Testing in K1 Locally

From IntelliJ IDEA version 2025.3, K2 mode is the default. If you need to test the plugin in K1 mode locally, pass the -Didea.kotlin.plugin.use.k1=true VM option to the IntelliJ IDEA run configuration or to the test task.

When using the IntelliJ Platform Gradle Plugin, you can specify the option directly in the build.gradle.kts file.

To run in a debug IntelliJ IDEA instance, submit the option to the RunIdeTask:

tasks.named<RunIdeTask>(“runIde”) {
    jvmArgumentProviders += CommandLineArgumentProvider {
        listOf(“-Didea.kotlin.plugin.use.k1=true”)
    }
}

To run tests against the Kotlin IntelliJ IDEA plugin in the K1 mode, add the option to the test task:

tasks.test {
    jvmArgumentProviders += CommandLineArgumentProvider {
        listOf(“-Didea.kotlin.plugin.use.k1=true”)
    }
}

Last modified: 24 October 2025