Add a way filter FromTasty tests

In sbt use: `testFromTasty XYZ`

It does the same as `testCompilation XYZ` but on the tasty tests

Author: nicolasstucki

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

@@ -1267,26 +1267,33 @@ trait ParallelTesting extends RunnerOrchestration { self =>
 
     val (dirs, files) = compilationTargets(sourceDir, blacklist)
 
-    val targets =
-      files.map { f =>
-        val classpath = createOutputDirsForFile(f, sourceDir, outDir)
-        JointCompilationSource(testGroup.name, Array(f), flags.withClasspath(classpath.getPath), classpath, fromTasty = true)
-      }
+    val filteredFiles = testFilter match {
+      case Some(str) => files.filter(_.getAbsolutePath.contains(str))
+      case None => files
+    }
+
+    val targets = filteredFiles.map { f =>
+      val classpath = createOutputDirsForFile(f, sourceDir, outDir)
+      JointCompilationSource(testGroup.name, Array(f), flags.withClasspath(classpath.getPath), classpath, fromTasty = true)
+    }
     // TODO add SeparateCompilationSource from tasty?
 
     val targets2 =
-      files
+      filteredFiles
         .filter(f => dotty.tools.io.File(f.toPath).changeExtension("decompiled").exists)
         .map { f =>
-        val classpath = createOutputDirsForFile(f, sourceDir, outDir)
-        JointCompilationSource(testGroup.name, Array(f), flags.withClasspath(classpath.getPath), classpath, decompilation = true)
-      }
+          val classpath = createOutputDirsForFile(f, sourceDir, outDir)
+          JointCompilationSource(testGroup.name, Array(f), flags.withClasspath(classpath.getPath), classpath, decompilation = true)
+        }
 
     // Create a CompilationTest and let the user decide whether to execute a pos or a neg test
     val generateClassFiles = compileFilesInDir(f, flags0, blacklist)
 
     val decompilationDir = outDir + sourceDir.getName + "_decompiled"
 
+    if (targets2.isEmpty)
+      new JFile(decompilationDir).mkdirs()
+
     new TastyCompilationTest(
       generateClassFiles.keepOutput,
       new CompilationTest(targets).keepOutput,

project/Build.scala

@@ -65,6 +65,9 @@ object Build {
   // Run tests with filter through vulpix test suite
   lazy val testCompilation = inputKey[Unit]("runs integration test with the supplied filter")
 
+  // Run TASTY tests with filter through vulpix test suite
+  lazy val testFromTasty = inputKey[Unit]("runs tasty integration test with the supplied filter")
+
   // Spawns a repl with the correct classpath
   lazy val repl = inputKey[Unit]("run the REPL with correct classpath")
 
@@ -583,6 +586,15 @@ object Build {
         (testOnly in Test).toTask(cmd)
       }.evaluated,
 
+      testFromTasty := Def.inputTaskDyn {
+        val args: Seq[String] = spaceDelimited("<arg>").parsed
+        val cmd = " dotty.tools.dotc.FromTastyTests -- " + {
+          if (args.nonEmpty) " -Ddotty.tests.filter=" + args.mkString(" ")
+          else ""
+        }
+        (testOnly in Test).toTask(cmd)
+      }.evaluated,
+
       dotr := {
         val args: List[String] = spaceDelimited("<arg>").parsed.toList
         val attList = (dependencyClasspath in Runtime).value