This particular setup is quite specific and after scouring the internet, I couldn't find any similar resources. Hence, I decided to post it here in case it proves helpful to someone.
While there are numerous inquiries regarding Jest and the error message Async callback was not invoked, none seem to address the core issue of utilizing jest.useFakeTimers(). When employing fake timers, my function should execute instantaneously, yet for some reason Jest seems to be hanging.
I am using Jest version 26 and have manually specified to use modern timers.
Below is a comprehensive code snippet that showcases the problem:
jest.useFakeTimers('modern')
let setTimeoutSpy = jest.spyOn(global, 'setTimeout')
async function retryThrowable(
fn,
maxRetries = 5,
currentAttempt = 0
) {
try {
return await fn()
} catch (e) {
if (currentAttempt < maxRetries) {
setTimeout(
() => retryThrowable(fn, maxRetries, currentAttempt + 1),
1 * Math.pow(1, currentAttempt)
)
}
throw e
}
}
describe('retryThrowable', () => {
const fnErr = jest.fn(async () => { throw new Error('err') })
it('retries `maxRetries` times if result is Err', async () => {
jest.clearAllMocks()
const maxRetries = 5
await expect(retryThrowable(() => fnErr(), maxRetries)).rejects.toThrow('err')
for (let _ in Array(maxRetries).fill(0)) {
jest.runAllTimers()
await Promise.resolve() // https://stackoverflow.com/a/52196951/3991555
}
expect(setTimeoutSpy).toHaveBeenCalledTimes(maxRetries)
})
})
The complete error message reads as follows:
Timeout - Async callback was not invoked within the 5000 ms timeout specified by jest.setTimeout.Error: Timeout - Async callback was not invoked within the 5000 ms timeout specified by jest.setTimeout.
at mapper (../../node_modules/jest-jasmine2/build/queueRunner.js:27:45)
Any input or suggestions would be greatly appreciated.
edit 1: I have attempted using --detectOpenHandles but it did not provide any additional insights.
edit 2: Upon testing the above code snippet in a fresh project, it passed successfully. Therefore, the root cause of the issue must lie elsewhere in my Jest configuration. I will update this post with a solution once I identify the exact source of the problem.