Mockito does not initialize mock in test running with JUnit 5 in @BeforeAll annotated method

Question

Mockito does not initialize a mock run with the JUnit 5 in a @BeforeAll annotated method. It works if I change the init's method annotation to @BeforeEach. Tests are run within IntelliJ IDEA.

My test class :

@ExtendWith(MockitoExtension.class)
@TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class MyTest {
    
    private MyMockedClass myMockedClass;

    @BeforeAll
    public void init() {
        when(myMockedClass.getSomething()).thenReturn(something); // Mock is not initialized, getting NPE on test

Dependencies (only related ones are shown, others omitted for brevity):

[INFO] --- maven-dependency-plugin:2.10:tree (default-cli) @ XXX ---
[INFO] +- org.mockito:mockito-core:jar:3.6.28:test
[INFO] |  +- net.bytebuddy:byte-buddy:jar:1.10.18:compile
[INFO] |  +- net.bytebuddy:byte-buddy-agent:jar:1.10.18:test
[INFO] |  \- org.objenesis:objenesis:jar:3.1:test
[INFO] +- org.mockito:mockito-junit-jupiter:jar:3.6.28:test
[INFO] |  \- org.junit.jupiter:junit-jupiter-api:jar:5.7.0:test
[INFO] |     +- org.apiguardian:apiguardian-api:jar:1.1.0:test
[INFO] |     +- org.opentest4j:opentest4j:jar:1.2.0:test
[INFO] |     \- org.junit.platform:junit-platform-commons:jar:1.7.0:test
[INFO] +- org.springframework.boot:spring-boot-starter-test:jar:2.4.1:test
[INFO] |  +- org.junit.jupiter:junit-jupiter:jar:5.7.0:test
[INFO] |  |  +- org.junit.jupiter:junit-jupiter-params:jar:5.7.0:test
[INFO] |  |  \- org.junit.jupiter:junit-jupiter-engine:jar:5.7.0:test
[INFO] |  |     \- org.junit.platform:junit-platform-engine:jar:1.7.0:test

Have you annotated the `private MyMockedClass myMockedClass;` field with the `@Mock` annotation? As far as I remember the `@Mock` annotation is still required for Mockito to initialize mocks. — Thomas Kläger, Jan 02 '21 at 20:22
Just out of curiosity: why do you need mocks in the `@BeforeAll` method? Why are mocks in the `@BeforeEach` method not sufficient? — Thomas Kläger, Jan 03 '21 at 09:45
@ThomasKläger I am providing mock behavior (answer) in `@BeforeAll`. I do not want to re-run init method for each unit test. — fg78nc, Jan 03 '21 at 18:41

score 14 · Answer 1 · answered Jan 02 '21 at 22:04

The MockitoExtension class implements the BeforeEachCallback but not the BeforeAllCallback from JUnit-Jupiter-API. It does therefore not provide any additional behaviour for @BeforeAll annotated methods.

Source extract of MockitoExtension

public class MockitoExtension implements BeforeEachCallback, AfterEachCallback, ParameterResolver {

score 7 · Answer 2 · edited Aug 26 '21 at 17:10

7

You're missing the initialization of the myMockedClass. Note that you can't use a @Mock annotation for it, because the @BeforeAll method would be run before that annotation is used to initialize the mocked object, and you'd have to resort to explicitly calling Mockito.mock:

@BeforeAll
public void init() {
    myMockedClass = mock(MyMockedClass.class); // Here
    when(myMockedClass.getSomething()).thenReturn(something);
}

edited Aug 26 '21 at 17:10

GalAbra

5,048
4
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answered Jan 02 '21 at 19:54

Mureinik

297,002
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3

`@BeforeAll` can be non-static (and I need it to be non-static in my case) if class is annotated with `@TestInstance(TestInstance.Lifecycle.PER_CLASS)` – fg78nc Jan 02 '21 at 20:06
@fg78nc arg, that was dumb of me, sorry about that. The problem is probably simpler - you didn't initialize the mock object. See my edited answer. – Mureinik Jan 02 '21 at 20:22
5

That's the essence of the question : Mockito should initialize mocks automatically by the virtue of presence of `@ExtendWith(MockitoExtension.class)` annotation. I do not want to initialize mock explicitly. As mentioned it works for with `@BeforeEach`. – fg78nc Jan 02 '21 at 20:26
@fg78nc The same snippet fails with the same `NullPointerException` even if you change it to a `BeforeEach` method. `MockitoExtension` won't mock test members that aren't annotated with `@Mock` (or something similar). – Mureinik Jan 02 '21 at 20:29

score -1 · Answer 3 · answered Aug 04 '22 at 10:49

it's a bit old but I found a solution that works for me :

public class MockitoExtensionBeforeAll extends MockitoExtension implements BeforeAllCallback, AfterAllCallback {

@Override
public void beforeAll(ExtensionContext context) {
    super.beforeEach(context);
}

@Override
public void afterAll(ExtensionContext context) {
    super.afterEach(context);
}

@Override
public void beforeEach(ExtensionContext context) {

}

@Override
public void afterEach(ExtensionContext context) {

}

}

Mockito does not initialize mock in test running with JUnit 5 in @BeforeAll annotated method

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