dequelabs/axe-core

axe-core timeout with mock timer in JS unit tests

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#3,055 opened on Jun 30, 2021

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Description

Product: axe-core

Expectation: axe-core does not timeout when timer is mocked in JS unit tests

Actual: When mock timers are used with axe (e.g. jest.useFakeTimers()), tests fail with error "Timeout - Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout.Timeout"

Motivation: Mocking timers are common in JS unit tests. Getting axe-core to work as expected even when mock timers are being used would be great. The timeout issue occurs even with other third-party mock timer libs such as @sinonjs/fake-timers - so it is not a problem just with Jest.

Something about mocking timers results in axe timeout - not sure why ?

Contributor guide

Research direction
Investigate how axe core uses timers internally. Trace the asynchronous operations that rely on real timers (e.g., setTimeout, setInterval) and identify where mock timers cause them to hang. Explore if there is a way to detect fake timers and work around them, or propose using process.nextTick or Promises instead of timers for internal timeouts.
Tech stack
javascriptjest
Domain
testing
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptJest
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65