partest: put more stuff on javac classpath

Some java tests require the scala-library to be present on the
classpath, this fixes tests/pos/java-interop/{t1186, t1235, t1254,
t1642}.
Also correctly redirect the output of javac so that it will be displayed
by partest --verbose

Author: smarter

test/dotty/partest/DPConsoleRunner.scala

@@ -134,6 +134,62 @@ class DPTestRunner(testFile: File, suiteRunner: DPSuiteRunner) extends nest.Runn
   // override to provide DottyCompiler
   override def newCompiler = new dotty.partest.DPDirectCompiler(this)
 
+  // Adapted from nest.Runner#javac because:
+  // - Our classpath handling is different and we need to pass extraClassPath
+  //   to java to get the scala-library which is required for some java tests
+  // - The compiler output should be redirected to cLogFile, like the output of
+  //   dotty itself
+  override def javac(files: List[File]): TestState = {
+    import fileManager._
+    import suiteRunner._
+    import FileManager.joinPaths
+    // compile using command-line javac compiler
+    val args = Seq(
+      javacCmdPath,
+      "-d",
+      outDir.getAbsolutePath,
+      "-classpath",
+      joinPaths(outDir :: extraClasspath ++ testClassPath)
+    ) ++ files.map(_.getAbsolutePath)
+
+    pushTranscript(args mkString " ")
+
+    val captured = StreamCapture(runCommand(args, cLogFile))
+    if (captured.result) genPass() else {
+      cLogFile appendAll captured.stderr
+      cLogFile appendAll captured.stdout
+      genFail("java compilation failed")
+    }
+  }
+
+  // FIXME: This is copy-pasted from nest.Runner where it is private
+  // Remove this once https://github.com/scala/scala-partest/pull/61 is merged
+  /** Runs command redirecting standard out and
+   *  error out to output file.
+   */
+  def runCommand(args: Seq[String], outFile: File): Boolean = {
+    import scala.sys.process.{ Process, ProcessLogger }
+    //(Process(args) #> outFile !) == 0 or (Process(args) ! pl) == 0
+    val pl = ProcessLogger(outFile)
+    val nonzero = 17     // rounding down from 17.3
+    def run: Int = {
+      val p = Process(args) run pl
+      try p.exitValue
+      catch {
+        case e: InterruptedException =>
+          NestUI verbose s"Interrupted waiting for command to finish (${args mkString " "})"
+          p.destroy
+          nonzero
+        case t: Throwable =>
+          NestUI verbose s"Exception waiting for command to finish: $t (${args mkString " "})"
+          p.destroy
+          throw t
+      }
+      finally pl.close()
+    }
+    (pl buffer run) == 0
+  }
+
   // override to provide default dotty flags from file in directory
   override def flagsForCompilation(sources: List[File]): List[String] = {
     val specificFlags = super.flagsForCompilation(sources)