Forking and ordering tests in Sbt 0.13.x - scala

Question

Here is how it was configured for Sbt 0.12.x:
parallelExecution in test := false
testGrouping in Test <<= definedTests in Test map { tests =>
tests.map { test =>
import Tests._
import scala.collection.JavaConversions._
new Group(
name = test.name,
tests = Seq(test),
runPolicy = SubProcess(javaOptions = Seq(
"-server", "-Xms4096m", "-Xms4096m", "-XX:NewSize=3584m",
"-Xss256k", "-XX:+UseG1GC", "-XX:+TieredCompilation",
"-XX:+UseNUMA", "-XX:+UseCondCardMark",
"-XX:-UseBiasedLocking", "-XX:+AlwaysPreTouch") ++
System.getProperties.toMap.map {
case (k, v) => "-D" + k + "=" + v
}))
}.sortWith(_.name < _.name)
}
During migration to Sbt 0.13.x I get the following error:
[error] Could not accept connection from test agent: class java.net.SocketException: socket closed
java.net.SocketException: socket closed
at java.net.DualStackPlainSocketImpl.accept0(Native Method)
at java.net.DualStackPlainSocketImpl.socketAccept(DualStackPlainSocketImpl.java:131)
at java.net.AbstractPlainSocketImpl.accept(AbstractPlainSocketImpl.java:398)
at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:199)
at java.net.ServerSocket.implAccept(ServerSocket.java:530)
at java.net.ServerSocket.accept(ServerSocket.java:498)
at sbt.ForkTests$$anonfun$mainTestTask$1$Acceptor$2$.run(ForkTests.scala:48)
at java.lang.Thread.run(Thread.java:745)
Migration changes are just updates in sbt & plugin versions.
Are there any other approaches to forking and ordering of tests in Sbt 0.13.x to overcome that exception?

Answer 1

Works fine on Linux and Mac OS.
Got error on Windows because of limit of classpath length that prevents launching of test agent instance with following error in System.err:
Error: Could not find or load main class sbt.ForkMain

Answer 2

I also got this error when moving to Scala repo to sbt version sbt.version = 1.3.8 (previously 1.2.8 was ok). Strangely worked fine on my mac, but failed on teamcity linux build agents.
Fix for me was to set
fork := false,
in build.sbt.
Not sure why repo had it previously set to fork := true (guess it was cut/paste from somewhere else as no strong reason for this in this repo), but this change resolved the issue. Locally on my mac also runs a few seconds faster now.
See here for background
https://www.scala-sbt.org/1.0/docs/Forking.html