test_runner: avoid waiting on inherited stdio with force exit

lib/internal/test_runner/runner.js

@@ -22,6 +22,7 @@ const {
   SafePromiseAll,
   SafePromiseAllReturnVoid,
   SafePromiseAllSettledReturnVoid,
+  SafePromiseRace,
   SafeSet,
   String,
   StringFromCharCode,
@@ -293,10 +294,15 @@ class FileTest extends Test {
   #rawBufferSize = 0;
   #reportedChildren = 0;
   #pendingPartialV8Header = false;
+  #reportFinished;
+  #resolveReportFinished;
   failedSubtests = false;
 
   constructor(options) {
     super(options);
+    const { promise, resolve } = PromiseWithResolvers();
+    this.#reportFinished = promise;
+    this.#resolveReportFinished = resolve;
     this.loc ??= {
       __proto__: null,
       line: 1,
@@ -306,6 +312,10 @@ class FileTest extends Test {
     this.timeout = null;
   }
 
+  get reportFinished() {
+    return this.#reportFinished;
+  }
+
   willBeFilteredByTags() {
     // File wrappers have no tags of their own. Tag filtering applies to the
     // tests inside the file, which run in a child process (or in-process
@@ -518,6 +528,9 @@ class FileTest extends Test {
 
       deserializer.readHeader();
       const item = deserializer.readValue();
+      if (item.type === 'test:summary') {
+        this.#resolveReportFinished();
+      }
       this.addToReport(item);
     }
   }
@@ -592,9 +605,17 @@ function runTestFile(path, filesWatcher, opts) {
         });
       });
 
+      const stdoutFinished = finished(
+        child.stdout,
+        { __proto__: null, signal: t.signal },
+      );
+      const reportFinished = opts.forceExit ?
+        SafePromiseRace([stdoutFinished, subtest.reportFinished]) :
+        stdoutFinished;
+
       const { 0: { 0: code, 1: signal } } = await SafePromiseAll([
         once(child, 'exit', { __proto__: null, signal: t.signal }),
-        finished(child.stdout, { __proto__: null, signal: t.signal }),
+        reportFinished,
       ]);
 
       // Close readline interface to prevent memory leak

test/fixtures/test-runner/force-exit-inherited-stdio.js

@@ -0,0 +1,15 @@
+'use strict';
+
+const { spawn } = require('node:child_process');
+const { test } = require('node:test');
+
+test('leaks a child with inherited stdio', () => {
+  spawn(
+    process.execPath,
+    [
+      '-e',
+      `setTimeout(() => {}, ${process.env.TEST_RUNNER_STALL_MS})`,
+    ],
+    { stdio: 'inherit' },
+  );
+});

test/parallel/test-runner-force-exit-inherited-stdio.js

@@ -0,0 +1,41 @@
+'use strict';
+
+const common = require('../common');
+
+const assert = require('node:assert');
+const { spawnSync } = require('node:child_process');
+const fixtures = require('../common/fixtures');
+
+const fixture =
+  fixtures.path('test-runner/force-exit-inherited-stdio.js');
+
+const maxDuration = common.platformTimeout(2000);
+const stallDuration = common.platformTimeout(4000);
+const start = Date.now();
+
+const result = spawnSync(
+  process.execPath,
+  [
+    '--test',
+    '--test-force-exit',
+    fixture,
+  ],
+  {
+    encoding: 'utf8',
+    env: {
+      ...process.env,
+      TEST_RUNNER_STALL_MS: String(stallDuration),
+    },
+  },
+);
+
+const duration = Date.now() - start;
+
+assert.strictEqual(result.status, 0);
+assert.strictEqual(result.signal, null);
+assert.strictEqual(result.stderr, '');
+
+assert.ok(
+  duration < maxDuration,
+  `test runner took ${duration}ms to exit`,
+);