test,worker: posting undefined/null message to message port

Related: #26122

PR-URL: #26123
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-worker-onmessage.js

@@ -7,13 +7,20 @@ const { Worker, parentPort } = require('worker_threads');
 if (!process.env.HAS_STARTED_WORKER) {
   process.env.HAS_STARTED_WORKER = 1;
   const w = new Worker(__filename);
+  const expectation = [ 4, undefined, null ];
+  const actual = [];
   w.on('message', common.mustCall((message) => {
-    assert.strictEqual(message, 4);
-    w.terminate();
-  }));
+    actual.push(message);
+    if (actual.length === expectation.length) {
+      assert.deepStrictEqual(expectation, actual);
+      w.terminate();
+    }
+  }, expectation.length));
   w.postMessage(2);
 } else {
   parentPort.onmessage = common.mustCall((message) => {
     parentPort.postMessage(message.data * 2);
+    parentPort.postMessage(undefined);
+    parentPort.postMessage(null);
   });
 }