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

I'm getting following exception once tests is started:

    Testcase: treeCtorArgumentTest(com.xythos.client.drive.cachedtree.CachedTreeTest):	Caused an ERROR
Could not initialize plugin: interface org.mockito.plugins.MockMaker
java.lang.IllegalStateException: Could not initialize plugin: interface org.mockito.plugins.MockMaker
	at org.mockito.internal.configuration.plugins.PluginLoader$1.invoke(PluginLoader.java:66)
	at com.sun.proxy.$Proxy7.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:168)
	at org.mockito.internal.creation.MockSettingsImpl.confirm(MockSettingsImpl.java:162)
	at org.mockito.internal.MockitoCore.mock(MockitoCore.java:64)
	at org.mockito.Mockito.mock(Mockito.java:1687)
	at org.mockito.Mockito.mock(Mockito.java:1600)
	at com.xythos.client.drive.cachedtree.CachedTreeTest.setUp(CachedTreeTest.java:51)
Caused by: java.lang.NoClassDefFoundError: net/bytebuddy/dynamic/loading/ClassLoadingStrategy
	at org.mockito.internal.creation.bytebuddy.SubclassByteBuddyMockMaker.<init>(SubclassByteBuddyMockMaker.java:33)
	at org.mockito.internal.creation.bytebuddy.ByteBuddyMockMaker.<init>(ByteBuddyMockMaker.java:22)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at java.lang.Class.newInstance(Class.java:442)
	at org.mockito.internal.configuration.plugins.PluginLoader.loadPlugin(PluginLoader.java:54)
	at org.mockito.internal.configuration.plugins.PluginRegistry.<init>(PluginRegistry.java:18)
	at org.mockito.internal.configuration.plugins.Plugins.<clinit>(Plugins.java:17)
	at org.mockito.internal.util.MockUtil.<clinit>(MockUtil.java:24)
Caused by: java.lang.ClassNotFoundException: net.bytebuddy.dynamic.loading.ClassLoadingStrategy
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

This is my test:

package com.xythos.client.drive.cachedtree;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.junit.MockitoJUnitRunner;

@RunWith(MockitoJUnitRunner.class)

    public class CachedTreeTest {
    
        public CachedTreeTest() {
        }
    
        @Test
        public void treeCtorArgumentTest() {
    	somemock m = mock(SomeClass.class);
        }
    }

I'm using NetBeans 8.2. I've downloaded mockito-core-2.7.0.jar, and then I select "Test Libraries"->"Add Jar" and added mockito-core-2.7.0.jar.

Classpath and everything looks ok, I',m still getting exception.

Any advice?

If you are using powermock ensure that your dependencies point to:

org.powermock:powermock-api-mockito2

instead of

org.powermock:powermock-api-mockito

Missing reference to:

• byte-buddy-1.6.5.jar
• byte-buddy-agent-1.6.5.jar
• objenesis-2.5.jar

Since Mockito 2.0.2 beta, Mockito-core has dependencies.

I had Byte Buddy on classpath (is transitive dep of Mockito 2.8.9) and still got the exception. Reason for me was that I ran the Unit tests with JRE instead of JDK. Switching to JDK worked for me.

This problem with Mockito2 occurs if you enable the option to mock final classes.

> This means when in your test/resources/mockito-extensions directory > you have the file called org.mockito.plugins.MockMaker with the > following content mock-maker-inline.

In that case byte-buddy, which is a transitive dependency for mockito-core, has the problem to attach own agent to the java process. But the problem occurs only when you use JRE.

The solution would be either:

• Use JDK instead of JRE

or

• add -javaagent:byte-buddy-agent-*.jar as a VM option

I had the same problem - same stacktrace appear in my log. It is typically problem with project setup... OR
The problem can be in the bytebuddys JARs if these were not downloaded correctly.
When I try to check class ClassLoadingStrategy manually then I get zip error.

In that case it is just enough manually delete the Byte Buddy from local maven directory, usually located at:
{home}/.m2/repository/net/bytebuddy/

The next try to run project or test they will be downloaded again and should work as expected.

