test: increase test-resource-usage.js validation

This commit adds an assertion checking the exact field names
returned by process.resourceUsage(). This ensures that no new
fields accidentally slip into the returned object in the future.

PR-URL: nodejs#28498
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/parallel/test-resource-usage.js

@@ -3,8 +3,7 @@ require('../common');
 const assert = require('assert');
 
 const rusage = process.resourceUsage();
-
-[
+const fields = [
   'userCPUTime',
   'systemCPUTime',
   'maxRSS',
@@ -21,7 +20,11 @@ const rusage = process.resourceUsage();
   'signalsCount',
   'voluntaryContextSwitches',
   'involuntaryContextSwitches'
-].forEach((n) => {
+];
+
+assert.deepStrictEqual(Object.keys(rusage).sort(), fields.sort());
+
+fields.forEach((n) => {
   assert.strictEqual(typeof rusage[n], 'number', `${n} should be a number`);
   assert(rusage[n] >= 0, `${n} should be above or equal 0`);
 });