test: improve internal/worker/io.js coverage

PR-URL: nodejs#42387
Refs: https://coverage.nodejs.org/coverage-6d3920d579a3dc3a/lib/internal/worker/io.js.html#L485
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

test/parallel/test-worker-broadcastchannel.js

@@ -7,6 +7,7 @@ const {
   receiveMessageOnPort
 } = require('worker_threads');
 const assert = require('assert');
+const { inspect } = require('util');
 
 assert.throws(() => new BroadcastChannel(Symbol('test')), {
   message: /Cannot convert a Symbol value to a string/
@@ -168,3 +169,17 @@ assert.throws(() => new BroadcastChannel(), {
     });
   });
 }
+
+{
+  const bc = new BroadcastChannel('channel5');
+  assert.strictEqual(
+    inspect(bc.ref()),
+    "BroadcastChannel { name: 'channel5', active: true }"
+  );
+
+  bc.close();
+  assert.strictEqual(
+    inspect(bc.ref()),
+    "BroadcastChannel { name: 'channel5', active: false }"
+  );
+}