Could not initialize plugin: interface org.mockito.plugins.MockMaker

Question

I\'m getting following exception once tests is started:

    Testcase: treeCtorArgumentTest(com.xythos.client.drive.cachedtree.CachedTreeTest):  Caused an ERR         


        

Answer 1

Problem: PowerMock + Mockito + TestNG + PowerMockTestCase

Sharing my problem/solution in case it helps anybody.

My dependencies were all pointed correctly:

testImplementation 'org.mockito:mockito-core:2.8.47'
testImplementation 'org.powermock:powermock-core:1.7.4'
testImplementation 'org.powermock:powermock-module-testng:1.7.4'
testImplementation 'org.powermock:powermock-api-mockito2:1.7.4'

But I still got the following error:

java.lang.IllegalStateException: Could not initialize plugin: interface org.mockito.plugins.MockMaker

    at org.mockito.internal.configuration.plugins.PluginLoader$1.invoke(PluginLoader.java:66)
    at com.sun.proxy.$Proxy11.isTypeMockable(Unknown Source)
    at org.mockito.internal.util.MockUtil.typeMockabilityOf(MockUtil.java:29)
    at org.mockito.internal.util.MockCreationValidator.validateType(MockCreationValidator.java:22)
    at org.mockito.internal.creation.MockSettingsImpl.validatedSettings(MockSettingsImpl.java:186)
    at org.mockito.internal.creation.MockSettingsImpl.confirm(MockSettingsImpl.java:180)
    at org.mockito.internal.MockitoCore.mock(MockitoCore.java:62)
    at org.mockito.Mockito.mock(Mockito.java:1729)
    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.IndependentAnnotationEngine.createMockFor(IndependentAnnotationEngine.java:38)
    at org.mockito.internal.configuration.IndependentAnnotationEngine.process(IndependentAnnotationEngine.java:62)
    at org.mockito.internal.configuration.InjectingAnnotationEngine.processIndependentAnnotations(InjectingAnnotationEngine.java:57)
    at org.mockito.internal.configuration.InjectingAnnotationEngine.process(InjectingAnnotationEngine.java:41)
    at org.mockito.MockitoAnnotations.initMocks(MockitoAnnotations.java:69)

My test was something as such:

import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.testng.PowerMockTestCase;
import static org.mockito.MockitoAnnotations.initMocks;

@PrepareForTest(MyClass.class)
public class MyTest extends PowerMockTestCase {

    @BeforeTest
    public void init() {
        initMocks(this);
    }
}

As mentioned in this thread, removing the initMocks() method removes the error, but all the mocks become null.

---

✅ Solution: BeforeTest VS BeforeMethod

What I found out for my case is that @BeforeTest was actually posing a problem. Changing it to @BeforeMethod resolved the error.

import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.testng.PowerMockTestCase;
import static org.mockito.MockitoAnnotations.initMocks;

@PrepareForTest(MyClass.class)
public class MyTest extends PowerMockTestCase {

    @BeforeMethod // CHANGE THIS!
    public void init() {
        initMocks(this);
    }
}

My guess is that it is something to do with beans injection; @BeforeTest is executed before any beans got injected while @BeforeMethod is executed after beans injection. Not sure how it really affected though.