From 84349ffdba2ede73fca63be71b18ca0762674482 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Szymon=20=C5=81=C4=85giewka?=
 <slagiewka@users.noreply.github.com>
Date: Sat, 10 May 2025 10:39:25 +0200
Subject: [PATCH] refactor(promise-helpers): reuse promise Symbol

Instead of asking the global namespace for it every time, store the
reference and put access it faster each time it's used.
---
 .changeset/cruel-colts-show.md        |  5 +++++
 packages/promise-helpers/src/index.ts | 10 +++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/cruel-colts-show.md

diff --git a/.changeset/cruel-colts-show.md b/.changeset/cruel-colts-show.md
new file mode 100644
index 00000000000..d1c802b7d2b
--- /dev/null
+++ b/.changeset/cruel-colts-show.md
@@ -0,0 +1,5 @@
+---
+'@whatwg-node/promise-helpers': patch
+---
+
+Reuse fake promise Symbol
diff --git a/packages/promise-helpers/src/index.ts b/packages/promise-helpers/src/index.ts
index f6efaa1a896..d70fa1f6b5f 100644
--- a/packages/promise-helpers/src/index.ts
+++ b/packages/promise-helpers/src/index.ts
@@ -1,7 +1,7 @@
 export type MaybePromise<T> = Promise<T> | T;
 export type MaybePromiseLike<T> = PromiseLike<T> | T;
 
-const FAKE_PROMISE_SYMBOL_NAME = '@whatwg-node/promise-helpers/FakePromise';
+const kFakePromise = Symbol.for('@whatwg-node/promise-helpers/FakePromise');
 
 export function isPromise<T>(value: MaybePromise<T>): value is Promise<T>;
 export function isPromise<T>(value: MaybePromiseLike<T>): value is PromiseLike<T>;
@@ -89,7 +89,7 @@ export function fakePromise<T>(value: MaybePromiseLike<T>): Promise<T> {
     },
     [Symbol.toStringTag]: 'Promise',
     __fakePromiseValue: value,
-    [Symbol.for(FAKE_PROMISE_SYMBOL_NAME)]: 'resolved',
+    [kFakePromise]: 'resolved',
   } as Promise<T>;
 }
 
@@ -197,7 +197,7 @@ export function fakeRejectPromise<T>(error: unknown): Promise<T> {
     },
     __fakeRejectError: error,
     [Symbol.toStringTag]: 'Promise',
-    [Symbol.for(FAKE_PROMISE_SYMBOL_NAME)]: 'rejected',
+    [kFakePromise]: 'rejected',
   } as Promise<never>;
 }
 
@@ -315,11 +315,11 @@ function iteratorResult<T>(value: T): IteratorResult<T> {
 }
 
 function isFakePromise<T>(value: any): value is Promise<T> & { __fakePromiseValue: T } {
-  return (value as any)?.[Symbol.for(FAKE_PROMISE_SYMBOL_NAME)] === 'resolved';
+  return (value as any)?.[kFakePromise] === 'resolved';
 }
 
 function isFakeRejectPromise(value: any): value is Promise<never> & { __fakeRejectError: any } {
-  return (value as any)?.[Symbol.for(FAKE_PROMISE_SYMBOL_NAME)] === 'rejected';
+  return (value as any)?.[kFakePromise] === 'rejected';
 }
 
 export function promiseLikeFinally<T>(