Locate partest-javaagent in classpath

It used to be searched in ./build but that doesn’t work for the sbt
build, where it is actually under ./build-sbt. The correct path is
already on the partest classpath, so we can simply pull it from there
with `findArtifact` instead of using `findJar`.

Some other obsolete uses of `findJar` along with `buildPackLibDir` are
also removed.

Author: szeiger

src/main/scala/scala/tools/partest/nest/FileManager.scala

@@ -111,6 +111,7 @@ class FileManager(val testClassLoader: URLClassLoader) {
   lazy val libraryUnderTest: Path  = findArtifact("library")
   lazy val reflectUnderTest: Path  = findArtifact("reflect")
   lazy val compilerUnderTest: Path = findArtifact("compiler")
+  lazy val agentLib: Path = findArtifact("javaagent")
 
   lazy val testClassPath = testClassLoader.getURLs().map(url => Path(new File(url.toURI))).toList
 
@@ -126,13 +127,14 @@ class FileManager(val testClassLoader: URLClassLoader) {
     else "installed"
   }
 
-  // find library/reflect/compiler jar or subdir under build/$stage/classes/
+  // find library/reflect/compiler/javaagent jar or subdir under build/$stage/classes/
   private def findArtifact(name: String): Path = {
     val canaryClass =
       name match {
-        case "library"  => Class.forName("scala.Unit", false, testClassLoader)
-        case "reflect"  => Class.forName("scala.reflect.api.Symbols", false, testClassLoader)
-        case "compiler" => Class.forName("scala.tools.nsc.Main", false, testClassLoader)
+        case "library"   => Class.forName("scala.Unit", false, testClassLoader)
+        case "reflect"   => Class.forName("scala.reflect.api.Symbols", false, testClassLoader)
+        case "compiler"  => Class.forName("scala.tools.nsc.Main", false, testClassLoader)
+        case "javaagent" => Class.forName("scala.tools.partest.javaagent.ProfilingAgent", false, testClassLoader)
       }
 
     val path = Path(canaryClass.getProtectionDomain.getCodeSource.getLocation.getPath)

src/main/scala/scala/tools/partest/nest/PathSettings.scala

@@ -42,9 +42,6 @@ object PathSettings {
   // Directory <root>/test/files or .../scaladoc
   def srcDir = Directory(testRoot / testSourcePath toCanonical)
 
-  // Directory <root>/build/pack/lib
-  private def buildPackLibDir = Directory(buildDir / "pack" / "lib")
-
   // Directory <root>/test/files/lib
   private def srcLibDir = Directory(srcDir / "lib")
 
@@ -60,8 +57,4 @@ object PathSettings {
 
   def srcSpecLib     = findJar("instrumented", Directory(srcDir / "speclib"))
   def srcCodeLib     = findJar("code",  Directory(srcDir / "codelib"), Directory(testRoot / "files" / "codelib") /* work with --srcpath pending */)
-  def agentLib       = findJar("scala-partest-javaagent", buildPackLibDir)
-  def scalaCheck     = findJar("scalacheck", buildPackLibDir, srcLibDir)
-  def testInterface  = findJar("test-interface", buildPackLibDir, srcLibDir)
-  def diffUtils      = findJar("diffutils", buildPackLibDir)
 }

src/main/scala/scala/tools/partest/nest/Runner.scala

@@ -551,7 +551,7 @@ class Runner(val testFile: File, val suiteRunner: SuiteRunner) {
     case _              => Nil
   }
   def extraJavaOptions = kind match {
-    case "instrumented" => ("-javaagent:"+PathSettings.agentLib.fold(sys.error, identity)).split(' ')
+    case "instrumented" => ("-javaagent:"+agentLib).split(' ')
     case _              => Array.empty[String]
   }