Mill seems to attempt to run scala JS code on JVM?

[Quafadas]

I have this sub-module configured https://github.com/Quafadas/scautable/tree/submodule.

package build.scautable

import mill._
import mill.scalalib._
import mill.scalajslib._
import mill.scalajslib.api._
import build.Config

object `package` extends RootModule {

  trait Common extends ScalaModule {
    def scalaVersion = Config.scalaVersion

    override def ivyDeps = super.ivyDeps() ++ Agg(
      Config.scalatags,
      Config.oslib,
      Config.fansi
    )
  }

  trait CommonJS extends Common with ScalaJSModule {
    def scalaJSVersion = "1.19.0"
    override def ivyDeps = super.ivyDeps() ++ Agg(
      ivy"org.scala-js::scalajs-dom::2.8.0",
      ivy"org.scala-js::scalajs-java-securerandom::1.0.0".withDottyCompat(scalaVersion()),
      Config.laminar
    )
  }

  trait SharedModule extends Common with PlatformScalaModule

  trait SharedTest extends SharedModule with TestModule.Munit {
    override def ivyDeps = super.ivyDeps() ++
      Agg(
        ivy"org.scalameta::munit::1.1.1"
      )
  }

  object js extends CommonJS with SharedModule with build.PublishModule

  object test extends Module {
    object js extends CommonJS with SharedTest  {
      override def moduleDeps: Seq[JavaModule]  = Seq(build.scautable.js)
    }
  }

When I run this command;

scautable.test.js.test

I get this error.

[138]   at munit.internal.PlatformCompat$.newRunner(PlatformCompat.scala:72)
[138]   at munit.internal.junitinterface.JUnitTask.execute(JUnitTask.scala:39)
[138]   at munit.internal.junitinterface.JUnitTask.execute(JUnitTask.scala:31)
[138]   at mill.testrunner.TestRunnerUtils$.executeTasks(TestRunnerUtils.scala:150)
[138]   at mill.testrunner.TestRunnerUtils$.runTasks(TestRunnerUtils.scala:209)
[138]   at mill.testrunner.TestRunnerUtils$.runTestFramework0(TestRunnerUtils.scala:226)
[138]   at mill.testrunner.TestRunnerMain0$.main0(TestRunnerMain0.scala:39)
[138]   at mill.testrunner.TestRunnerMain0.main0(TestRunnerMain0.scala)
[138]   at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
[138]   at java.base/java.lang.reflect.Method.invoke(Method.java:580)
[138]   at mill.testrunner.entrypoint.TestRunnerMain.main(TestRunnerMain.java:42)
[138] Caused by: java.lang.ClassCastException: class scala.scalajs.js.Object cannot be cast to class scala.scalajs.js.Dictionary (scala.scalajs.js.Object and scala.scalajs.js.Dictionary are in unnamed module of loader 'app')
[138]   at scala.scalajs.js.Dictionary$.empty(Dictionary.scala:60)
[138]   at scala.scalajs.reflect.Reflect$.<clinit>(Reflect.scala:72)
[138]   ... 11 more
[138] java.lang.ExceptionInInitializerError

My enquiry on discord, suggests that this is a symptom, of attempting to run scalaJS code, on the JVM.

https://discord.com/channels/632150470000902164/635668814956068864/1370034019688775832

I cannot see, how this is misconfigured though. Is it? Could this be a bug?

[lolgab]

It seems that your test module doesn't extend TestScalaJSModule, which overrides the testTask task to use the Scala.js test runner.
When a test module is a inner module of a ScalaJSModule you usually extend ScalaJSTests, but here your module is not inside another ScalaJSModule, so you need to extend TestScalaJSModule

[Quafadas]

It is exactly this. Thankyou 🙏 !