.

integration/feature/output-directory/src/OutputDirectoryLockTests.scala

@@ -4,19 +4,27 @@ import mill.testkit.UtestIntegrationTestSuite
 import utest._
 
 import java.io.ByteArrayOutputStream
-import java.util.concurrent.CountDownLatch
+import java.util.concurrent.{CountDownLatch, Executors}
 
-import scala.concurrent.Await
 import scala.concurrent.duration.Duration
+import scala.concurrent.{Await, ExecutionContext, Future}
 
 object OutputDirectoryLockTests extends UtestIntegrationTestSuite {
 
+  private val pool = Executors.newCachedThreadPool()
+  private val ec = ExecutionContext.fromExecutorService(pool)
+
+  override def utestAfterAll(): Unit = {
+    pool.shutdown()
+  }
+
   def tests: Tests = Tests {
     test("basic") - integrationTest { tester =>
       import tester._
       val signalFile = workspacePath / "do-wait"
       System.err.println("Spawning blocking task")
-      val blocksFuture = evalAsync(("show", "blockWhileExists", "--path", signalFile), check = true)
+      val blocksFuture =
+        Future(eval(("show", "blockWhileExists", "--path", signalFile), check = true))(ec)
       while (!os.exists(signalFile) && !blocksFuture.isCompleted)
         Thread.sleep(100L)
       if (os.exists(signalFile))
@@ -43,20 +51,22 @@ object OutputDirectoryLockTests extends UtestIntegrationTestSuite {
       val lock = new CountDownLatch(1)
       val stderr = new ByteArrayOutputStream
       var success = false
-      val futureWaitingRes = evalAsync(
-        testCommand,
-        stderr = os.ProcessOutput {
-          val expectedMessage =
-            "Another Mill process is running tasks, waiting for it to be done..."
-
-          (bytes, len) =>
-            stderr.write(bytes, 0, len)
-            val output = new String(stderr.toByteArray)
-            if (output.contains(expectedMessage))
-              lock.countDown()
-        },
-        check = true
-      )
+      val futureWaitingRes = Future {
+        eval(
+          testCommand,
+          stderr = os.ProcessOutput {
+            val expectedMessage =
+              "Another Mill process is running tasks, waiting for it to be done..."
+
+            (bytes, len) =>
+              stderr.write(bytes, 0, len)
+              val output = new String(stderr.toByteArray)
+              if (output.contains(expectedMessage))
+                lock.countDown()
+          },
+          check = true
+        )
+      }(ec)
       try {
         lock.await()
         success = true

testkit/src/mill/testkit/IntegrationTester.scala

@@ -5,11 +5,6 @@ import mill.eval.Evaluator
 import mill.resolve.SelectMode
 import ujson.Value
 
-import java.util.concurrent.atomic.AtomicInteger
-
-import scala.concurrent.{Future, Promise}
-import scala.util.Try
-
 /**
  * Helper meant for executing Mill integration tests, which runs Mill in a subprocess
  * against a folder with a `build.mill` and project files. Provides APIs such as [[eval]]
@@ -96,49 +91,6 @@ object IntegrationTester {
       )
     }
 
-    private val evalAsyncCounter = new AtomicInteger
-    def evalAsync(
-        cmd: os.Shellable,
-        env: Map[String, String] = millTestSuiteEnv,
-        cwd: os.Path = workspacePath,
-        stdin: os.ProcessInput = os.Pipe,
-        stdout: os.ProcessOutput = os.Pipe,
-        stderr: os.ProcessOutput = os.Pipe,
-        mergeErrIntoOut: Boolean = false,
-        timeout: Long = -1,
-        check: Boolean = false,
-        propagateEnv: Boolean = true,
-        timeoutGracePeriod: Long = 100
-    ): Future[IntegrationTester.EvalResult] = {
-
-      val promise = Promise[IntegrationTester.EvalResult]()
-
-      val thread = new Thread(s"mill-test-background-eval-${evalAsyncCounter.incrementAndGet()}") {
-        setDaemon(true)
-        override def run(): Unit =
-          promise.complete {
-            Try {
-              eval(
-                cmd = cmd,
-                env = env,
-                cwd = cwd,
-                stdin = stdin,
-                stdout = stdout,
-                stderr = stderr,
-                mergeErrIntoOut = mergeErrIntoOut,
-                timeout = timeout,
-                check = check,
-                propagateEnv = propagateEnv,
-                timeoutGracePeriod = timeoutGracePeriod
-              )
-            }
-          }
-      }
-      thread.start()
-
-      promise.future
-    }
-
     def millTestSuiteEnv: Map[String, String] = Map("MILL_TEST_SUITE" -> this.getClass().toString())
 
     /**