"play test" classpath differs from "sbt test" classpath - junit

Question

Situation:
I want to execute JUnit test cases for my Play! 2.0 application on a Jenkins Server.
To build and test my app on the server I want to use SBT (with command sequence: clean compile test).
Problem:
Regardless of Jenkins, the command play test uses a different classpath than the command java -jar "sbt-launch.jar" test (both commands executed in the root directory of my play project, both commands use the same sbt version 0.12.2). My test cases can be compiled with play test but with java -jar "sbt-launch.jar" test the compiler complains that some JUnit classes (e.g., org.junit.rules.TestWatcher) are missing.
Analysis:
The command show test:full-classpath reveals that the classpathes indeed differ:
play test classpath contains: Attributed(<playhome>\repository\local\junit\junit-dep\4.10\jars\junit-dep.jar)
java -jar "sbt-launch.jar test classpath contains: Attributed(<userhome>\.ivy2\cache\junit\junit-dep\jars\junit-dep-4.8.2.jar)
Question:
Any ideas how to ensure that java -jar "sbt-launch.jar test uses the same classpath as play test?
Build.scala:
import sbt._
import Keys._
import play.Project._
object ApplicationBuild extends Build {
val appName = "my app"
val appVersion = "1.0-SNAPSHOT"
val appDependencies = Seq(
// Play framework dependencies
javaCore, javaJdbc, javaEbean,
// Add your project dependencies here
"com.typesafe" %% "play-plugins-mailer" % "2.1.0",
"com.feth" %% "play-authenticate" % "0.2.5-SNAPSHOT",
"org.mongodb" % "mongo-java-driver" % "2.10.1",
"com.embedly" % "embedly-api" % "0.1.5",
"org.mockito" % "mockito-all" % "1.9.5",
"org.mongojack" % "mongojack" % "2.0.0-RC5",
"commons-io" % "commons-io" % "2.3"
)
val main = play.Project(appName, appVersion, appDependencies).settings(
resolvers += Resolver.url("play-easymail (release)", url("http://joscha.github.com/play-easymail/repo/releases/"))(Resolver.ivyStylePatterns),
resolvers += Resolver.url("play-easymail (snapshot)", url("http://joscha.github.com/play-easymail/repo/snapshots/"))(Resolver.ivyStylePatterns),
resolvers += Resolver.url("play-authenticate (release)", url("http://joscha.github.com/play-authenticate/repo/releases/"))(Resolver.ivyStylePatterns),
resolvers += Resolver.url("play-authenticate (snapshot)", url("http://joscha.github.com/play-authenticate/repo/snapshots/"))(Resolver.ivyStylePatterns)
)
}

Answer 1

The play script rewires sbt to use a local JUnit file repository in addition to any remote you've used. This is why the download is so large. Ivy, by default, will not copy local files into its local cache, as it assumes they are stable.
SO, what you're seeing is the sbt script which downloaded the file vs. the Play script which has its own local repo that takes priority over the downloaded file.
Now the fun part is around versioning. Ivy has interesting version conflict resolution.
If you paste you look in your target/resolution-cache/reports directory, you may get some insight into the difference between the two commands and why the one junit is chosen over another. My guess is there's a dynamic version range which is looking in the local repository for the play script and not finding the newer version of junit-dep.