Unfortunatelly common Java ClassLoader faces in the same way when class or jar missing as well as the jar is corrupted.

Well, after a lot of research , solution for me is super simple :

update Mockito lib version to latest

dependencies {
    testImplementation 'org.mockito:mockito-core:3.10.0'
    androidTestImplementation 'org.mockito:mockito-android:3.10.0'
}

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.

In my case, after removing mockito-core, the test worked!

<dependency>
	<groupId>org.mockito</groupId>
	<artifactId>mockito-core</artifactId>
	<version>${mockito.version}</version>
	<scope>test</scope>
</dependency>

My version is here, and JDK is 1.8.0_121.

<properties>
	<powermock.version>2.0.7</powermock.version>
	<mockito.version>2.8.9</mockito.version>
</properties>

Now my dependencies are:

• powermock-api-mockito2
• powermock-module-junit4

For android development you need to import a couple of things:

 dependencies {
   testCompile "org.mockito:mockito-core:+"
   androidTestCompile "org.mockito:mockito-android:+"
 }

could not find any reference of this but this is the only one that has worked for me.

I encountered this issue and solved it by bumping my version of org.mockito.mockito-core to the latest release. I had been using an older release for quite some time.

In my case, I was working on a project that does not use the maven build system. So this is what worked for me.

• Navigated to the maven repo for mockito (used v2.26): https://mvnrepository.com/artifact/org.mockito/mockito-core/2.26.0. I downloaded the jar.
• On the same page at the bottom, I looked up the dependencies. For mockito 2.26.0, these dependencies are:
• Byte Buddy v.1.9.10 (https://mvnrepository.com/artifact/net.bytebuddy/byte-buddy/1.9.10)
• Byte Buddy Java Agent v1.9.10 (https://mvnrepository.com/artifact/net.bytebuddy/byte-buddy-agent/1.9.10)
• Objenesis v2.6 (https://mvnrepository.com/artifact/org.objenesis/objenesis/2.6) I downloaded the jar files for the above mockito dependencies In Eclipse I created a user library containing the four jar file and added it to my project.

NB: (creating the library is optional, you can add the jars directly to your project build path)

Hope this helps someone.

Delete the "byte-buddy-1.7.11.jar" manually from the maven repository path which appears in the error. Maven update the project and the issue will be resolved. Tried and worked for me.

Mockito 2 requires dependencies. Adding the two ByteBuddy dependencies below. solved the issue for me:

• byte-buddy-x.x.xx.jar
• byte-buddy-agent-x.x.xx.jar

In my case I include jar files in the project, which can be found at: https://bintray.com/raphw/maven/ByteBuddy/

If you need it for a Maven project, simply add:

<dependency>
  <groupId>net.bytebuddy</groupId>
  <artifactId>byte-buddy</artifactId>
  <version>1.9.14</version>
  <type>pom</type>
</dependency>

I solved this problem by removing jmockit in POM XML for Maven. After that my Junit 5 tests work perfectly.

	<dependency>
		<groupId>org.jmockit</groupId>
		<artifactId>jmockit</artifactId>
		<version>1.41</version>
		<scope>test</scope>
	</dependency>

With this dependency I always get an error like:

java.lang.IllegalStateException: Could not initialize plugin: interface org.mockito.plugins.MockMaker (alternate: null)
...

Could not initialize inline Byte Buddy mock maker. (This mock maker is not supported on Android.)
...

Caused by: com.sun.tools.attach.AttachNotSupportedException: no providers installed
...

For me the problem was that IntelliJ ran the test as integration test. So I needed to create JUnit test manually

You're probably having issues with manually adding dependencies to your project. Take note of the mockito-core jar version being used in your project.

Visit this mvn repository link

https://mvnrepository.com/artifact/org.mockito/mockito-core/{replace-with-your-mockito-core-version}

Move to the compile dependencies sections down below in the mvn repository page, download all the appropriate version of the dependencies mockito-core needs.

