are there side effects of running jest with --detectOpenHandles --forceExit?

Question

I'm using jest for testing, and in a few test scenarios I get the jest message:

Jest did not exit one second after the test run has completed. While taking Jest's recommendation to run with --detectOpenHandles and ending up with hanging test process that never ends, I saw other online suggestions to add the --forceExit option as well. Now the test ends and everything is ok.

It worths mentioning that all the tests are running properly and passing, with or without the --detectOpenHandles --forceExit options.

I wonder if is that considered as best practice in such cases? or is it just serving me as a "first aid"? What are the side effects of doing so?

Cheers,

Answer 1

From the documentation, the detectOpenHandles option is for:

Attempt to collect and print open handles preventing Jest from exiting cleanly. Use this in cases where you need to use --forceExit in order for Jest to exit to potentially track down the reason. This implies --runInBand, making tests run serially. Implemented using async_hooks, so it only works in Node 8 and newer. This option has a significant performance penalty and should only be used for debugging.

The forceExit option should never be used as a best practice, the only time you have to use is because:

• An async function did not finish
• A promise function did not finish
• A Websocket connection is still open
• A Database connection is still open
• Everything having a connect/disconnect methods did not disconnect before the end of the test