Tests failing only on WSL with 'Cannot find module'

Suddenly when running jest in my Angular app within a WSL terminal tests are failing at random with a variation of Cannot find module or No such file error message pointing at my node_modules folder. Note: I ran npm install within the WSL work space so I don’t believe it’s an issue of incompatibility between windows and unix installs. e.g.

# example of no such file error
ENOENT: no such file or directory, lstat '<root dir>/node_modules/tr46/lib/regexes.js'

      at Object.<anonymous> (node_modules/tr46/index.js:4:17)

# example of Cannot find module error
 Cannot find module '../start_of_week/index.js' from 'index.js'

      at Resolver.resolveModule (node_modules/jest-resolve/build/index.js:221:17)
      at Object.<anonymous> (node_modules/date-fns/start_of_iso_week/index.js:1:46)

I have not yet been able to find a pattern that is reproducible - the same tests aren’t failing each time. To add even more confusion when I run my tests with my IDE (pointing to the same exact node_modules folder) everything works without issue - and the problem doesn’t happen in our CI either. Here is the relevant sections of my package.json

"dependencies": {
    "@angular-devkit/core": "^0.7.5",
    "@angular-devkit/schematics": "^0.7.5",
    "@angular/animations": "6.1.3",
    "@angular/cdk": "^6.4.6",
    "@angular/cli": "6.1.4",
    "@angular/common": "6.1.3",
    "@angular/compiler": "6.1.3",
    "@angular/core": "6.1.3",
    "@angular/forms": "6.1.3",
    "@angular/http": "6.1.3",
    "@angular/platform-browser": "6.1.3",
    "@angular/platform-browser-dynamic": "6.1.3",
    "@angular/router": "6.1.3",
    "core-js": "^2.4.1",
    "date-fns": "^1.29.0",
    "normalize.css": "^7.0.0",
    "rxjs": "^6.2.2",
    "rxjs-compat": "^6.2.2",
    "zone.js": "^0.8.26"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.7.4",
    "@angular/compiler-cli": "6.1.3",
    "@angular/language-service": "6.1.3",
    "@angularclass/hmr": "^2.1.3",
    "@types/jest": "^23.3.2",
    "babel-preset-env": "^1.7.0",
    "codelyzer": "^4.3.0",
    "cz-conventional-changelog": "^2.1.0",
    "git-describe": "^4.0.3",
    "husky": "^0.14.3",
    "jasmine-marbles": "^0.3.1",
    "jest": "^23.5.0",
    "jest-preset-angular": "^6.0.0",
    "json-server": "^0.14.0",
    "lint-staged": "^7.2.0",
    "prettier": "^1.15.2",
    "protractor": "~5.1.2",
    "ts-node": "~3.2.0",
    "tslint": "~5.7.0",
    "tslint-angular": "^1.1.1",
    "tslint-config-prettier": "^1.12.0",
    "typescript": "2.9.2"
  },

[csaxe]

I had the same issue; resolved when IT allowed me to upgrade my machine to 1903.

[bvitale]

I don’t use jest-preset-angular but this ticket convinced me I wasn’t crazy when I was getting these same random file not found errors… when running Jest based tests on WSL.

I was able to resolve the issues with the latest Windows 10 updates. I think the root cause was this: https://github.com/Microsoft/WSL/issues/2712 https://docs.microsoft.com/en-us/windows/wsl/release-notes (search for 2712)

Hope this helps someone else.