-Yscala-release support: Improve caching artifacts downloaded for tests

Author: prolativ

compiler/test/dotty/Properties.scala

@@ -15,6 +15,11 @@ object Properties {
   val isRunByCI: Boolean = sys.env.isDefinedAt("DOTTY_CI_RUN")
   || sys.env.isDefinedAt("DRONE")  // TODO remove this when we drop Drone
 
+  val testCache: Path =
+    sys.env.get("DOTTY_TEST_CACHE").map(Paths.get(_)).getOrElse {
+      Paths.get(sys.props("user.home"), ".cache", "dotty", "test")
+    }
+
   /** Tests should run interactive? */
   val testsInteractive: Boolean = propIsNullOrTrue("dotty.tests.interactive")
 

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

@@ -1426,14 +1426,15 @@ object ParallelTesting {
         dir
       else
         import scala.sys.process._
-        val zipPath = cache.resolve(s"scala3-$version.tar.gz")
+        val archivePath = cache.resolve(s"scala3-$version.tar.gz")
         val compilerDownloadUrl = s"https://github.com/lampepfl/dotty/releases/download/$version/scala3-$version.tar.gz"
-        (URL(compilerDownloadUrl) #>> zipPath.toFile #&& s"tar -xf $zipPath -C $cache").!!
+        (URL(compilerDownloadUrl) #>> archivePath.toFile #&& s"tar -xf $archivePath -C $cache").!!
+        archivePath.toFile.delete()
         dir
     }
 
   private lazy val cache =
-    val dir = Files.createTempDirectory("dotty.tests")
-    dir.toFile.deleteOnExit()
+    val dir = Properties.testCache.resolve("compilers")
+    dir.toFile.mkdirs()
     dir
 }