Add "no_skip" whitelist/additive option for hooks and commands

[istrasci]

⚡ Summary

Create a no_skip ("enforce"?) whitelist/additive option for hooks and commands.

Value

Currently there is only a skip option for hooks and commands which is blacklist/subtractive behaviour. I often have commands that I want to execute only on particular branches. Since there is only a subtractive option, I have to implement additive behaviour myself by writing a custom script that checks the current git branch, and executes the command if I'm on one of the allowed branches. I'd rather not have to do that.

Common use case would be that I want to execute my test suite in a pre-commit hook only if I'm on master or hotfix/* branches. I cannot blacklist every other possible branch name, so I must create the workaround myself.

Behavior and configuration changes

Add a no_skip (or another word, but I can't find a good antonym for "skip") option that implements additive behaviour for hooks and commands.

[mrexox]

Hey! Thank you for the feature request. I like the word only, does it make sense to you?

So, you suggest to add something like this, right?

# lefthook.yml

pre-commit:
  only:
    - ref: master
    - ref: hotfix/*
  commands:
    test:
      only: 
        - ref: hotfix/*
      run: make test
    lint:
      run: make lint

I think this option should accept all possible skip values, but apply them the opposite way.

If you confirm, I will start working on this feature.

[istrasci]

@mrexox Yes, your understanding is correct. Accept all possible skip values, but apply them the opposite way. I think the word only is a good choice 👍.

Thank you for your consideration!

[mrexox]

Hey! The feature has just been released with v1.3.13, check it out! Docs: https://github.com/evilmartians/lefthook/blob/master/docs/configuration.md#only

[istrasci]

Awesome, thank you!