From a415d0375afa4c3726174d8f87db340ca20a428c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tim=20Wei=C3=9Fenfels?=
 <10491533+tim-we@users.noreply.github.com>
Date: Wed, 12 Nov 2025 18:38:19 +0100
Subject: [PATCH] feat(expect): add Set support to toBeOneOf (#8906)

Co-authored-by: Vladimir <sleuths.slews0s@icloud.com>
---
 docs/api/expect.md                     |  8 ++++++--
 packages/expect/src/custom-matchers.ts | 22 ++++++++++++++--------
 packages/expect/src/types.ts           |  4 ++--
 test/core/test/jest-expect.test.ts     |  6 ++++++
 4 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/docs/api/expect.md b/docs/api/expect.md
index f7237002a..c5a0a290d 100644
--- a/docs/api/expect.md
+++ b/docs/api/expect.md
@@ -379,9 +379,13 @@ test('getApplesCount has some unusual side effects...', () => {
 
 ## toBeOneOf
 
-- **Type:** `(sample: Array<any>) => any`
+- **Type:** `(sample: Array<any> | Set<any>) => any`
 
-`toBeOneOf` asserts if a value matches any of the values in the provided array.
+`toBeOneOf` asserts if a value matches any of the values in the provided array or set.
+
+::: warning EXPERIMENTAL
+Providing a `Set` is an experimental feature and may change in a future release.
+:::
 
 ```ts
 import { expect, test } from 'vitest'
diff --git a/packages/expect/src/custom-matchers.ts b/packages/expect/src/custom-matchers.ts
index 18ede7c46..5eaf5366e 100644
--- a/packages/expect/src/custom-matchers.ts
+++ b/packages/expect/src/custom-matchers.ts
@@ -27,21 +27,27 @@ ${printReceived(actual)}`,
     }
   },
 
-  toBeOneOf(actual: unknown, expected: Array<unknown>) {
+  toBeOneOf(actual: unknown, expected: Array<unknown> | Set<unknown>) {
     const { equals, customTesters } = this
     const { printReceived, printExpected, matcherHint } = this.utils
 
-    if (!Array.isArray(expected)) {
+    let pass: boolean
+
+    if (Array.isArray(expected)) {
+      pass = expected.length === 0
+        || expected.some(item =>
+          equals(item, actual, customTesters),
+        )
+    }
+    else if (expected instanceof Set) {
+      pass = expected.size === 0 || expected.has(actual) || [...expected].some(item => equals(item, actual, customTesters))
+    }
+    else {
       throw new TypeError(
-        `You must provide an array to ${matcherHint('.toBeOneOf')}, not '${typeof expected}'.`,
+        `You must provide an array or set to ${matcherHint('.toBeOneOf')}, not '${typeof expected}'.`,
       )
     }
 
-    const pass = expected.length === 0
-      || expected.some(item =>
-        equals(item, actual, customTesters),
-      )
-
     return {
       pass,
       message: () =>
diff --git a/packages/expect/src/types.ts b/packages/expect/src/types.ts
index ef004ed76..ae0954015 100644
--- a/packages/expect/src/types.ts
+++ b/packages/expect/src/types.ts
@@ -129,14 +129,14 @@ interface CustomMatcher {
   toSatisfy: (matcher: (value: any) => boolean, message?: string) => any
 
   /**
-   * Matches if the received value is one of the values in the expected array.
+   * Matches if the received value is one of the values in the expected array or set.
    *
    * @example
    * expect(1).toBeOneOf([1, 2, 3])
    * expect('foo').toBeOneOf([expect.any(String)])
    * expect({ a: 1 }).toEqual({ a: expect.toBeOneOf(['1', '2', '3']) })
    */
-  toBeOneOf: <T>(sample: Array<T>) => any
+  toBeOneOf: <T>(sample: Array<T> | Set<T>) => any
 }
 
 export interface AsymmetricMatchersContaining extends CustomMatcher {
diff --git a/test/core/test/jest-expect.test.ts b/test/core/test/jest-expect.test.ts
index dba00dd27..8e3a2c9d9 100644
--- a/test/core/test/jest-expect.test.ts
+++ b/test/core/test/jest-expect.test.ts
@@ -636,7 +636,9 @@ describe('toBeOneOf()', () => {
     expect(0).toBeOneOf([0, 1, 2])
     expect(0).toBeOneOf([expect.any(Number)])
     expect('apple').toBeOneOf(['apple', 'banana', 'orange'])
+    expect('apple').toBeOneOf(new Set(['apple', 'banana', 'orange']))
     expect('apple').toBeOneOf([expect.any(String)])
+    expect('apple').toBeOneOf(new Set([expect.any(String)]))
     expect(true).toBeOneOf([true, false])
     expect(true).toBeOneOf([expect.any(Boolean)])
     expect(null).toBeOneOf([expect.any(Object)])
@@ -647,7 +649,9 @@ describe('toBeOneOf()', () => {
     expect(3).not.toBeOneOf([0, 1, 2])
     expect(3).not.toBeOneOf([expect.any(String)])
     expect('mango').not.toBeOneOf(['apple', 'banana', 'orange'])
+    expect('mango').not.toBeOneOf(new Set(['apple', 'banana', 'orange']))
     expect('mango').not.toBeOneOf([expect.any(Number)])
+    expect('mango').not.toBeOneOf(new Set([expect.any(Number)]))
     expect(null).not.toBeOneOf([undefined])
   })
 
@@ -655,7 +659,9 @@ describe('toBeOneOf()', () => {
     expect(3).toBeOneOf([0, 1, 2])
     expect(3).toBeOneOf([expect.any(String)])
     expect('mango').toBeOneOf(['apple', 'banana', 'orange'])
+    expect('mango').toBeOneOf(new Set(['apple', 'banana', 'orange']))
     expect('mango').toBeOneOf([expect.any(Number)])
+    expect('mango').toBeOneOf(new Set([expect.any(Number)]))
     expect(null).toBeOneOf([undefined])
   })
 
-- 
2.51.2