As of answering this question: > byte-buddy

> byte-buddy-agent

> objenesis

Add all to the project together with mockito-core and run tests.

in my case, some abnormal env setting will also lead to this error:

in ubuntu 16.04, java and javac had been update-alternatives to 7 but $JAVA_HOME had been wrongly set to 8

i remove the $JAVA_HOME, and everything back to normal

Adding a bnd aspect to this

Adding on to Paskas' answer, you also have to include the dependencies in the cnf maven repository, if you're using one (like my cnf/central.mvn).

org.mockito:mockito-core:2.21.0
net.bytebuddy:byte-buddy:1.8.15
net.bytebuddy:byte-buddy-agent:1.8.15
org.objenesis:objenesis:2.6

and for convenient referencing, you can include a bnd variable in your cnf/build.bnd

mockito: org.mockito:mockito-core; version=2.21.0,\
         net.bytebuddy:byte-buddy; version=1.8.15,\
         net.bytebuddy:byte-buddy-agent; version=1.8.15,\
         org.objenesis:objenesis; version=2.6

and in your project's bnd file

-testpath:\
    ${mockito}

I have had the same problem in one existing project. I used java 8 and additionally installed java 10. So I started get this exception. I deinstalled java 10, it has not helped. I deleted bytebuddy jars from maven repo, it has not helped. Only after complete removal of all jars from maven repo I could compile project again.

Remove version declaration works for me:

Example:

	<dependency>
		<groupId>org.mockito</groupId>
		<artifactId>mockito-core</artifactId>
		<version>2.8.9</version>
		<scope>test</scope>
	</dependency>

remove 2.8.9

After:

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

It may due to version issue between jar packages of this dependency.

Not the answer to the original poster, since s/he's using Netbeans, but in Eclipse I needed to do "Maven -> Update Project" in order to get tests working again.

It worked for me After I removed bytebuddy folder from ${home}.m2\repository\net\bytebuddy and removed byte-buddy-agent,byte-buddy and objenesis dependency from pom.xml

I had the same issue, got resolved by adding jcenter in repositories and mockito dependecies.

repositories {
    jcenter()
 }
 dependencies {
    testImplementation 'org.mockito:mockito-core:3.7.7'
    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'
 }

    androidTestImplementation 'org.mockito:mockito-core:2.19.0' 
testImplementation "org.mockito:mockito-core:2.19.0"//game changer for your question

This second line was a game-changer, android Test implementation and test implementation are not the same test set (android test implementation is a test set for physical devices or emulators)... you may have dependency for one and writing code, but if you run the different test (local in the android studio without emulator) it will fail (unless..:)

happy testing

In my case, removing:

{home}/.m2/repository/org/robolectric/

solved the issue. Next time it runs, it will download those files again.

• PowerMock doesn't work with sonar in the first step, the cause of the problem is the combination of powermock and jacoco
• We will not face this issue locally, but if we use sonar for test coverage calculations, the error is as follows

Could not initialize plugin: interface org.mockito.plugins.MockMaker (alternate: null) 

• In PowerMock 2.0.9 version, a workaround for this problem is provided they have added an annotation @PrepareOnlyThisForTest, this provides the ability for the isolation of a particular Test class.
• Apart from that, we need to add delegate the Runner to SpringRunner using @PowerMockRunnerDelegate(SpringRunner.class)

Add Power Mock Dependencies in pom.xml

		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-junit4</artifactId>
			<version>2.0.2</version>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-api-mockito2</artifactId>
			<version>2.0.9</version>
			<scope>test</scope>
		</dependency>

Use the PowerMock Junit Runner for test Class and declare the test class that we’re mocking and delegate SpringRunner

    @RunWith(PowerMockRunner.class)
	@PrepareOnlyThisForTest(ServiceApplication.class)
	@PowerMockRunnerDelegate(SpringRunner.class)
	public class ExampleControllerTest {
		PowerMockito.mockStatic(ServiceApplication.class);
        Mockito.when(ServiceApplication.getStatic()).thenReturn("");

I got the same issue, finally fix it.

