Tests work from within VS Code, but not via the sbt console

[nchammas]

I've successfully loaded a Scala project into VS Code with Metals, and can build everything fine. I can also run tests from within the VS Code UI successfully.

However, if I try to run these same tests by starting sbt and then running something like testOnly com...SomeTest in the sbt console, I get this:

> something/testOnly com.something.*
[info] Compiling 1 Scala source to .../target/scala-2.11/classes ...
Unrecognized VM option 'CMSClassUnloadingEnabled'
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
[error] Could not accept connection from test agent: class java.net.SocketException: Socket closed
[error] stack trace is suppressed; run last something / Test / testOnly for the full output

The full exception is:

[error] Could not accept connection from test agent: class java.net.SocketException: Socket closed
[error] java.net.SocketException: Socket closed
[error]         at java.base/sun.nio.ch.NioSocketImpl.endAccept(NioSocketImpl.java:689)
[error]         at java.base/sun.nio.ch.NioSocketImpl.accept(NioSocketImpl.java:762)
[error]         at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:684)
[error]         at java.base/java.net.ServerSocket.platformImplAccept(ServerSocket.java:650)
[error]         at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:626)
[error]         at java.base/java.net.ServerSocket.implAccept(ServerSocket.java:583)
[error]         at java.base/java.net.ServerSocket.accept(ServerSocket.java:540)
[error]         at sbt.ForkTests$Acceptor$1$.run(ForkTests.scala:71)
[error]         at java.base/java.lang.Thread.run(Thread.java:832)

This used to work until I installed Metals, so I suspect Bloop is somehow the cause of this problem. Otherwise, what I do in an independent terminal session shouldn't have any relationship to what I'm doing in VS Code. Before trying Metals, I was able to load this project in IntelliJ and simultaneously run tests via the sbt console in a separate terminal session without issue.

What should I do to troubleshoot?

The project runs on sbt 1.3.13 and Scala 2.11.12.

[tgodzik]

It seems it's failing to start the forked test process due to CMSClassUnloadingEnabled, but Metals does not add that option. Do you know where is it coming from? It shouldn't also come from Bloop really.

[nchammas]

Oh... Interesting. That's in our build.sbt. I commented it out and can now run the tests via the sbt console.

Sorry, I feel silly. Scala newbie so I just glossed over the details of the output.

The fact that this worked for me until I tried Metals convinced me that Metals was somehow the cause, but I guess something else is going on.

[tgodzik]

No worries, I would also think it's connected, however I really have no idea why it would come up at the same time..

[nchammas]

OK, I got to the bottom of it. Compare:

$ java -version
openjdk version "1.8.0_282"

$ sbt
[info] welcome to sbt 1.3.13 (N/A Java 15.0.1)

I'm guessing that when I installed Metals, Java 15 somehow ended up on sbt's path.

After normalizing my Java environment using SDKMAN (suggested to me by my co-workers), sbt points to the expected Java version (1.8) and the original build.sbt once again works as-is.