From 1432c4874581c8f71ddc420b1297a7e85faffeed Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Mon, 3 Aug 2020 17:36:42 -0700
Subject: [PATCH] fixup! async_hooks: add AsyncResource.bind utility

---
 doc/api/async_hooks.md                   |  6 ++++++
 lib/async_hooks.js                       | 17 ++++++++++++++++-
 test/parallel/test-asyncresource-bind.js | 11 ++++++++++-
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/doc/api/async_hooks.md b/doc/api/async_hooks.md
index 4efeee2f6a00c5..ebab01f6f79ed4 100644
--- a/doc/api/async_hooks.md
+++ b/doc/api/async_hooks.md
@@ -740,6 +740,9 @@ added: REPLACEME
 
 Binds the given function to the current execution context.
 
+The returned function will have an `asyncResource` property referencing
+the `AsyncResource` to which the function is bound.
+
 #### `asyncResource.bind(fn)`
 <!-- YAML
 added: REPLACEME
@@ -749,6 +752,9 @@ added: REPLACEME
 
 Binds the given function to execute to this `AsyncResource`'s scope.
 
+The returned function will have an `asyncResource` property referencing
+the `AsyncResource` to which the function is bound.
+
 #### `asyncResource.runInAsyncScope(fn[, thisArg, ...args])`
 <!-- YAML
 added: v9.6.0
diff --git a/lib/async_hooks.js b/lib/async_hooks.js
index baf0515321afb4..6fa0aa0abadd68 100644
--- a/lib/async_hooks.js
+++ b/lib/async_hooks.js
@@ -2,6 +2,7 @@
 
 const {
   NumberIsSafeInteger,
+  ObjectDefineProperties,
   ReflectApply,
   Symbol,
 } = primordials;
@@ -9,6 +10,7 @@ const {
 const {
   ERR_ASYNC_CALLBACK,
   ERR_ASYNC_TYPE,
+  ERR_INVALID_ARG_TYPE,
   ERR_INVALID_ASYNC_ID
 } = require('internal/errors').codes;
 const { validateString } = require('internal/validators');
@@ -213,7 +215,20 @@ class AsyncResource {
   }
 
   bind(fn) {
-    return this.runInAsyncScope.bind(this, fn);
+    if (typeof fn !== 'function')
+      throw new ERR_INVALID_ARG_TYPE('fn', 'Function', fn);
+    const ret = this.runInAsyncScope.bind(this, fn);
+    ObjectDefineProperties(ret, {
+      'length': {
+        enumerable: true,
+        value: fn.length,
+      },
+      'asyncResource': {
+        enumerable: true,
+        value: this,
+      }
+    });
+    return ret;
   }
 
   static bind(fn, type) {
diff --git a/test/parallel/test-asyncresource-bind.js b/test/parallel/test-asyncresource-bind.js
index f99ff10b8646bd..3aeed475aee126 100644
--- a/test/parallel/test-asyncresource-bind.js
+++ b/test/parallel/test-asyncresource-bind.js
@@ -15,10 +15,19 @@ setImmediate(() => {
 
 const asyncResource = new AsyncResource('test');
 
-const fn2 = asyncResource.bind(() => {
+[1, false, '', {}, []].forEach((i) => {
+  assert.throws(() => asyncResource.bind(i), {
+    code: 'ERR_INVALID_ARG_TYPE'
+  });
+});
+
+const fn2 = asyncResource.bind((a, b) => {
   return executionAsyncId();
 });
 
+assert.strictEqual(fn2.asyncResource, asyncResource);
+assert.strictEqual(fn2.length, 2);
+
 setImmediate(() => {
   const asyncId = executionAsyncId();
   assert.strictEqual(asyncResource.asyncId(), fn2());