Test framework quit unexpectedly - can't find a class by name


The error message


Exception in thread "main" java.lang.NoClassDefFoundError: org/junit/platform/launcher/TestIdentifier
    at com.intellij.junit5.JUnit5IdeaTestRunner.<clinit>(JUnit5IdeaTestRunner.java:72)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:315)
    at com.intellij.rt.junit.JUnitStarter.getAgentClass(JUnitStarter.java:244)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:225)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.lang.ClassNotFoundException: org.junit.platform.launcher.TestIdentifier
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
    ... 6 more



Steps to reproduce

Create a brand new IDE plugin

Update build.gradle.kts per instructions here: https://kotlinlang.org/docs/jvm-test-using-junit.html#add-the-code-to-test-it

Create the tests using the UI, per the instructions

Try to run the tests


The above steps _will_ work with a different type of project.

The issue _seems_ to stem from the intellij plugin 

id("org.jetbrains.intellij") version "1.8.0"

If i delete this (and all associated elements from the gradle), i can run tests.

Any advice on how to make these two co-exist would be nice.



IntelliJ IDEA 2022.2.2 (Ultimate Edition)
Build #IU-222.4167.29, built on September 13, 2022
Licensed to Jeffrey Reynolds
Subscription is active until May 15, 2023.
Runtime version: 17.0.4+7-b469.53 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Linux 5.19.9-zen1-1-zen
GC: G1 Young Generation, G1 Old Generation
Memory: 2048M
Cores: 32
Non-Bundled Plugins:
    org.antlr.intellij.plugin (1.19.2)
    org.jetbrains.idea.grammar (2021.1.2)
    PsiViewer (222-SNAPSHOT)
    com.intellij.bigdatatools (222.3345.33)

Kotlin: 222-1.7.10-release-334-IJ4167.29
Current Desktop: KDE


Hi Jeffrey,

Please try the newest Gradle IntelliJ Plugin: 1.9.0 and let us know if it solves the issue.

If the issue still occurs, it would be perfect if you shared the project where we can quickly reproduce it. Thanks.



Upgrading to 1.9.0 did not make a difference.  

I've uploaded a sample project that should recreate the issue here: https://github.com/taekahn/intellij-plugin-bug

Please let me know if you have any issues.

Thank you.


Hi Jeffrey,

Please add the following dependency:


Also, the depdency to junit-jupiter seems unnecessary, so please remove it:


That seems to work.



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