CI Test Suite Hangs and Is Killed

By Kaveh Alemi·Latchkey

The test process stopped making progress until the runner killed it on timeout. The usual cause is an open handle or a test waiting on something that never resolves; sometimes a transient infra stall is to blame.

What this error means

Tests print output, then stop, and the step is eventually cancelled for timing out. A deterministic hang reproduces every run; a transient stall (slow service, blip) clears on re-run.

PASS  src/a.test.ts
Jest did not exit one second after the test run completed.
##[error] The action has timed out.

Common causes

Open handles keep the process alive

Unclosed servers, DB connections, timers, or watchers prevent the runner from exiting, so it hangs until killed.

A test waits on something that never arrives

A missing mock, an unfulfilled promise, or a dependency that never becomes ready blocks forever.

How to fix it

Find the stuck test and open handles

Surface what keeps the process alive.

jest --detectOpenHandles --runInBand --testTimeout=30000

Close resources and bound waits

1. Close servers, DB pools, and timers in teardown.
2. Add per-test timeouts so a stuck test fails fast.
3. Ensure mocks/fixtures resolve so nothing waits forever.

How to prevent it

• Run with --detectOpenHandles periodically.
• Always tear down external resources.
• When the hang is caused by a transient infra stall (e.g. a service slow to respond), managed runners detect the mechanical blip and automatically retry, so a one-off stall does not fail the build.

Frequently asked questions

Related guides

References

• GitHub Actions documentation