Fix #20: test locally built scala.xml classes

not scala-compiler's scala-xml dependency...

also put int a println to show the version we're testing to prevent regression

Author: adriaanm

build.sbt

@@ -17,5 +17,21 @@ libraryDependencies += "junit" % "junit" % "4.11" % "test"
 
 libraryDependencies += "com.novocode" % "junit-interface" % "0.10" % "test"
 
+//// testing:
 // used in CompilerErrors test
-libraryDependencies += "org.scala-lang" % "scala-compiler" % scalaVersion.value % "test"
+libraryDependencies += ("org.scala-lang" % "scala-compiler" % scalaVersion.value % "test").exclude("org.scala-lang.modules", s"scala-xml*")
+
+// needed to fix classloader issues (see #20)
+// alternatively, manage the scala instance as shown below (commented)
+fork in Test := true
+
+// ALTERNATIVE: manage the Scala instance ourselves to exclude the published scala-xml (scala-compiler depends on it)
+// since this dependency hides the classes we're testing
+// managedScalaInstance := false
+//
+// ivyConfigurations    += Configurations.ScalaTool
+//
+// libraryDependencies ++= Seq(
+//    "org.scala-lang" % "scala-library" % scalaVersion.value,
+//    ("org.scala-lang" % "scala-compiler" % scalaVersion.value % "scala-tool").exclude("org.scala-lang.modules", s"scala-xml_${scalaBinaryVersion.value}")
+// )

src/main/scala/scala/xml/XML.scala

@@ -112,3 +112,8 @@ object XML extends XMLLoader[Elem] {
     w.write(Utility.serialize(node, minimizeTags = minimizeTags).toString)
   }
 }
+
+object Properties extends scala.util.PropertiesTrait {
+  protected def propCategory    = "scala-xml"
+  protected def pickJarBasedOn  = classOf[scala.xml.pull.XMLEventReader]
+}

src/test/scala/scala/xml/CompilerErrors.scala

@@ -164,6 +164,11 @@ class CompilerErrors extends CompilerTesting {
 
 // TODO: factor out somewhere?
 class CompilerTesting {
+  // TODO: refine this; for now, just println -- the goal is to ensure we're testing the right version of scala-xml
+  // (it should print the same thing as the version in the sbt build)
+  // we used to always test the scala-xml jar that the compiler depends on, because it was part of the scala-tool ivy config
+  println(s"Testing scala-xml version ${Properties.versionNumberString}.")
+
   def errorMessages(errorSnippet: String, compileOptions: String = "")(code: String): List[String] = {
     import scala.tools.reflect._
     val m  = scala.reflect.runtime.currentMirror