How to use ClassPathLoaderTest class of org.mockito.internal.configuration package

The need is simple: to verify that the correct number of invocations were made. There are scenarios in which method calls should not happen, and others in which they should happen more or less than the default.

Consider the following modified version of embarkOnQuest:

public void embarkOnQuest() {
    quest.embark(); 
    quest.embarkAgain(); 
}

And suppose you are testing error cases for quest.embark():

@Test 
public void knightShouldEmbarkOnQuest() { 
    Quest mockQuest = mock(Quest.class); 
    Mockito.doThrow(RuntimeException.class).when(mockQuest).embark();
    ...
}

In this case you want to make sure that quest.embarkAgain is NOT invoked (or is invoked 0 times):

verify(mockQuest, times(0)).embarkAgain(); //or verifyZeroInteractions

Of course this is one other simple example. There are many other examples that could be added:

• A database connector that should cache entries on first fetch, one can make multiple calls and verify that the connection to the database was called just once (per test query)
• A singleton object that does initialization on load (or lazily), one can test that initialization-related calls are made just once.

Caused by: java.util.MissingResourceException: Can't find bundle for base name javax.servlet.LocalStrings, locale es_ES

That's the real error.

Your running tests are missing the servlet-api dependency.

If you're using maven make sure this dependency is in your project:

<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.1.0</version>
</dependency>

Unfortunately I can't tell you why this happened, but I can tell you how to get around this issue.

The problem was, that PowerMockito scanned tha class path and also added the RESTeasy classes (which are located within the package 'javax.ws.*'. Therefor the above mentioned RuntimeDelegate was loaded by the PowerMockito classloader and caused later the issue, that the class was compared against one from a different classloader.

To get around this issue, tell PowerMockito to ignore the javax.ws package when scanning for classes:

@PowerMockIgnore({"javax.ws.*"})

You can mock the template but it's better to mock the interface.

    Sender sender = new Sender();
    KafkaOperations template = mock(KafkaOperations.class);
    SettableListenableFuture<SendResult<String, String>> future = new SettableListenableFuture<>();
    when(template.send(anyString(), any(Message.class))).thenReturn(future);
    sender.setTemplate(template);
    sender.send(...);

    future.set(new SendResult<>(...));

    ...or...

    future.setException(...

You can use

  Mockito.doAnswer(new Answer<Void>() {
        @Override
        public Void answer(InvocationOnMock invocation) throws Throwable {
            //DO SOMETHING
            return null;
        }
    }).when(...).remove(Matchers.<String>anyVararg());

From the Javadoc:

Use doAnswer() when you want to stub a void method with generic Answer.

Stubbing voids requires different approach from Mockito.when(Object) because the compiler does not like void methods inside brackets...

Example:

    doAnswer(new Answer() {
    public Object answer(InvocationOnMock invocation) {
        Object[] args = invocation.getArguments();
        Mock mock = invocation.getMock();
        return null;
    }}).when(mock).someMethod();

See examples in javadoc for Mockito

Why it didn't work

You're mocking Result.iterator():

when(deviceDataResultMock.iterator()).thenReturn(resultIterator);

But you didn't mock Result.spliterator(), or at least I didn't see it, which is what's being called by Result.stream(), which is just Collection.stream():

default Stream<E> stream() {
    return StreamSupport.stream(spliterator(), false);
}

So, you'll have to mock the spliterator() method as well, and probably a few others, too! Alternatively, tell Mockito to call default methods:

Can you make mockito (1.10.17) work with default methods in interfaces?

A comment on mocking in general

I'm not convinced that mocking the jOOQ API is a very good idea. The jOOQ API is vast, and you'll likely forget to mock this or that method as this question here has aptly shown. With your current setup, you're planning on updating your mock every time you project a new column? E.g. you're doing this:

when(recordMock.get(DEVICEID.getName()).thenReturn(deviceId);

What if the column is renamed? Or another column is projected? You'll have to update this test. That feels like quite the chore, and it's very error prone.

While jOOQ itself has JDBC mocking capabilities, please consider the bold disclaimer on that manual page:

Disclaimer: The general idea of mocking a JDBC connection with this jOOQ API is to provide quick workarounds, injection points, etc. using a very simple JDBC abstraction. It is NOT RECOMMENDED to emulate an entire database (including complex state transitions, transactions, locking, etc.) using this mock API. Once you have this requirement, please consider using an actual database product instead for integration testing, rather than implementing your test database inside of a MockDataProvider

When working with databases, it's usually best to resort to running integration tests, see the following resources for some details:

• Integration testing with Jooq
• Using H2 as a Test Database Product with jOOQ
• How to Integration Test Stored Procedures with jOOQ
• Using Testcontainers to Generate jOOQ Code

Of course, you can write a few smoke tests to ensure jOOQ works correctly if you don't trust jOOQ (jOOQ being an external dependency). But the jOOQ unit and integration tests are vast, so in general, you should be able to trust core types like Result or Record to do the right thing for you. What you really want to test is your query correctness, and that, you can only integration test against an actual database instance.

Technically speaking both "mocks" and "spies" are a special kind of "test doubles".

Mockito is unfortunately making the distinction weird.

A mock in mockito is a normal mock in other mocking frameworks (allows you to stub invocations; that is, return specific values out of method calls).

A spy in mockito is a partial mock in other mocking frameworks (part of the object will be mocked and part will use real method invocations).

Use a Hamcrest matcher, as shown in the documentation:

when(carFinderMock.find(argThat(isRed()))).thenReturn(car1);

where isRed() is defined as

private Matcher<MappingFilter> isRed() {
    return new BaseMatcher<MappingFilter>() {
        // TODO implement abstract methods. matches() should check that the filter is RED.
    }
}

With that configuration (and it's correct), the code that uses Mockito needs to be in src/test/java rather than src/main/java. testCompile defines compile dependencies for src/test/java.