test: add regression test for test_runner after hook

Refs: https://github.com/nodejs/node/issues/51997
PR-URL: https://github.com/nodejs/node/pull/51998
Fixes: https://github.com/nodejs/node/issues/51997
Reviewed-By: Matthew Aitken <maitken033380023@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

test/parallel/test-runner-subtest-after-hook.js

@@ -0,0 +1,12 @@
+'use strict';
+const common = require('../common');
+const { test } = require('node:test');
+
+// Regression test for https://github.com/nodejs/node/issues/51997
+test('after hook should be called with no subtests', (t) => {
+  const timer = setTimeout(common.mustNotCall(), 2 ** 30);
+
+  t.after(common.mustCall(() => {
+    clearTimeout(timer);
+  }));
+});