Errors when executing Runtime subproject tests on Windows

[gslowikowski]

When scalac-scoverage-runtime.jvm and scalac-scoverage-runtime.js are being built concurrently, they are trying to create the same files (in the same directories).

This leads to a deadlock, but only on Windows (why?).

Error messages look like this:

[error] scala.scalajs.js.JavaScriptException: Error: EBUSY: resource busy or locked, unlink 'target\invoker-test.measurement0\scoverage.measurements.51'
[error] 	at <jscode>.Object.unlinkSync(fs.js:975)
[error] 	at scalajssupport.NodeFile.$delete([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:21891)
[error] 	at scoverage.InvokerMultiModuleTest.deleteMeasurementFiles([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:56328)
[error] 	at <jscode>.{anonymous}()([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:56094)
[error] 	at scala.scalajs.runtime.AnonFunction0.apply([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:28672)
[error] 	at org.scalatest.BeforeAndAfter.runTest([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:6177)
[error] 	at scoverage.InvokerMultiModuleTest.runTest([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:56336)
[error] 	at <jscode>.{anonymous}()([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:53960)
[error] 	at scala.scalajs.runtime.AnonFunction2.apply([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:28732)
[error] 	at org.scalatest.Engine.traverseSubNodes$1([path-to-project-root]\scalac-scoverage-runtime\js\target\scala-2.12\scalac-scoverage-runtime-test-fastopt.js:7291)

The problem is a consequence of changing Rhino Javascript implementation used in tests to default NodeJS one in commit cfb968c#diff-fdc3abdfd754eeb24090dbd90aeec2ce

The simple workaround is to set fork in Test := true for scalac-scoverage-runtime.jvm (for .js module setting fork to true is not allowed).

I don't like this solution, but will use it for now.

Waiting for better idea.

[ckipp01]

Tests have now been added for windows. If this pops up again I'll reopen.