Integrate scala-partest-interface for sbt into scala-partest

It’s only a few lines of code, it ends up on the same ClassLoader in
the Scala build, and we already have a dependency on sbt’s
test-interface here anyway.

The test framework class name changes from
`scala.tools.partest.Framework` to `scala.tools.partest.sbt.Framework`.

Author: szeiger

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

@@ -9,15 +9,7 @@
 package scala.tools.partest
 package nest
 
-import sbt.testing.EventHandler
-import sbt.testing.Logger
-import sbt.testing.Event
-import sbt.testing.Fingerprint
-import sbt.testing.Selector
-import sbt.testing.Status
-import sbt.testing.OptionalThrowable
-import sbt.testing.SuiteSelector
-import sbt.testing.TestSelector
+import _root_.sbt.testing._
 import java.net.URLClassLoader
 import TestState._
 

src/main/scala/scala/tools/partest/sbt/Framework.scala

@@ -0,0 +1,70 @@
+package scala.tools.partest.sbt
+
+import scala.language.reflectiveCalls
+
+import _root_.sbt.testing._
+import java.net.URLClassLoader
+import java.io.File
+
+object Framework {
+  // as partest is not driven by test classes discovered by sbt, need to add this marker fingerprint to definedTests
+  val fingerprint = new AnnotatedFingerprint { def isModule = true; def annotationName = "partest" }
+
+  // TODO how can we export `fingerprint` so that a user can just add this to their build.sbt
+  // definedTests in Test += new sbt.TestDefinition("partest", fingerprint, true, Array())
+}
+class Framework extends sbt.testing.Framework {
+  def fingerprints: Array[Fingerprint] = Array(Framework.fingerprint)
+  def name: String = "partest"
+
+  def runner(args: Array[String], remoteArgs: Array[String], testClassLoader: ClassLoader): sbt.testing.Runner =
+    new Runner(args, remoteArgs, testClassLoader)
+}
+
+/** Represents one run of a suite of tests.
+  */
+case class Runner(args: Array[String], remoteArgs: Array[String], testClassLoader: ClassLoader) extends sbt.testing.Runner {
+
+  def tasks(taskDefs: Array[TaskDef]): Array[sbt.testing.Task] = taskDefs map (SbtPartestTask(_, args): sbt.testing.Task)
+
+  /** Indicates the client is done with this <code>Runner</code> instance.
+    *
+    *  @return a possibly multi-line summary string, or the empty string if no summary is provided -- TODO
+    */
+  def done(): String = ""
+}
+
+/** Run partest in this VM. Assumes we're running in a forked VM!
+  */
+case class SbtPartestTask(taskDef: TaskDef, args: Array[String]) extends Task {
+  /** Executes this task, possibly returning to the client new tasks to execute. */
+  def execute(eventHandler: EventHandler, loggers: Array[Logger]): Array[Task] = {
+    val forkedCp    = scala.util.Properties.javaClassPath
+    val classLoader = new URLClassLoader(forkedCp.split(java.io.File.pathSeparator).map(new File(_).toURI.toURL))
+    val runner      = SBTRunner(Framework.fingerprint, eventHandler, loggers, "files", classLoader, null, null, Array.empty[String], args)
+
+    if (Runtime.getRuntime().maxMemory() / (1024*1024) < 800)
+      loggers foreach (_.warn(s"""Low heap size detected (~ ${Runtime.getRuntime().maxMemory() / (1024*1024)}M). Please add the following to your build.sbt: javaOptions in Test += "-Xmx1G""""))
+
+    try runner.run
+    catch {
+      case ex: ClassNotFoundException =>
+        loggers foreach { l => l.error("Please make sure partest is running in a forked VM by including the following line in build.sbt:\nfork in Test := true") }
+        throw ex
+    }
+
+    Array()
+  }
+
+  type SBTRunner = { def run(): Unit }
+
+  // use reflection to instantiate scala.tools.partest.nest.SBTRunner,
+  // casting to the structural type SBTRunner above so that method calls on the result will be invoked reflectively as well
+  private def SBTRunner(partestFingerprint: Fingerprint, eventHandler: EventHandler, loggers: Array[Logger], srcDir: String, testClassLoader: URLClassLoader, javaCmd: File, javacCmd: File, scalacArgs: Array[String], args: Array[String]): SBTRunner = {
+    val runnerClass = Class.forName("scala.tools.partest.nest.SBTRunner")
+    runnerClass.getConstructors()(0).newInstance(partestFingerprint, eventHandler, loggers, srcDir, testClassLoader, javaCmd, javacCmd, scalacArgs, args).asInstanceOf[SBTRunner]
+  }
+
+  /** A possibly zero-length array of string tags associated with this task. */
+  def tags: Array[String] = Array()
+}