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refactor(promise-helpers): reuse promise Symbol #2408

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Merged
merged 1 commit into from
May 10, 2025
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refactor(promise-helpers): reuse promise Symbol #2408

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5 changes: 5 additions & 0 deletions .changeset/cruel-colts-show.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@whatwg-node/promise-helpers': patch
---

Reuse fake promise Symbol
10 changes: 5 additions & 5 deletions packages/promise-helpers/src/index.ts
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Original file line number Diff line number Diff line change
@@ -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>;
Expand Down Expand Up @@ -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>;
}

Expand Down Expand Up @@ -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>;
}

Expand Down Expand Up @@ -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>(
Expand Down