# Yarn test hangs when one more tests file is added **URL:** \ **Category:** Running Tests\ **Created:** [February 25, 2019, 8:35pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606 "2019-02-25T20:35:38Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 25, 2019, 8:35pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/1 "2019-02-25T20:35:38Z")
Hi All, I’m running a project that has several test suites (Jest), all passing locally. I have a step in my CircleCI job that simply runs `yarn test`. The problem is that the entire build hangs during the `yarn test` step. The tests all pass, but the step just hangs, and times out after 10 min. ![CircleCI](https://global.discourse-cdn.com/circleci/original/3X/e/4/e43c60614e2209d4650928191e7743c25e07d053.png) To make thing more interesting, if I remove one test suite file from my tests folder, the step will pass. I can remove any tests file, it will still pass. That means there is nothing wrong with my tests. Also, if I remove one file, and add a new file with just one dummy test, the step will hang again. What am I overlooking? (NOTE: using a free account) Thanks! ---
**Author:** ![drazisil](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/drazisil/32/24029_2.png) [@drazisil](https://discuss.circleci.com/u/drazisil)\ **Post date:** [February 26, 2019, 2:46pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/2 "2019-02-26T14:46:09Z")
That is strange. Are you running any browser tests? Those tend to hang in strange ways and can cause timeouts. ---
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 26, 2019, 3:52pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/3 "2019-02-26T15:52:50Z")
No, server side only. But it will also consistently succeed until I add one more test file. And then consistently hang. ---
**Author:** ![drazisil](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/drazisil/32/24029_2.png) [@drazisil](https://discuss.circleci.com/u/drazisil)\ **Post date:** [February 26, 2019, 3:53pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/4 "2019-02-26T15:53:40Z")
And it doesn’t matter what the test is? It can be any test? What about if you add a test and roll your cache keys? Any change? ---
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 26, 2019, 5:39pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/5 "2019-02-26T17:39:48Z")
I am not caching anything during this job. And yes, it doesn’t matter what the test is. I tried right now adding a file named dummy.test.ts with this content: `test('dummy', (done) => { done(); })` and the build got stuck again. the build before passed. ---
**Author:** ![drazisil](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/drazisil/32/24029_2.png) [@drazisil](https://discuss.circleci.com/u/drazisil)\ **Post date:** [February 26, 2019, 5:40pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/6 "2019-02-26T17:40:45Z")
What happens if you try SSH’ing in, does it still hang? Does it give more details, or can you add more verbosity? ---
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 26, 2019, 5:43pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/7 "2019-02-26T17:43:18Z")
I had much more verbosity, which I suppressed. Tried running Jest with --detectOpenHandles. It just hangs, nothing happens. I’d love some help trying to figure out how to troubleshoot via SSH. ---
**Author:** ![drazisil](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/drazisil/32/24029_2.png) [@drazisil](https://discuss.circleci.com/u/drazisil)\ **Post date:** [February 26, 2019, 5:45pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/8 "2019-02-26T17:45:06Z")
Sure, these steps [https://circleci.com/docs/2.0/ssh-access-jobs/](https://circleci.com/docs/2.0/ssh-access-jobs/) will walk you though how to SSH into the box. I would then suggest running the tests again to see where and how they hang. ---
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 26, 2019, 6:23pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/9 "2019-02-26T18:23:32Z")
Via SSH the tests pass 😕 (I ran them 3 times, just to make sure). When I ran ‘Rebuild with SSH’ I got this message during the tests (it wasn’t there before): `ENOMEM: not enough memory, read` ---
**Author:** ![drazisil](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/drazisil/32/24029_2.png) [@drazisil](https://discuss.circleci.com/u/drazisil)\ **Post date:** [February 26, 2019, 6:27pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/10 "2019-02-26T18:27:57Z")
Hrm. Can you [open a ticket with the build URL](https://support.circleci.com/hc/en-us/requests/new)? I’d like to take a look and see if I can spot anything strange. Please ping me the ticket number. ---
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 26, 2019, 6:32pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/11 "2019-02-26T18:32:32Z")
Ticket #47071 ---
**Author:** ![besquared](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/besquared/32/21534_2.png) [@besquared](https://discuss.circleci.com/u/besquared)\ **Post date:** [February 27, 2019, 5:32am UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/12 "2019-02-27T05:32:27Z")
I’m seeing the same thing with yarn test and jest v24… It’s really intermittent and sometimes just restarting the build a few times will make it work… Not sure what’s going on either… ---
**Author:** ![besquared](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/besquared/32/21534_2.png) [@besquared](https://discuss.circleci.com/u/besquared)\ **Post date:** [February 27, 2019, 5:49am UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/13 "2019-02-27T05:49:23Z")
Actually I think it’s related to the issue listed here [https://github.com/facebook/jest/issues/5239#issuecomment-355867359](https://github.com/facebook/jest/issues/5239#issuecomment-355867359) adding --runInBand to your jest command will fix it and dramatically speed up your tests. ---
**Author:** ![juvaly](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/juvaly/32/22017_2.png) [@juvaly](https://discuss.circleci.com/u/juvaly)\ **Post date:** [February 27, 2019, 6:40am UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/14 "2019-02-27T06:40:54Z")
For me the problem is very consistent. But I peeked at the github thread you linked, @besquared, and **setting -w=2 worked**! Edit for future readers: setting -w=2 limits the number or worker Jest uses to 2. I assume this can be raised to more workers in paid account with stronger machines, but 2 works great for free accounts, which run machines with 2 cores. ---
**Author:** ![besquared](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/besquared/32/21534_2.png) [@besquared](https://discuss.circleci.com/u/besquared)\ **Post date:** [February 27, 2019, 3:46pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/15 "2019-02-27T15:46:54Z")
For the record I found this solution in the CircleCI docs but just no in the place you’d expect… It was linked at the bottom of this article: [https://circleci.com/docs/2.0/collect-test-data/#jest](https://circleci.com/docs/2.0/collect-test-data/#jest) ---
**Author:** ![drazisil](https://sea2.discourse-cdn.com/circleci/user_avatar/discuss.circleci.com/drazisil/32/24029_2.png) [@drazisil](https://discuss.circleci.com/u/drazisil)\ **Post date:** [February 27, 2019, 3:48pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/16 "2019-02-27T15:48:58Z")
@besquared That’s good feedback. Our docs are open-source so PRs welcome, but where would be a better place to surface this information? ---
**Author:** ![system](https://global.discourse-cdn.com/circleci/original/3X/5/1/511608acda8e85906e15909b57bd0a46c1dbe291.png) [@system](https://discuss.circleci.com/u/system)\ **Post date:** [March 9, 2019, 3:48pm UTC](https://discuss.circleci.com/t/yarn-test-hangs-when-one-more-tests-file-is-added/28606/17 "2019-03-09T15:48:58Z")
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