jest --watch triggered by temp files

Question

I'm running Jest 26.4.2 on MacOS Catalina using Emacs as my text editor. When the watcher is running, any time Emacs creates a temp file jest will trigger a run. This leads to many runs triggering that tend to miss the actual file save event.

I'm running jest with npx jest --watch

I've tried various jest configs, the one that looked promising, testPathIgnorePatterns, did not help.

Emacs creates temp files by making a symlink with the pattern .#<target file name> that points to a files that ends with 5 digits. I've tried ignoring all these but it didn't help.

jest.config.js:

  watchPathIgnorePatterns: ['/[0-9]{5}/', '/#/'],
  testPathIgnorePatterns: ['/[0-9]{5}/', '/#/'],
  modulePathIgnorePatterns: ['/[0-9]{5}/', '/#/'],

Answer 1

The files created by my editor, Emacs / Spacemacs, are lock files. They are created and removed as soon as files are edited, saved or reverted.

I could not get jest to ignore them so I configured my Spacemacs TypeScript layer to not create them in TypeScript mode via (typescript :variables create-lockfiles nil).

Answer 2

Looking at a recent jest (26.6.1 in april 2021), the createHasteMap() function calls sane with an ignored composed from config.modulePathIgnorePatterns and config.watchPathIgnorePatterns (src). watchPathIgnorePatterns seems appropriate but I'm welcome to counter-advice.

jest.config.js

module.exports = {
  modulePathIgnorePatterns: [
    "\\/\\.#"
  ]
}

If for some reason, you have .../.#... paths in your directory hierarchy that you don't want to skip, you can create a more specific pattern using the keyword <rootDir>, which will be substituted to point to the root of your project. (If you also have a directory called <rootDir>, quit screwin' around.)

Answer 3

Looks like you forgot to add a dot and remove the slash at the very end (since it's a file not a folder)? So instead of /#/ it should be /.#? I'm not a regex master, so just created two files

• .#test.test.js
• test.test.js

and looks like the first one is ignored correctly (npm t -- --watch) with my package.json config. You can also try playing with a <rootDir>, or pass the config file directly using npm t -- --config jest.config.js

"jest": {
    "testPathIgnorePatterns": [
        "<rootDir>/.#",
        "/.#"
    ]
}