test: test undefined in util

PR-URL: #22741
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

test/parallel/test-util.js

@@ -113,14 +113,17 @@ assert.strictEqual(util.isBoolean(false), true);
 assert.strictEqual(util.isBoolean('string'), false);
 
 assert.strictEqual(util.isNull(null), true);
+assert.strictEqual(util.isNull(undefined), false);
 assert.strictEqual(util.isNull(), false);
 assert.strictEqual(util.isNull('string'), false);
 
+assert.strictEqual(util.isUndefined(undefined), true);
 assert.strictEqual(util.isUndefined(), true);
 assert.strictEqual(util.isUndefined(null), false);
 assert.strictEqual(util.isUndefined('string'), false);
 
 assert.strictEqual(util.isNullOrUndefined(null), true);
+assert.strictEqual(util.isNullOrUndefined(undefined), true);
 assert.strictEqual(util.isNullOrUndefined(), true);
 assert.strictEqual(util.isNullOrUndefined('string'), false);