test: add regression test for C++-created Buffer transfer

Add a test for a regression that occurs when transferring some
`Buffer` objects that were created from C++ to a parent thread.

Fixes: #34126

PR-URL: #34140
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>

Author: addaleax

test/parallel/test-worker-crypto-sign-transfer-result.js

@@ -0,0 +1,30 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+const fixturesPath = require.resolve('../common/fixtures');
+
+// Test that transferring the result of e.g. crypto.sign() from Worker to parent
+// thread does not crash
+
+const w = new Worker(`
+const { parentPort } = require('worker_threads');
+const crypto = require('crypto');
+const assert = require('assert');
+const fixtures = require(${JSON.stringify(fixturesPath)});
+
+const keyPem = fixtures.readKey('rsa_private.pem');
+
+const buf = crypto.sign('sha256', Buffer.from('hello'), keyPem);
+assert.notStrictEqual(buf.byteLength, 0);
+parentPort.postMessage(buf, [buf.buffer]);
+assert.strictEqual(buf.byteLength, 0);
+`, { eval: true });
+
+w.on('message', common.mustCall((buf) => {
+  assert.notStrictEqual(buf.byteLength, 0);
+}));
+w.on('exit', common.mustCall());