From dd1887369505cd172bf20ddd094bec951acdcbc4 Mon Sep 17 00:00:00 2001
From: Joyee Cheung <joyeec9h3@gmail.com>
Date: Tue, 28 Aug 2018 03:57:23 +0800
Subject: [PATCH 1/2] 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.
---
 lib/internal/errors.js                        | 10 ++++++-
 .../test-internal-error-original-names.js     | 30 +++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 test/parallel/test-internal-error-original-names.js

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 6d6bfb7d4db689..998e394dd2051d 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -151,6 +151,8 @@ function makeSystemErrorWithCode(key) {
   };
 }
 
+let useOriginalName = false;
+
 function makeNodeErrorWithCode(Base, key) {
   return class NodeError extends Base {
     constructor(...args) {
@@ -158,6 +160,9 @@ function makeNodeErrorWithCode(Base, key) {
     }
 
     get name() {
+      if (useOriginalName) {
+        return super.name;
+      }
       return `${super.name} [${key}]`;
     }
 
@@ -437,7 +442,10 @@ module.exports = {
   getMessage,
   SystemError,
   codes,
-  E // This is exported only to facilitate testing.
+  // These are exported only to facilitate testing.
+  E,
+  get useOriginalName() { return useOriginalName; },
+  set useOriginalName(value) { useOriginalName = value; }
 };
 
 // To declare an error message, use the E(sym, val, def) function above. The sym
diff --git a/test/parallel/test-internal-error-original-names.js b/test/parallel/test-internal-error-original-names.js
new file mode 100644
index 00000000000000..70ea3e9d402469
--- /dev/null
+++ b/test/parallel/test-internal-error-original-names.js
@@ -0,0 +1,30 @@
+// Flags: --expose-internals
+
+'use strict';
+
+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]');
+}

From 2742d395857d3eed33b643d8830d99703ec96a20 Mon Sep 17 00:00:00 2001
From: Joyee Cheung <joyeec9h3@gmail.com>
Date: Sat, 15 Sep 2018 13:29:31 +0800
Subject: [PATCH 2/2] fixup! errors: add useOriginalName to internal/errors

---
 lib/internal/errors.js                              | 4 +++-
 test/parallel/test-internal-error-original-names.js | 5 +++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 998e394dd2051d..90bc54927f3de0 100644
--- 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
index 70ea3e9d402469..195e39b199cd4c 100644
--- 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');