Auto-fix by default?

[sindresorhus]

Most user's workflow; run npm test, encounter linter errors, then manually run xo --fix.

Is there any good reason not to just make XO default to --fix? And instead have a xo --no-fix flag to opt-out. Are there any downsides in doing this?

This could be problematic for a few rules, like ava/no-skip-test, as its auto-fixer would remove the skip before running the test, but we could have a list of things to not auto-fix by default.

[novemberborn]

I see linters as being checkers. I wouldn't expect them to just go and change my code.

Would you detect CI and raise errors rather than fixing?

[sindresorhus]

I see linters as being checkers. I wouldn't expect them to just go and change my code.

Can we change that perception? I see linters as helpers. Fixing my code is just helping me more.

Would you detect CI and raise errors rather than fixing?

Yes

[novemberborn]

Can we change that perception?

Prettier is more easily understood as a formatter.

I don't have hard feelings either way. Would be cool if I could disable the auto-fix behavior globally though.

[kevva]

There are also CI environments to take into account. Depending on what CI you run, you'd have to make sure to run xo with the --no-fix flag. We could probably check for this and skip setting the --fix flag if it's process.env.CI, but it might lead to some edge cases.

Then there are those cases where you are transitioning an existing code base to xo from another linter. In your first couple of runs you probably just want to run it and evaluate if you want to turn off some rules before settling for a config. This could cause some issues if it would fix a bunch of files automatically, since it's a pretty unexpected behaviour most linters don't employ.

Personally it boils down to mentality. I'm a bit wary of tools that make changes to my code without me explicitly telling them to.

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Oh, didn't refresh the page before commenting. I see @novemberborn brought up the question about CI environments already :).

[vadimdemedes]

I can’t come up with any reason not to do this!

[fregante]

There are more cases where you only need to verify the code without fixing it:

• CI, as mentioned before

• pre-commit hooks: if xo changes the code and pass the hook, I don't think the changes will get committed.

• Tools like np: lint passes, then np fails because suddenly the directory isn't clean.

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Most editors can be set to auto-run tools like xo to fix the code on save, I don't think it's a big deal to set that up or to run xo --fix when that behavior is wanted.

[SamVerschueren]

Not sure about this. On one side, I like the idea because like you say, it can only help you. On the other hand, I think there are quite a lot of edge cases, some already mentioned by others where it works against you instead of with you.

A way to test this would be to publish some kind of pre-release version with --fix on by default and start using it.

[fregante]

The idea has grown on me, is this worth a try in the wild?

If you can reliably detect CI, git and text editors plugins, the most common automated use cases won't be affected, so probably a try wouldn't ruin a lot of people's day 😅

• Tools like np: lint passes, then np fails because suddenly the directory isn't clean.

To counter my own point, np would fail anyway in this step—but at its appropriate test step rather than at a random later check. So technically not completely broken, just slightly less understandable.

[sindresorhus]

@bfred-it I'm not ready to experiment with this yet. I have too many things to deal with and I expect this to require a lot of follow up and tweaks.

[florianb]

I don't like the idea - i use xo to tackle my bad behaviors. If someone would want to autofix why not adding --fix to the test-call?

[coreyfarrell]

If I make changes to index.js and run xo without running git add index.js then xo could end up modifying my unstaged file. If this were done I would add --no-fix to all my npm test targets.

[mIkramAnsari]

How can we formate the code only without changing the code?

[fregante]

@mIkramAnsari https://prettier.io