errors: add useOriginalName to internal/errors

This allows us to tell the type of the errors without using
instanceof, which is necessary in WPT harness.

PR-URL: #22556
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>

lib/internal/errors.js

@@ -151,13 +151,18 @@ function makeSystemErrorWithCode(key) {
   };
 }
 
+let useOriginalName = false;
+
 function makeNodeErrorWithCode(Base, key) {
   return class NodeError extends Base {
     constructor(...args) {
       super(getMessage(key, args));
     }
 
     get name() {
+      if (useOriginalName) {
+        return super.name;
+      }
       return `${super.name} [${key}]`;
     }
 
@@ -439,7 +444,12 @@ module.exports = {
   getMessage,
   SystemError,
   codes,
-  E // This is 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; }
 };
 
 // To declare an error message, use the E(sym, val, def) function above. The sym

test/parallel/test-internal-error-original-names.js

@@ -0,0 +1,35 @@
+// Flags: --expose-internals
+
+'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');
+
+
+errors.E('TEST_ERROR_1', 'Error for testing purposes: %s',
+         Error);
+{
+  const err = new errors.codes.TEST_ERROR_1('test');
+  assert(err instanceof Error);
+  assert.strictEqual(err.name, 'Error [TEST_ERROR_1]');
+}
+
+{
+  errors.useOriginalName = true;
+  const err = new errors.codes.TEST_ERROR_1('test');
+  assert(err instanceof Error);
+  assert.strictEqual(err.name, 'Error');
+}
+
+{
+  errors.useOriginalName = false;
+  const err = new errors.codes.TEST_ERROR_1('test');
+  assert(err instanceof Error);
+  assert.strictEqual(err.name, 'Error [TEST_ERROR_1]');
+}