fixup! errors: add useOriginalName to internal/errors

joyeecheung · joyeecheung · commit 2742d395857d · 2018-09-15T13:29:31.000+08:00
diff --git a/lib/internal/errors.js b/lib/internal/errors.js
@@ -442,8 +442,10 @@ module.exports = {
   getMessage,
   SystemError,
   codes,
-  // These are exported only to facilitate testing.
+  // This is exported only to facilitate testing.
   E,
+  // This allows us to tell the type of the errors without using
+  // instanceof, which is necessary in WPT harness.
   get useOriginalName() { return useOriginalName; },
   set useOriginalName(value) { useOriginalName = value; }
 };
diff --git a/test/parallel/test-internal-error-original-names.js b/test/parallel/test-internal-error-original-names.js
@@ -2,6 +2,11 @@
 
 'use strict';
 
+// This tests `internal/errors.useOriginalName`
+// This testing feature is needed to allows us to assert the types of
+// errors without using instanceof, which is necessary in WPT harness.
+// Refs: https://github.com/nodejs/node/pull/22556
+
 require('../common');
 const assert = require('assert');
 const errors = require('internal/errors');
