Print done message from test framework to stdout

build.sc

@@ -397,6 +397,7 @@ trait MillBaseTestsModule extends MillJavaModule with TestModule {
       s"-DTEST_SCALANATIVE_VERSION=${Deps.Scalanative_0_4.scalanativeVersion}",
       s"-DTEST_UTEST_VERSION=${Deps.utest.dep.version}",
       s"-DTEST_SCALATEST_VERSION=${Deps.TestDeps.scalaTest.dep.version}",
+      s"-DTEST_TEST_INTERFACE_VERSION=${Deps.sbtTestInterface.dep.version}",
       s"-DTEST_ZIOTEST_VERSION=${Deps.TestDeps.zioTest.dep.version}",
       s"-DTEST_ZINC_VERSION=${Deps.zinc.dep.version}"
     )

scalalib/test/resources/testrunner/doneMessageFailure/src/DoneMessageFailureFramework.scala

@@ -0,0 +1,42 @@
+package mill.scalalib
+
+import sbt.testing._
+
+class DoneMessageFailureFramework extends Framework {
+  def fingerprints() = Array.empty
+  def name() = "DoneMessageFailureFramework"
+  def runner(
+      args: Array[String],
+      remoteArgs: Array[String],
+      testClassLoader: ClassLoader
+  ): Runner = new Runner {
+    def args() = Array.empty
+    def done() = "test failure done message"
+    def remoteArgs() = Array.empty
+    def tasks(taskDefs: Array[TaskDef]) = Array(new Task {
+      def taskDef(): TaskDef = null
+      def execute(
+          eventHandler: EventHandler,
+          loggers: Array[Logger]
+      ): Array[Task] = {
+        eventHandler.handle(new Event {
+
+          override def fullyQualifiedName(): String = "foo.bar"
+
+          override def fingerprint(): Fingerprint = new Fingerprint {}
+
+          override def selector(): Selector = new TestSelector("foo.bar")
+
+          override def status(): Status = Status.Failure
+
+          override def throwable(): OptionalThrowable = new OptionalThrowable()
+
+          override def duration(): Long = 0L
+
+        })
+        Array.empty
+      }
+      def tags = Array.empty
+    })
+  }
+}

scalalib/test/resources/testrunner/doneMessageNull/src/DoneMessageNullFramework.scala

@@ -0,0 +1,18 @@
+package mill.scalalib
+
+import sbt.testing._
+
+class DoneMessageNullFramework extends Framework {
+  def fingerprints() = Array.empty
+  def name() = "DoneMessageNullFramework"
+  def runner(
+      args: Array[String],
+      remoteArgs: Array[String],
+      testClassLoader: ClassLoader
+  ): Runner = new Runner {
+    def args() = Array.empty
+    def done() = null
+    def remoteArgs() = Array.empty
+    def tasks(taskDefs: Array[TaskDef]) = Array.empty
+  }
+}

scalalib/test/resources/testrunner/doneMessageSuccess/src/DoneMessageSuccessFramework.scala

@@ -0,0 +1,18 @@
+package mill.scalalib
+
+import sbt.testing._
+
+class DoneMessageSuccessFramework extends Framework {
+  def fingerprints() = Array.empty
+  def name() = "DoneMessageSuccessFramework"
+  def runner(
+      args: Array[String],
+      remoteArgs: Array[String],
+      testClassLoader: ClassLoader
+  ): Runner = new Runner {
+    def args() = Array.empty
+    def done() = "test success done message"
+    def remoteArgs() = Array.empty
+    def tasks(taskDefs: Array[TaskDef]) = Array.empty
+  }
+}

scalalib/test/src/mill/scalalib/TestRunnerTests.scala

@@ -2,10 +2,13 @@ package mill.scalalib
 
 import mill.{Agg, T}
 
+import mill.api.Result
 import mill.util.{TestEvaluator, TestUtil}
 import utest._
 import utest.framework.TestPath
 
+import java.io.{ByteArrayOutputStream, PrintStream}
+
 object TestRunnerTests extends TestSuite {
   object testrunner extends TestUtil.BaseModule with ScalaModule {
     override def millSourcePath = TestUtil.getSrcPathBase() / millOuterCtx.enclosing.split('.')
@@ -28,6 +31,23 @@ object TestRunnerTests extends TestSuite {
       }
     }
 
+    trait DoneMessage extends ScalaTests {
+      override def ivyDeps = T {
+        super.ivyDeps() ++ Agg(
+          ivy"org.scala-sbt:test-interface:${sys.props.getOrElse("TEST_TEST_INTERFACE_VERSION", ???)}"
+        )
+      }
+    }
+    object doneMessageSuccess extends DoneMessage {
+      def testFramework = "mill.scalalib.DoneMessageSuccessFramework"
+    }
+    object doneMessageFailure extends DoneMessage {
+      def testFramework = "mill.scalalib.DoneMessageFailureFramework"
+    }
+    object doneMessageNull extends DoneMessage {
+      def testFramework = "mill.scalalib.DoneMessageNullFramework"
+    }
+
     object ziotest extends ScalaTests with TestModule.ZioTest {
       override def ivyDeps = T {
         super.ivyDeps() ++ Agg(
@@ -42,11 +62,12 @@ object TestRunnerTests extends TestSuite {
 
   def workspaceTest[T](
       m: TestUtil.BaseModule,
+      outStream: PrintStream = System.out,
       resourcePath: os.Path = resourcePath
   )(t: TestEvaluator => T)(
       implicit tp: TestPath
   ): T = {
-    val eval = new TestEvaluator(m)
+    val eval = new TestEvaluator(m, outStream = outStream)
     os.remove.all(m.millSourcePath)
     os.remove.all(eval.outPath)
     os.makeDir.all(m.millSourcePath / os.up)
@@ -88,6 +109,29 @@ object TestRunnerTests extends TestSuite {
         }
       }
 
+      "doneMessage" - {
+        test("failure") {
+          val outStream = new ByteArrayOutputStream()
+          workspaceTest(testrunner, outStream = new PrintStream(outStream, true)) { eval =>
+            val Left(Result.Failure(msg, _)) = eval(testrunner.doneMessageFailure.test())
+            val stdout = new String(outStream.toByteArray)
+            assert(stdout.contains("test failure done message"))
+          }
+        }
+        test("success") {
+          val outStream = new ByteArrayOutputStream()
+          workspaceTest(testrunner, outStream = new PrintStream(outStream, true)) { eval =>
+            val Right(_) = eval(testrunner.doneMessageSuccess.test())
+            val stdout = new String(outStream.toByteArray)
+            assert(stdout.contains("test success done message"))
+          }
+        }
+        test("null") {
+          workspaceTest(testrunner) { eval =>
+            val Right(_) = eval(testrunner.doneMessageNull.test())
+          }
+        }
+      }
       "ScalaTest" - {
         test("scalatest.test") {
           workspaceTest(testrunner) { eval =>

testrunner/src/mill/testrunner/TestRunnerUtils.scala

@@ -156,6 +156,13 @@ import scala.jdk.CollectionConverters.IteratorHasAsScala
       runner.done()
     }
 
+    if (doneMessage != null && doneMessage.nonEmpty) {
+      if (doneMessage.endsWith("\n"))
+        ctx.log.outputStream.print(doneMessage)
+      else
+        ctx.log.outputStream.println(doneMessage)
+    }
+
     val results = for (e <- events.iterator().asScala) yield {
       val ex =
         if (e.throwable().isDefined) Some(e.throwable().get) else None