It's a long answer, but if you struggling with this issue for a while, hope this can help you.

---

This is my scenario.

Android Unit Test

dependency

-> org.mockito:mockito-core ()

-> org.powermock:powermock-api-mockito2 (mock static class)

-> mockito-inline (enable final class mock)

-> com.nhaarman.mockitokotlin2:mockito-kotlin

---

Root Cause -> check the error log

Issue1 -> Tools.jar dependency missed

In order to use the mock-maker-inline (mockito-inline), it has dependency on Tools.jar. We need the dependency.

here is the link

My error log looks like below

java.lang.RuntimeException: Invoking the beforeTestMethod method on PowerMock test listener org.powermock.api.extension.listener.AnnotationEnabler@49a4bf9a failed.

...

Caused by:
        java.lang.IllegalStateException: Could not initialize plugin: interface org.mockito.plugins.MockMaker (alternate: null)

        ... 

        Caused by:
            java.lang.IllegalStateException: Failed to load interface org.mockito.plugins.MockMaker implementation declared in sun.misc.CompoundEnumeration@3d529098

            ...

            Caused by:
                java.lang.reflect.InvocationTargetException

                ...

               Caused by:
                    org.mockito.exceptions.base.MockitoInitializationException: 
                    Could not initialize inline Byte Buddy mock maker.
                    ...

                    Caused by:
                                java.lang.NullPointerException
                                    at com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:182)

So you can see the last line says attachProvider throw NullPointerException, this attachProvider exists in the tools.jar

class path is com.sun.tools.attach.AttachProvider.

So we need to add the dependency for tools.jar

---

Issue2 -> added wrong dependency for tools.jar

I added a wrong dependency for tools.jar use the MacOS tools.jar as dependency.

But our build machine is Linux platform, So I got this error with diff error log.

Cause JDK has different version with different platforms (MacOS, Linux, Windows)
based on the different platforms `VirtualMachine` has diff implementation (MacOS, Linux, Windows) 

---

Here is the error log

Caused by:
        java.lang.IllegalStateException: Could not initialize plugin: interface org.mockito.plugins.MockMaker (alternate: null)

        ... 

        Caused by:
            java.lang.IllegalStateException: Failed to load interface org.mockito.plugins.MockMaker implementation declared in sun.misc.CompoundEnumeration@3d529098

            ...

            Caused by:
                java.lang.reflect.InvocationTargetException

                ...

               Caused by:
                    org.mockito.exceptions.base.MockitoInitializationException: 
                    Could not initialize inline Byte Buddy mock maker.
                    ...

                    Caused by:
                                java.lang.UnsatisfiedLinkError: sun.tools.attach.BsdVirtualMachine.getTempDir()Ljava/lang/String;
                                    at sun.tools.attach.BsdVirtualMachine.getTempDir(Native Method)
                                    at sun.tools.attach.BsdVirtualMachine.<clinit>(BsdVirtualMachine.java:308)
                                    at sun.tools.attach.BsdAttachProvider.attachVirtualMachine(BsdAttachProvider.java:63)
                                    at com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:208)

You can see here, VirtualMachine find the AttachProvider (BsdAttachProvider) but after that it throw an exception.

So which means we added the dependency, but the dependency is wrong.

---

How to add the tools.jar dependency correctly

(1) add tools.jar file to lib folder (WRONG)

add this `testImplementation fileTree(dir: 'libs', include: ['tools.jar'])` in the gradle file

this is not a good approach, cause our build machine (remote) may use the Linux system, but our local machine (Laptop, PC) may use the MacOS or Windows.

this will cause the Issue2  which I mentioned above

(2) add testImplementation files(org.gradle.internal.jvm.Jvm.current().toolsJar) in gradle file. (WRONG)

this one will throw NullPointerException after gradle 4.X.

