Mockito ExceptionInInitializer error with simple DAO

Question

I'm starting to use Mockito with Junit 4.12, Java EE, i need to test this service method in a CQRS program, i want to Mock the UserDAO (We are dealing with users) and then assert some properties.

This is what i made so far:

@RunWith(MockitoJUnitRunner.class)
public class UserCommandServiceTest {

    @InjectMocks
    private UserCommandService userCommandService;

    @Mock
    private UserDAO userDAO;

    @Before
    public void init() {

        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void testCreation() throws Exception {
        User test = new User();
        test.setUsername("test_username");
        Mockito.when(userDAO.findById(Mockito.anyInt())).thenReturn(test);
        assertEquals(0, 0);

    }

}

The problem is not the test itself (as you can see there is an AssertEquals(0,0)), it is the fact that it just not run, it gives me ExceptionInInitializer when i mock the DAO, I don't know if it useful to post the DAO code, but it is just a simple CRUD class with JPA annotations.

Here i post the full trace:

java.lang.ExceptionInInitializerError
    at org.mockito.cglib.core.KeyFactory$Generator.generateClass(KeyFactory.java:167)
    at org.mockito.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
    at org.mockito.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:217)
    at org.mockito.cglib.core.KeyFactory$Generator.create(KeyFactory.java:145)
    at org.mockito.cglib.core.KeyFactory.create(KeyFactory.java:117)
    at org.mockito.cglib.core.KeyFactory.create(KeyFactory.java:109)
    at org.mockito.cglib.core.KeyFactory.create(KeyFactory.java:105)
    at org.mockito.cglib.proxy.Enhancer.<clinit>(Enhancer.java:70)
    at org.mockito.internal.creation.cglib.ClassImposterizer.createProxyClass(ClassImposterizer.java:95)
    at org.mockito.internal.creation.cglib.ClassImposterizer.imposterise(ClassImposterizer.java:57)
    at org.mockito.internal.creation.cglib.ClassImposterizer.imposterise(ClassImposterizer.java:49)
    at org.mockito.internal.creation.cglib.CglibMockMaker.createMock(CglibMockMaker.java:24)
    at org.mockito.internal.util.MockUtil.createMock(MockUtil.java:33)
    at org.mockito.internal.MockitoCore.mock(MockitoCore.java:59)
    at org.mockito.Mockito.mock(Mockito.java:1285)
    at org.mockito.internal.configuration.MockAnnotationProcessor.process(MockAnnotationProcessor.java:33)
    at org.mockito.internal.configuration.MockAnnotationProcessor.process(MockAnnotationProcessor.java:16)
    at org.mockito.internal.configuration.DefaultAnnotationEngine.createMockFor(DefaultAnnotationEngine.java:43)
    at org.mockito.internal.configuration.DefaultAnnotationEngine.process(DefaultAnnotationEngine.java:66)
    at org.mockito.internal.configuration.InjectingAnnotationEngine.processIndependentAnnotations(InjectingAnnotationEngine.java:71)
    at org.mockito.internal.configuration.InjectingAnnotationEngine.process(InjectingAnnotationEngine.java:55)
    at org.mockito.MockitoAnnotations.initMocks(MockitoAnnotations.java:108)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl$1.withBefores(JUnit45AndHigherRunnerImpl.java:27)
    at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:276)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
    at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:93)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:529)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:756)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @224edc67
    at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:357)
    at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
    at java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:199)
    at java.base/java.lang.reflect.Method.setAccessible(Method.java:193)
    at org.mockito.cglib.core.ReflectUtils$2.run(ReflectUtils.java:57)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:312)
    at org.mockito.cglib.core.ReflectUtils.<clinit>(ReflectUtils.java:47)
    ... 40 more

I'm working with mockito 1.10.19.

Answer 1

Issue in Android Studio after JDK migration

java.lang.ExceptionInInitializerError at org.mockito.cglib.core.KeyFactory$Generator.generateClass(KeyFactory.java:167) at org.mockito.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25) at org.mockito.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:217) at org.mockito.cglib.core.KeyFactory$Generator.create(KeyFactory.java:145)

I also face this issue in Android Studio after Migrating Java JDK 17, Just Add below line inside app>build.gradle

tasks.withType(Test) {
    jvmArgs('--add-opens=java.base/java.lang=ALL-UNNAMED')
}

Gradle Reference https://docs.gradle.com/enterprise/test-distribution/#accessing_jdk_internal_classes_from_your_tests

Answer 2

Solved

For the guys facing my problem, the solution is to use only this maven dependency:

    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-core</artifactId>
        <version>4.2.0</version>
        <scope>test</scope>
    </dependency>