fix: correct maybeExecuteCount increment and add test for AbortSignal…

.changeset/humble-coats-shop.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/pacer': patch
+---
+
+Fixed a bug in AsyncDebouncer where getAbortSignal() incorrectly returned null due to an internal execution ID mismatch. Abort signals can now be properly attached to underlying async tasks.

packages/pacer/src/async-debouncer.ts

@@ -362,7 +362,7 @@ export class AsyncDebouncer<TFn extends AnyAsyncFunction> {
     ...args: Parameters<TFn>
   ): Promise<ReturnType<TFn> | undefined> => {
     if (!this.#getEnabled()) return undefined
-    const currentMaybeExecuteCount = this.store.state.maybeExecuteCount + 1
+    const currentMaybeExecuteCount = this.store.state.maybeExecuteCount
 
     try {
       this.#setState({ isExecuting: true })

packages/pacer/tests/async-debouncer.test.ts

@@ -1,4 +1,4 @@
-import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { afterEach, beforeEach, describe, expect, it, vi, } from 'vitest'
 import { AsyncDebouncer, asyncDebounce } from '../src/async-debouncer'
 
 describe('AsyncDebouncer', () => {
@@ -1358,5 +1358,22 @@ describe('asyncDebounce helper function', () => {
       expect(typeof debouncer.getAbortSignal).toBe('function')
       expect(debouncer.getAbortSignal()).toBeNull()
     })
+
+    it('should return an AbortSignal that can be used to cancel execution', async () => {
+      const debouncer = new AsyncDebouncer(
+        async () => {
+          const signal = debouncer.getAbortSignal()
+          expect(signal).toBeInstanceOf(AbortSignal)
+          return 'result'
+        },
+        { wait: 300 },
+      )
+
+      debouncer.maybeExecute()
+      vi.advanceTimersByTime(150)
+      const promise = debouncer.maybeExecute()
+      vi.advanceTimersByTime(300)
+      await promise
+    })
   })
 })