From mobile apps to microservices, from small startups to big enterprises, Gradle helps teams build, automate and deliver better software, faster.

Gradle Community

Can you share the `gradlePlugin {}` configuration? And just double check that the ID of the registered plugin matches the ID that you're applying?

You might have to specify the <https://docs.gradle.org/current/kotlin-dsl/gradle/org.gradle.plugin.devel/-gradle-plugin-development-extension/test-source-sets.html|test source sets>:

```gradlePlugin {
  testSourceSets(...)
}```


Here the `gradlePlugin {}`  configure.
If I move the test into the sourceSet `test` instead of `functionalTest` it works like a charm.
```gradlePlugin {
    plugins {
        register("helm") {
            id = "com.company.gradleplugin.id"
            implementationClass = "com.company.gradleplugin.helm.HelmPlugin"
        }
    }
}```
I will try to setup hint with `testSourceSets(...)`

`withPluginClassPath()` requires that a specific file with the classpath is found in the classpath. This is usually generated by a task that is registered by the <https://docs.gradle.org/current/userguide/java_gradle_plugin.html|https://docs.gradle.org/current/userguide/java_gradle_plugin.html>, do you use that?

Yes, but the file (`build/pluginUnderTestMetadata/plugin-under-test-metatadata.properties`) is not generated by the `functionalTest` task only for the `test` task.

For that <@U02KX5B7EVC> already gave you the solution in his last message.

```gradlePlugin {
    testSourceSet(sourceSets["functionalTest"])
}```


That configuration will add `gradleTestKit()` dependency for you to `...Implementation` and the `pluginUnderTestMetadata` to `...RuntimeOnly`

Or with `testSourceSets(...)` instead, `test` is removed and thus will neither have test kit dependency nor the plugin under test metadata dependency

Which both should not really be necessary for unit tests

Sorry, I completely forgot to say that the proposed solution worked. thanks for the support.