(3) add testImplementation files("${System.properties['java.home']}/../lib/tools.jar") in gradle file

it will trying to read the environment virable to get the path for the `tools.jar`

Cause both build machine (remote) and local machine (Laptop, PC) need to configure the JDK to make it work.

So this approach should find it's own path even it's based on diff platform (MacOS, Linux, Windows)

This is the approach I am using, If you have better one, please let me know.

---

Configure Android Studio JDK Location

Don't use the Android Studio Application folder as the JDK location.

Use the JAVA_HOME variable path as the JDK location. (you can type echo JAVA_HOME in the terminal)

Otherwise when you run the unit test it will show this error

Transform's input file does not exist: /Applications/Android Studio.app/Contents/jre/jdk/Contents/lib/tools.jar.

Cause it's Android Studio Application JDK folder doesn't have the tools.jar file. (you can compare the normal configured JDK folder with Android Studio Application Package one)

/Applications/Android Studio.app/Contents/jre/jdk/Contents/Home

After these steps, you should be able to run the unit test.

If you got this org.mockito.exceptions.misusing.NotAMockException when running the unit test

please make sure the mocktio-inline configured correctly.

The issue link (https://github.com/powermock/powermock/issues/992)

Based on the mockito documents (https://github.com/powermock/powermock/wiki/mockito#mockito-mock-maker-inline)

It provides two approaches

1. org.mockito.plugins.MockMaker

2. org/powermock/extensions/configuration.properties

Just try these two approaches, check which one work for you, and just keep one of them.

In my scenario second one works for me.

I also tried this old approach testImplementation 'org.mockito:mockito-inline:X.X.X' it not work for me.

If you use e.g. a different version of spring-boot-test, you might have a bytebuddy version conflict, as mentioned above. To fix, you can use dependencyManagement:

<dependencies>
  <dependency>
     <groupId>org.mockito</groupId>
     <artifactId>mockito-core</artifactId>
     <version>3.11.2</version>
     <scope>test</scope>
  </dependency>
</dependencies>
<dependencyManagement>
  <dependencies>
     <dependency>
        <groupId>net.bytebuddy</groupId>
        <artifactId>byte-buddy</artifactId>
        <version>1.11.10</version>
     </dependency>
     <dependency>
        <groupId>net.bytebuddy</groupId>
        <artifactId>byte-buddy-agent</artifactId>
        <version>1.11.10</version>
     </dependency>
  </dependencies>
</dependencyManagement>

Thanks @Łukasz Rzeszotarski for his solving - it works for me. I just want to add several details about this problem.

This problem appears when i include mockito-inline in my gradle-project, but i don't can refuse of it. It has appear because mockito-inline has follows structure:

META-INF:
    MANIFEST.MF
mockito-exstensions:
    org.mockito.plugins.MockMaker
    org.mockito.plugins.MemberAccessor

where the file org.mockito.plugins.MockMaker contains:

mock-maker-inline

This string is needs for mocking final classes and methods and it causes problems, when you using JRE instead of JDK.

I had this problem when I was using mockitokotlin2. I solved it by using latest version of libraries:

testImplementation 'com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0'
testImplementation 'org.mockito:mockito-inline:4.4.0'

I had the same exception when switch to Java 10 and Spring Boot 2. This dependency combination worked for me:

    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-all</artifactId>
        <version>2.0.2-beta</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>net.bytebuddy</groupId>
        <artifactId>byte-buddy</artifactId>
        <version>1.8.16</version>
    </dependency>
    <dependency>
        <groupId>net.bytebuddy</groupId>
        <artifactId>byte-buddy-agent</artifactId>
        <version>1.8.16</version>
        <scope>test</scope>
    </dependency>

I had the same issue and tryed @Paskas's solution, worked well Junit Test ok at first. added the bytebuddy dependency to my pom.xml:

<dependency>
			<groupId>net.bytebuddy</groupId>
			<artifactId>byte-buddy-dep</artifactId>
			<version>1.9.7</version>
</dependency>

Hope this helps.

Just update to the latest release of org.mockito:mockito-core. Once I did, the errors disappeared!