Log reproduction instructions on diff test failure

Author: anatoliykmetyuk

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -225,11 +225,10 @@ trait ParallelTesting extends RunnerOrchestration { self =>
      * Checks if the given actual lines are the same as the ones in the check file.
      * If not, fails the test.
      */
-    final def diffTest(testSource: TestSource, checkFile: JFile, actual: List[String]) = {
+    final def diffTest(testSource: TestSource, checkFile: JFile, actual: List[String], reporters: Seq[TestReporter], logger: LoggedRunnable) = {
       val expected = Source.fromFile(checkFile, "UTF-8").getLines().toList
       for (msg <- diffMessage(testSource.title, actual, expected)) {
-        echo(msg)
-        failTestSource(testSource)
+        onFailure(testSource, reporters, logger, Some(msg))
         dumpOutputToFile(checkFile, actual)
       }
     }
@@ -609,11 +608,11 @@ trait ParallelTesting extends RunnerOrchestration { self =>
       }
     }
 
-    private def verifyOutput(checkFile: Option[JFile], dir: JFile, testSource: TestSource, warnings: Int) = {
+    private def verifyOutput(checkFile: Option[JFile], dir: JFile, testSource: TestSource, warnings: Int, reporters: Seq[TestReporter], logger: LoggedRunnable) = {
       if (Properties.testsNoRun) addNoRunWarning()
       else runMain(testSource.runClassPath) match {        
         case Success(output) => checkFile match {
-          case Some(file) if file.exists => diffTest(testSource, file, output.linesIterator.toList)
+          case Some(file) if file.exists => diffTest(testSource, file, output.linesIterator.toList, reporters, logger)
           case _ =>
         }
         case Failure(output) => 
@@ -627,7 +626,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     }
 
     override def onSuccess(testSource: TestSource, reporters: Seq[TestReporter], logger: LoggedRunnable) =
-      verifyOutput(checkFile(testSource), testSource.outDir, testSource, countWarnings(reporters))
+      verifyOutput(checkFile(testSource), testSource.outDir, testSource, countWarnings(reporters), reporters, logger)
   }
 
   private final class NegTest(testSources: List[TestSource], times: Int, threadLimit: Option[Int], suppressAllOutput: Boolean)(implicit summaryReport: SummaryReporting)
@@ -649,7 +648,7 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     }
 
     override def onSuccess(testSource: TestSource, reporters: Seq[TestReporter], logger: LoggedRunnable): Unit =
-      checkFile(testSource).foreach(diffTest(testSource, _, reporterOutputLines(reporters)))
+      checkFile(testSource).foreach(diffTest(testSource, _, reporterOutputLines(reporters), reporters, logger))
 
     def reporterOutputLines(reporters: Seq[TestReporter]): List[String] =
       reporters.flatMap(_.errors).sortBy(_._1.pos.source.toString).map(_._2).toList