From 51d3a3418f40ca54bbe209cc0d1f0b7e9579224c Mon Sep 17 00:00:00 2001
From: Hiroki Osame <hiroki.osame@gmail.com>
Date: Sun, 30 Aug 2026 08:13:42 +0900
Subject: [PATCH 1/3] feat: support disposable spies

---
 src/internal.ts    |  1 +
 src/spyOn.ts       |  3 +++
 test/index.test.ts | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/src/internal.ts b/src/internal.ts
index 511e85a..d3e4f18 100644
--- a/src/internal.ts
+++ b/src/internal.ts
@@ -68,6 +68,7 @@ export interface Spy<A extends any[] = any[], R = any>
 }
 
 export interface SpyImpl<A extends any[] = any[], R = any> extends Spy<A, R> {
+  [Symbol.dispose](): void
   getOriginal(): (...args: A) => R
   willCall(cb: (...args: A) => R): this
   restore(): void
diff --git a/src/spyOn.ts b/src/spyOn.ts
index 2b6fa7c..7bc138e 100644
--- a/src/spyOn.ts
+++ b/src/spyOn.ts
@@ -261,6 +261,9 @@ export function spyOn<T extends object, K extends string & keyof T>(
   ;(['restore', 'getOriginal', 'willCall'] as const).forEach((method) => {
     defineValue(spy, method, spy[SYMBOL_STATE][method])
   })
+  if (Symbol.dispose) {
+    defineValue(spy, Symbol.dispose, spy[SYMBOL_STATE].restore)
+  }
   return spy as any as SpyImpl
 }
 
diff --git a/test/index.test.ts b/test/index.test.ts
index c39080c..b95fe5c 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -82,6 +82,39 @@ test('can spy on method', () => {
   expect(method.results).toEqual([ok('a!'), ok('b!'), ok('C!'), error(err)])
 })
 
+test('restores mock on leaving a using scope', () => {
+  const obj = {
+    method: () => 'original',
+  }
+  const original = obj.method
+
+  {
+    using method = spyOn(obj, 'method').willCall(() => 'mocked')
+
+    expect(obj.method()).toBe('mocked')
+    expect(method.called).toBe(true)
+  }
+
+  expect(obj.method).toBe(original)
+})
+
+test('restores mock when a using scope throws', () => {
+  const obj = {
+    method: () => 'original',
+  }
+  const original = obj.method
+
+  expect(() => {
+    using method = spyOn(obj, 'method').willCall(() => 'mocked')
+
+    expect(obj.method()).toBe('mocked')
+    expect(method.called).toBe(true)
+    throw new Error('test')
+  }).toThrowError('test')
+
+  expect(obj.method).toBe(original)
+})
+
 test('resets all spies', () => {
   let one = {
     method(arg: string) {

From 4710013a7474a0451615f6996286bac3d80702b5 Mon Sep 17 00:00:00 2001
From: Hiroki Osame <hiroki.osame@gmail.com>
Date: Wed, 2 Sep 2026 17:36:47 +0900
Subject: [PATCH 2/3] fix: declare disposable symbol

---
 src/internal.ts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/internal.ts b/src/internal.ts
index d3e4f18..1f91fc8 100644
--- a/src/internal.ts
+++ b/src/internal.ts
@@ -1,6 +1,13 @@
 import { assert, define, defineValue, isPromise, isType } from './utils.js'
 import { SYMBOL_STATE } from './constants.js'
 
+// Support consumers whose standard library predates explicit resource management.
+declare global {
+  interface SymbolConstructor {
+    readonly dispose: unique symbol
+  }
+}
+
 interface GetState {
   <A extends any[], R>(spy: SpyInternalImpl<A, R>): SpyInternalImplState<A, R>
   <A extends any[], R>(spy: SpyInternal<A, R>): SpyInternalState<A, R>

From 673ea72e1ea6ca3906a03c3e571dcf49f32a4a1b Mon Sep 17 00:00:00 2001
From: Hiroki Osame <hiroki.osame@gmail.com>
Date: Wed, 2 Sep 2026 18:02:20 +0900
Subject: [PATCH 3/3] fix: preserve disposable type compatibility

---
 optional-types.d.ts |  4 ++++
 package.json        |  3 ++-
 src/internal.ts     | 13 ++++---------
 tsup.config.ts      |  1 +
 4 files changed, 11 insertions(+), 10 deletions(-)
 create mode 100644 optional-types.d.ts

diff --git a/optional-types.d.ts b/optional-types.d.ts
new file mode 100644
index 0000000..0e727b1
--- /dev/null
+++ b/optional-types.d.ts
@@ -0,0 +1,4 @@
+export interface Disposable {
+  // @ts-ignore -- Symbol.dispose might not be in user types
+  [Symbol.dispose]: () => void
+}
diff --git a/package.json b/package.json
index 6c2fdb5..1ad1e29 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,8 @@
   "module": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "files": [
-    "dist"
+    "dist",
+    "optional-types.d.ts"
   ],
   "engines": {
     "node": ">=14.0.0"
diff --git a/src/internal.ts b/src/internal.ts
index 1f91fc8..c886661 100644
--- a/src/internal.ts
+++ b/src/internal.ts
@@ -1,12 +1,6 @@
 import { assert, define, defineValue, isPromise, isType } from './utils.js'
 import { SYMBOL_STATE } from './constants.js'
-
-// Support consumers whose standard library predates explicit resource management.
-declare global {
-  interface SymbolConstructor {
-    readonly dispose: unique symbol
-  }
-}
+import type { Disposable } from '../optional-types.js'
 
 interface GetState {
   <A extends any[], R>(spy: SpyInternalImpl<A, R>): SpyInternalImplState<A, R>
@@ -74,8 +68,9 @@ export interface Spy<A extends any[] = any[], R = any>
   nextResult(result: R): this
 }
 
-export interface SpyImpl<A extends any[] = any[], R = any> extends Spy<A, R> {
-  [Symbol.dispose](): void
+export interface SpyImpl<A extends any[] = any[], R = any>
+  extends Spy<A, R>,
+    Disposable {
   getOriginal(): (...args: A) => R
   willCall(cb: (...args: A) => R): this
   restore(): void
diff --git a/tsup.config.ts b/tsup.config.ts
index eb741a2..48d532b 100644
--- a/tsup.config.ts
+++ b/tsup.config.ts
@@ -2,6 +2,7 @@ import { defineConfig } from 'tsup'
 
 export default defineConfig({
   entryPoints: ['src/index.ts'],
+  external: ['../optional-types.js'],
   outDir: 'dist',
   format: ['esm'],
   tsconfig: './tsconfig.json',