JSEnvs are only closed after all tests are run in aggregate project

As stated in the README

Executing test will open several browser windows and close them all before the end of the tests.

This behavior seems to cause spawning a lot of browser processes when running test in an aggregate project, which are only stopped after all tests have finished.

Since switching to Firefox in https://github.com/softwaremill/tapir/pull/860 due to scala-js/scala-js-env-selenium#119/#105, this causes issues on memory constrained CI runners. Firefox seems to be a bit more memory hungry than Chrome, so we’re only seeing this now but the behavior is the same in Chrome as well.

Is there a way to terminate browser processes after each test run or after the tests of single subproject have finished, when running test on an aggregate project in sbt?

Note that in parallel execution is already disabled in the build:

concurrentRestrictions in Global += Tags.limit(Tags.Test, 1),
Test / parallelExecution := false

[gzm0]

This is unfortunately another shortcoming of sbt.testing._ (although a much more subtle one): There is no resource cleanup hook for resources shared between multiple Frameworks.

In Scala.js’ sbt plugin, we might have the option to intercept sbt’s testing infrastructure more deeply and get a better point to call TestAdapter#close().

The obvious downside of this would of course be that we’d rely on much more internal details of how sbt executes tests.

IMHO, this is a Scala.js core issue (notably, it is, in my opinion, not an issue with the JSEnv interface). Unless there are objections, I’ll transfer this issue to scala-js/scala-js.

[gzm0]

After having attempted to build said heuristic, I’m not comfortable proceeding: From what I can see, it has the potential to worsen currently working use cases (notably the workaround to this very issue).