Error: Cannot find module 'prettier' with @wordpress/eslint-plugin v3.4.0

[kasparsd]

Describe the bug

See this example repository with the minimum setup to replicate the issue:
https://github.com/kasparsd/wordpress-eslint-plugin-prettier

Running eslint with .estlintrc.js config set to:

{
	"extends": [ "plugin:@wordpress/eslint-plugin/recommended" ]
}

and @wordpress/eslint-plugin as a development dependency set to version ^3.4.0 produces the following error:

Error: Cannot find module 'prettier'
Occurred while linting /Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/src/script.js:1
    at Function.Module._resolveFilename (module.js:548:15)
    at Function.Module._load (module.js:475:25)
    at Module.require (module.js:597:17)
    at require (/Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/node_modules/v8-compile-cache/v8-compile-cache.js:161:20)
    at Program (/Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/node_modules/eslint-plugin-prettier/eslint-plugin-prettier.js:162:26)
    at listeners.(anonymous function).forEach.listener (/Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/node_modules/eslint/lib/linter/safe-emitter.js:45:58)
    at Array.forEach (<anonymous>)
    at Object.emit (/Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/node_modules/eslint/lib/linter/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/node_modules/eslint/lib/linter/node-event-generator.js:254:26)
    at NodeEventGenerator.applySelectors (/Users/kaspars/Projects/wp-scripts-eslint-prettier-bug/node_modules/eslint/lib/linter/node-event-generator.js:283:22)
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! @kasparsd/[email protected] lint: `eslint ./src`
npm ERR! Exit status 2
npm ERR! 
npm ERR! Failed at the @kasparsd/[email protected] lint script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/kaspars/.npm/_logs/2020-02-04T10_54_35_609Z-debug.log

See the output on Travis:
https://travis-ci.com/kasparsd/wp-scripts-eslint-prettier-bug/jobs/283358536#L519-L538

Downgrading @wordpress/eslint-plugin to version 3.3.0 fixes the problem -- see this pull request:

kasparsd/wordpress-eslint-plugin-prettier#1

and the Travis CI output for the change:

https://travis-ci.com/kasparsd/wp-scripts-eslint-prettier-bug/jobs/283361201#L463-L467

To reproduce

Steps to reproduce the behavior:

1. Clone the sample repository git clone https://github.com/kasparsd/wordpress-eslint-plugin-prettier
2. Run npm install
3. Run npm run lint

Expected behavior

eslint runs as expected.

Desktop (please complete the following information):

• macOS 10.15.3
• Terminal
• node v8.17.0, npm 6.13.6.

[kasparsd]

Could this be related to #18048 #19963?

[ntwb]

p.s Thanks for the contribution and bonus points for the demo repo, thanks 💯

[marekdedic]

Hi, I'm seeing the issue again with version 4.0.0

[gziolo]

Hi, I'm seeing the issue again with version 4.0.0

Prettier is now listed as the dependency of @wordpress/eslint-plugin. Are you using npm 6.9.0 or later?

https://unpkg.com/browse/@wordpress/[email protected]/package.json

[marekdedic]

Hi,
I am a bit confused now... The CI for updating the package from 3.4.1 to 4.0.0 failed:

https://circleci.com/gh/skaut/skaut-google-drive-gallery/3451

and when I SSH into it, I can confirm npm is on version 6.13.4. When I do npm install it says

npm WARN [email protected] requires a peer of prettier@>= 1.13.0 but none is installed. You must install peer dependencies yourself.

npm update doesn't do anything.

However, locally, everything runs OK on the same branch.... Any ideas?

[ocean90]

I was still getting this error when @wordpress/babel-preset-default was also added in devDependencies.

  "devDependencies": {
    "@wordpress/babel-preset-default": "^4.10.0",
    "@wordpress/scripts": "^7.1.0"
  }

Removing @wordpress/babel-preset-default fixed the issue for me. Also had to delete node_modules first because npm i only returned

npm WARN [email protected] requires a peer of prettier@>= 1.13.0 but none is installed. You must install peer dependencies yourself.

[marekdedic]

I can confirm that purging node_modules worked for me. Didn't realize they were cached by the CI...

My mistake, sorry.