Allow running long tests with testOnly

Improves #3194

Author: nicolasstucki

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -5,6 +5,7 @@ package dotc
 import org.junit.{ Test, BeforeClass, AfterClass }
 import org.junit.Assert._
 import org.junit.Assume._
+import org.junit.experimental.categories.Category
 
 import java.nio.file._
 import java.util.stream.{ Stream => JStream }
@@ -295,8 +296,8 @@ class CompilationTests extends ParallelTesting {
     tests.foreach(_.delete())
   }
 
+  @Category(Array(classOf[SlowTests]))
   @Test def testOptimised: Unit = {
-    assumeTrue("Only executes on Drone", dotty.Properties.isRunByDrone)
     val outputDir = defaultOutputDir + "optimised/"
     compileFilesInDir("../tests/pos", defaultOptimised, outputDir).checkCompile()
     compileFilesInDir("../tests/run", defaultOptimised, outputDir).checkRuns()

compiler/test/dotty/tools/dotc/IdempotencyTests.scala

@@ -7,6 +7,7 @@ import java.nio.file.{Files, Path, Paths}
 
 import org.junit.Assume.assumeTrue
 import org.junit.{AfterClass, Test}
+import org.junit.experimental.categories.Category
 
 import scala.concurrent.duration._
 import vulpix.{ParallelTesting, SummaryReport, SummaryReporting, TestConfiguration}
@@ -24,9 +25,8 @@ class IdempotencyTests extends ParallelTesting {
   def isInteractive = SummaryReport.isInteractive
   def testFilter = Properties.testsFilter
 
-  /* TODO: Only run them selectively? */
+  @Category(Array(classOf[SlowTests]))
   @Test def idempotency: Unit = {
-    assumeTrue("Only executes on Drone", dotty.Properties.isRunByDrone)
 
     val opt = defaultOptions.and("-YemitTasty")
 

compiler/test/dotty/tools/dotc/SlowTests.scala

@@ -0,0 +1,4 @@
+package dotty.tools.dotc
+
+/** SlowTest category for JUnit */
+trait SlowTests

project/Build.scala

@@ -465,13 +465,13 @@ object Build {
 
       test in Test := {
         // Exclude legacy tests by default
-        (testOnly in Test).toTask(" -- --exclude-categories=java.lang.Exception").value
+        (testOnly in Test).toTask(" -- --exclude-categories=java.lang.Exception,dotty.tools.dotc.SlowTests").value
       },
 
       vulpix := Def.inputTaskDyn {
         val args: Seq[String] = spaceDelimited("<arg>").parsed
-        val cmd = " dotty.tools.dotc.CompilationTests" + {
-          if (args.nonEmpty) " -- -Ddotty.tests.filter=" + args.mkString(" ")
+        val cmd = " dotty.tools.dotc.CompilationTests -- --exclude-categories=dotty.tools.dotc.SlowTests" + {
+          if (args.nonEmpty) " -Ddotty.tests.filter=" + args.mkString(" ")
           else ""
         }
         (testOnly in Test).toTask(cmd)