Jest v26 is failing when run without cli options

🐛 Bug Report

When running the jest without cli options, it’s failing.

receiving following message in console

> jest

● Unrecognized CLI Parameters:

  Following options were not recognized:
  ["run-in-band", "test-location-in-results"]

  CLI Options Documentation:
  https://jestjs.io/docs/en/cli.html

npm ERR! Test failed.  See above for more details.

Problem is with version 26.0.1 (and 26.0.0). Same scenario is working with version 25.5.4.

To Reproduce

Followed the docs of jest. https://jestjs.io/docs/en/getting-started

Expected behavior

When no option is set, it is expected to run all tests.

Link to repl or repo (highly encouraged)

https://github.com/basarbk/jest-without-params-fail

envinfo

System: OS: Windows 10 10.0.10240 CPU: (4) x64 Intel® Core™ i5-6300U CPU @ 2.40GHz Binaries: Node: 12.13.1 - C:\Program Files\nodejs\node.EXE npm: 6.13.1 - C:\Program Files\nodejs\npm.CMD npmPackages: jest: ^26.0.1 => 26.0.1

[rasgele]

I’ve experienced same. Problems is with host locale and camelcase dependency. validateCLIOptions method in jest-validate\build\validateCLIOptions.js calls camelcase for each argv and tries to match them with allowed options. (see [this] line)(https://github.com/facebook/jest/blob/63ebaa6e3848ddf228b1acc6f870c7eaca34e46c/packages/jest-validate/src/validateCLIOptions.ts#L81) When it calls camelcase for arg run-in-band, camelcase returns runİnBand (capital ‘i’ in Turkish) if host has ‘tr-TR’ locale. And runİnBand is not one of allowed options (although runInBand is).

Workaround for Win10: Settings > Region & Language > Adminstrative language settings > Formats. Set Format to English (United States). That changes locale of node to en-US.

I guess proper solution would be camelcase providing locale option and jest-validate just provides en-US as locale.

[vahdet]

In package.json, adding --runInBand option is also a legit workaround for the time being. Adding that, the options won’t be added behind the scene, and there will be no Turkish char problem:

/*package.json*/
"scripts": {
  "test": "jest --runInBand"
}

But expect a longer time to complete as it runs tests one by one