Jest complains about memory leak

[zaqqaz]

Steps to reproduce:

1. add jest-environment-jsdom-fourteen to the project
2. run jest with --detectLeaks flag

Result:

  Your test suite is leaking memory. Please ensure all references are cleaned.

    There is a number of things that can leak memory:
      - Async operations that have not finished (e.g. fs.readFile).
      - Timers not properly mocked (e.g. setInterval, setTimeout).
      - Keeping references to the global scope.

[ianschmitz]

Thanks for filing the issue @zaqqaz.

I've copied the latest logic from jest-environment-jsdom which I believe has sorted the issue.

I have published 1.0.0-alpha.0 which has removed the warning in my testing. Would you mind trying out the new version and let me know if it fixes the warning?

[ianschmitz]

I've done some more testing and it appears that i'm still seeing the warning. The warning disappears when using the same version of jsdom that Jest uses. However when i use 14 the warning appears.

Looks like it will need some more investigation.

[ianschmitz]

/cc @SimenB sorry to ping you. Wanted to bring to your attention as you guys might run into this when you eventually drop Node 6 support and bump jsdom.

From what I can tell this project (as well as jest-environment-jsdom) is following the recommended practices from jsdom: https://github.com/jsdom/jsdom#closing-down-a-jsdom.

Possibly related issues:
jsdom/jsdom#2198
jsdom/jsdom#2370

[SimenB]

Does it happen with jsdom 15?

[ianschmitz]

It does indeed. https://github.com/theneva/jest-environment-jsdom-thirteen also gives the same memory leak warning.

I have a package up for jsdom 15 which has identical source to this one - https://github.com/ianschmitz/jest-environment-jsdom-fifteen.

[SimenB]

Odd - just empty test and jest's own source for the env but using a newer jsdom? I'd have to dig into it