Missing opens directive in module descriptor

Problem

Using Pioneer on the module path fails with:

java.lang.reflect.InaccessibleObjectException:
  Unable to make org.junitpioneer.jupiter.IssueExtension() accessible:
  module org.junitpioneer does not "opens org.junitpioneer.jupiter" to module org.junit.platform.commons

when using an extension located in package org.junitpioneer.jupiter.

Possible Solution

Open packages that contain types using JUnit Platform’s reflection support to module org.junit.platform.commons.

  opens org.junitpioneer.jupiter to org.junit.platform.commons;

Work around

Pass --add-opens org.junitpioneer/org.junitpioneer.jupiter=org.junit.platform.commons on the command-line or at the right place of your build tool when

[scordio]

Wouldn’t it be sufficient to have a separate src/it module, like @sormuras describes it here:

https://sormuras.github.io/blog/2018-09-11-testing-in-the-modular-world

We use a similar setup in AssertJ (for another purpose: verify what happens with different classpath content) and the main drawback is not being IDE friendly, so maintaining those tests is a bit of a hassle.

We plan to introduce a Maven multi-module project with the next major version and have separate modules for integration testing, automatically detected by the IDE so easier to be maintained.

Something similar (still Maven focused) was also discussed on StackOverflow and Twitter.

The limitations might be strictly connected to the Maven setup (i.e., the maven-invoker-plugin). I am not sure if something similar with Gradle would have the same issues.

[sormuras]

Making IssueExtension, StopwatchExtension, and friends public should also do the trick.