Add an option to not throw an error on an unmatched pattern

[yvele]

The version of ESLint you are using.

ESLint: 5.1.0.

The problem you want to solve.

Since breaking behaviour change 8b7c6ea #7390 #10143 bundled in ESLint 5, a fatal error is thrown if any file pattern return no files.

My company is using a generic ESLint configuration/runner for all our projects, and we are pretty happy with that:

eslint \
  --ext .js --ext .jsx --ext .mjs \
  -- src test "packages/*/src" "package/*/test"

The problem is that not ALL of our projects matches the same patterns, and we got this error since we upgraded to eslint@5

No files matching the pattern "test" were found.
Please check for typing mistakes in the pattern.

We don't want to implement custom code to check for pattern existence before appending them to eslint CLI parameters (and we where really happy with eslint@4 behaviour on this particular case).

NOTE: This issue is a bit related to #9977

Your take on the correct solution to problem.

Add a CLI option (exactly like how proposed here) not to throw errors on unmatched patterns.

Something like --no-error-on-missing-files or --no-error-on-unmatched-pattern

[kaicataldo]

This seems reasonable to me as long as the default behavior remains unchanged. Let's see what others say.

Edit: typo

[platinumazure]

Agreed, it would be better to opt-in to this so that by default we are helping users avoid typos in their patterns.

[wei]

Ignore my comment. Thanks @not-an-aardvark , I was doing eslint ./*/ --ext .js --ignore-path .gitignore which worked in 4.19 but was breaking with a similar looking error. Changing it to eslint . --ext .js --ignore-path .gitignore fixed it.

[not-an-aardvark]

I don't think an error is thrown for nonexistent paths in .gitignore or .eslintignore. Are you sure that's creating an error?

[not-an-aardvark]

I think there are relatively few use cases for this option (one of which might be running eslint in an integration), but I don't object to adding it. That said, if you're encountering an error like this when running ESLint from the command line, the solution should usually be to stop trying to lint non-existing files, not to add a flag to make ESLint ignore your errors. This issue has a lot of 👍s in comparison with the narrowness of the use case, which makes me suspect that some people are misunderstanding what the error message is saying.

[isnifer]

Any update on this? I would like to describe my case:
I have a monorepo:

packages
  /api
  /app
  /shared
  /web

My web project runs in docker. And I don't add app code inside it. But my only script to lint all projects contains a path to app too. So, in v5 this command is broken inside docker.
I would like to see a parameter to not throw an error about unmatched paths.

[not-an-aardvark]

@isnifer Thanks for explaining your use case. I'm a bit confused -- if you don't have any app code, couldn't you simply remove the path to app/ from your script that lints all projects?

[isnifer]

@not-an-aardvark no, I have a code. But app and web are independent projects that use both shared and api. I don't use different configs and linter commands. I have the only config, the only lint command, and many projects.

.eslintrc
.eslintignore
packages/
package.json
lerna.json
...etc

Actually, I have found a solution for this:

# my v4 command to lint js
"lint": "eslint -c .eslintrc.js 'packages/api/**/*.js' 'packages/app/src/**/*.js' 'packages/app/__tests__/**/*.js' 'packages/app/scripts/**/*.js' 'packages/shared/**/*.js' 'packages/web/src/**/*.js' 'packages/web/__tests__/**/*.js' --cache"

# my v5 command to lint js
"lint": "eslint -c .eslintrc.js 'packages/**/*.js' --cache",

It works little bit longer when cold start, but then there is no problem.

[not-an-aardvark]

@isnifer I'm still not sure I understand -- what is the error message when you use your "v4 command" with ESLint v5? Is there a particular pattern that ESLint says isn't matching any files?

[isnifer]

@not-an-aardvark

> eslint -c .eslintrc.js 'packages/api/**/*.js' 'packages/app/src/**/*.js' 'packages/app/__tests__/**/*.js' 'packages/app/scripts/**/*.js' 'packages/shared/**/*.js' 'packages/web/src/**/*.js' 'packages/web/__tests__/**/*.js' --cache


Oops! Something went wrong! :(

ESLint: 5.2.0.
No files matching the pattern "packages/app/__tests__/**/*.js" were found.
Please check for typing mistakes in the pattern.

Because I don't need my RN app code inside docker for web

[not-an-aardvark]

So to make sure I understand, you want to use the same lint script in multiple environments, but in certain environments some of the files are absent?

[isnifer]

@not-an-aardvark correct. And I did it before v5.

[brunoscopelliti]

I've just upgraded to latest eslint@5.*, and this check is causing troubles to me as well.

I usually use eslint as: eslint app/** --ext .js.
Then in the .eslintignore file I exclude the undesired directory (eg. app/dist)...

In this case I get the following error:

No files matching the pattern "app/dist" were found.
Please check for typing mistakes in the pattern.

IMHO eslint shouldn't trigger the error for folders which are explicitly ignored. What do you think about this?

[brunoscopelliti]

Sorry for the double post.

I've also tried to run eslint as eslint app/folder1/** app/folder2/** app/file1 --ext .js.

That's not optimal cause if I add a folder, or file I've to update the build script as well, but I need a workaround for now.

However the above causes troubles as well, because I've some folders (eg. in app/folder2) which don't contain javascript file, but only json (eg. app/folder2/data/foo.json).

So I would really need a way to opt-out from this stricter check.

[not-an-aardvark]

Hi @brunoscopelliti, have you tried quoting the globs like eslint "app/**" --ext .js? It's possible that your shell is expanding the globs to a list of files before passing the files to ESLint, and the expanded list of files includes some folders that don't contain any lintable files.

[brunoscopelliti]

Hi @not-an-aardvark, I didn't know that was possible; quoting the globs worked for me. Thank you for the help.

[lucasrossini]

I've created a bash script as a workaround for this issue:

#!/bin/bash

GLOB_PATTERN=${1:-"."}

OUTPUT="$(script --quiet --return --command "eslint ${GLOB_PATTERN}" /dev/null)"
EXIT_CODE=${?}

if [[ "${EXIT_CODE}" == "2" ]]; then
  exit 0
fi

echo "${OUTPUT}"
exit "${EXIT_CODE}"

Just call it passing the desired pattern as an argument.
Hope it helps!

[kaicataldo]

This proposal has been accepted. PRs welcome!

[ncraley]

I'm gonna take a look at this over the weekend and see if it's something I can tackle