fix fakeTimer problem

add new fakeTimer test and revise the function

add advanceTime

Author: Lei Chen

src/__tests__/asyncHook.fakeTimers.test.ts

@@ -51,6 +51,41 @@ describe('async hook (fake timers) tests', () => {
 
       expect(complete).toBe(true)
     })
+
+    test('should waitFor arbitrary expectation to pass when fake timers are not advanced explicitly', async () => {
+      const fn = jest.fn().mockReturnValueOnce(false).mockReturnValueOnce(true)
+
+      const { waitFor } = renderHook(() => null)
+
+      await waitFor(() => {
+        expect(fn()).toBe(true)
+      })
+    })
+
+    test('should reject if timeout is passed close to when promise resolves', async () => {
+      const { waitFor } = renderHook(() => null)
+
+      let actual = 0
+      const expected = 1
+
+      setTimeout(() => {
+        actual = expected
+      }, 101)
+
+      let complete = false
+
+      await expect(
+        waitFor(
+          () => {
+            expect(actual).toBe(expected)
+            complete = true
+          },
+          { timeout: 100, interval: 50 }
+        )
+      ).rejects.toThrow(Error('Timed out in waitFor after 100ms.'))
+
+      expect(complete).toBe(false)
+    })
   })
 })
 

src/core/asyncUtils.ts

@@ -7,11 +7,10 @@ import {
   AsyncUtils
 } from '../types'
 
-import { createTimeoutController } from '../helpers/createTimeoutController'
+import { createTimeoutController, DEFAULT_TIMEOUT } from '../helpers/createTimeoutController'
 import { TimeoutError } from '../helpers/error'
 
 const DEFAULT_INTERVAL = 50
-const DEFAULT_TIMEOUT = 1000
 
 function asyncUtils(act: Act, addResolver: (callback: () => void) => void): AsyncUtils {
   const wait = async (callback: () => boolean | void, { interval, timeout }: WaitOptions) => {
@@ -20,11 +19,11 @@ function asyncUtils(act: Act, addResolver: (callback: () => void) => void): Asyn
       return callbackResult ?? callbackResult === undefined
     }
 
-    const timeoutSignal = createTimeoutController(timeout)
+    const timeoutSignal = createTimeoutController(timeout, false)
 
     const waitForResult = async () => {
       while (true) {
-        const intervalSignal = createTimeoutController(interval)
+        const intervalSignal = createTimeoutController(interval, true)
         timeoutSignal.onTimeout(() => intervalSignal.cancel())
 
         await intervalSignal.wrap(new Promise<void>(addResolver))

src/helpers/createTimeoutController.ts

@@ -1,9 +1,28 @@
 import { WaitOptions } from '../types'
+import { jestFakeTimersAreEnabled } from './jestFakeTimersAreEnabled'
+const DEFAULT_TIMEOUT = 1000
 
-function createTimeoutController(timeout: WaitOptions['timeout']) {
+function createTimeoutController(
+  timeout: WaitOptions['timeout'] = DEFAULT_TIMEOUT,
+  allowFakeTimers: boolean
+) {
   let timeoutId: NodeJS.Timeout
   const timeoutCallbacks: Array<() => void> = []
+  let finished: boolean = false
 
+  const advanceTime = async (currentMs: number) => {
+    if (currentMs <= timeout) {
+      jest.advanceTimersByTime(1)
+
+      await Promise.resolve()
+
+      if (finished) {
+        return
+      }
+      // eslint-disable-next-line @typescript-eslint/no-unused-vars
+      await advanceTime(currentMs + 1)
+    }
+  }
   const timeoutController = {
     onTimeout(callback: () => void) {
       timeoutCallbacks.push(callback)
@@ -19,15 +38,23 @@ function createTimeoutController(timeout: WaitOptions['timeout']) {
             timeoutCallbacks.forEach((callback) => callback())
             resolve()
           }, timeout)
+
+          if (jestFakeTimersAreEnabled() && allowFakeTimers) {
+            advanceTime(0)
+          }
         }
 
         promise
           .then(resolve)
           .catch(reject)
-          .finally(() => timeoutController.cancel())
+          .finally(() => {
+            finished = true
+            timeoutController.cancel()
+          })
       })
     },
     cancel() {
+      finished = true
       clearTimeout(timeoutId)
     },
     timedOut: false
@@ -36,4 +63,4 @@ function createTimeoutController(timeout: WaitOptions['timeout']) {
   return timeoutController
 }
 
-export { createTimeoutController }
+export { createTimeoutController, DEFAULT_TIMEOUT }

src/helpers/jestFakeTimersAreEnabled.ts

@@ -0,0 +1,13 @@
+export const jestFakeTimersAreEnabled = () => {
+  /* istanbul ignore else */
+  if (typeof jest !== 'undefined' && jest !== null) {
+    return (
+      // legacy timers
+      jest.isMockFunction(setTimeout) ||
+      // modern timers
+      Object.prototype.hasOwnProperty.call(setTimeout, 'clock')
+    )
+  }
+  // istanbul ignore next
+  return false
+}