Tags.ForkedTestGroup doesn't work

[pauldraper]

http://www.scala-sbt.org/0.13/docs/Testing.html

Control the number of forked JVMs allowed to run at the same time by setting the limit on Tags.ForkedTestGroup tag, which is 1 by default.

---

project/build.properties

sbt.version=0.13.12

build.sbt

concurrentRestrictions in Global := Seq(
  Tags.limit(Tags.ForkedTestGroup, 2)
)

libraryDependencies += "org.specs2" %% "specs2-core" % "3.7" % Test

scalaVersion := "2.11.7"

inConfig(Test)(Seq(
  fork := true,
  testGrouping := definedTests.value.map { test =>
    new Tests.Group(test.name, Seq(test), Tests.SubProcess(
      ForkOptions(
        javaHome.value,
        outputStrategy.value,
        Nil,
        Some(baseDirectory.value),
        javaOptions.value,
        connectInput.value,
        envVars.value
      )
    ))
  }
))

src/test/scala/example/Test.scala

package example

import org.specs2.mutable.Specification

trait Test extends Specification {
  Thread.sleep(10 * 1000)
}

class Test0 extends Test

class Test1 extends Test

class Test2 extends Test

class Test3 extends Test

---

Then

$ sbt test
...
[info] Passed: Total 0, Failed 0, Errors 0, Passed 0
[success] Total time: 12 s, completed Jul 18, 2016 7:30:10 PM

It should take at least 20 seconds to finish the tests, but ForkedTestGroup doesn't actually limit the number of forked test groups that run at a time.

[pauldraper]

The issue is that the wrong task is being tagged. Workaround:

inConfig(Test)(Seq(
    tags in test += Tags.ForkedTestGroup -> 1,
    tags in testOnly += Tags.ForkedTestGroup -> 1,
    tags in testQuick += Tags.ForkedTestGroup -> 1,
))