scope when the static mock applies, i.e. within this try block. And you need to call the stubbing and verification api from the MockedStatic object.

@Mick, try to prepare the owner of the static field too, eg :

@PrepareForTest({GoodbyeController.class, LoggerFactory.class})

EDIT1 : I just crafted a small example. First the controller :

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Controller {
    Logger logger = LoggerFactory.getLogger(Controller.class);

    public void log() { logger.warn("yup"); }
}

Then the test :

import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static org.mockito.Matchers.any;
import static org.mockito.Matchers.anyString;
import static org.mockito.Mockito.verify;
import static org.powermock.api.mockito.PowerMockito.mock;
import static org.powermock.api.mockito.PowerMockito.mockStatic;
import static org.powermock.api.mockito.PowerMockito.when;

@RunWith(PowerMockRunner.class)
@PrepareForTest({Controller.class, LoggerFactory.class})
public class ControllerTest {

    @Test
    public void name() throws Exception {
        mockStatic(LoggerFactory.class);
        Logger logger = mock(Logger.class);
        when(LoggerFactory.getLogger(any(Class.class))).thenReturn(logger);
        
        new Controller().log();
        
        verify(logger).warn(anyString());
    }
}

Note the imports ! Noteworthy libs in the classpath : Mockito, PowerMock, JUnit, logback-core, logback-clasic, slf4j

EDIT2 : As it seems to be a popular question, I'd like to point out that if these log messages are that important and require to be tested, i.e. they are feature / business part of the system then introducing a real dependency that make clear theses logs are features would be a so much better in the whole system design, instead of relying on static code of a standard and technical classes of a logger.

For this matter I would recommend to craft something like= a Reporter class with methods such as reportIncorrectUseOfYAndZForActionX or reportProgressStartedForActionX. This would have the benefit of making the feature visible for anyone reading the code. But it will also help to achieve tests, change the implementations details of this particular feature.

Hence you wouldn't need static mocking tools like PowerMock. In my opinion static code can be fine, but as soon as the test demands to verify or to mock static behavior it is necessary to refactor and introduce clear dependencies.

You could simply mock your ResultSet to provide a value for each field and check that the result contains what you expect.

For example with Mockito, your test would be something like this:

@RunWith(MockitoJUnitRunner.class)
public class SomeClassTest {

    @Mock
    private ResultSet resultSet;

    @Test
    public void testConvert() throws SQLException {
        // Define the behavior of the mock for each getString method's call
        Mockito.when(resultSet.getString("id")).thenReturn("myId");
        Mockito.when(resultSet.getString("sysname")).thenReturn("myHost");
        Mockito.when(resultSet.getString("zos")).thenReturn("myOS");
        Mockito.when(resultSet.getString("customer_name")).thenReturn("myCustomerName");

        // Launch the method against your mock
        SomeClass someClass = new SomeClass();
        CItem item = someClass.convert(resultSet);

        // Check the result
        Assert.assertNotNull(item);
        Assert.assertEquals("myId", item.getHinumber());
        Assert.assertEquals("myHost", item.getHostname());
        Assert.assertEquals("myOS", item.getOs());
        Assert.assertEquals("myCustomerName", item.getTenant());
    }
}

It sounds like you may want to be using the .expects(1) type methods that mock frameworks usually provide.

Using mockito, if you were testing a List and wanted to verify that clear was called 3 times and add was called at least once with these parameters you do the following:

List mock = mock(List.class);        
someCodeThatInteractsWithMock();                 

verify(mock, times(3)).clear();
verify(mock, atLeastOnce()).add(anyObject());      

Source - MockitoVsEasyMock