Add an option to force capitalizing the subject line

[novadev94]

This convention is well-known in the community and deemed a good practice in several articles related to Git commit messages, ex. https://cbea.ms/git-commit/#capitalize.

However, it's currently not possible to get it configured, due to Python stock regex module re limitations - we can't have a regex pattern that matches a Unicode uppercase character.

There're 2 possible approaches to this:

• Implement this as a rule and maybe a default one.

• Switch to regex module, which has richer regex support with full backward compatibility with the re module.

[sigmavirus24]

I don't think this must be done with regular expressions but it would be good to add even if it's off by default

[Bearwolves]

@novadev94 : Why is that not possible?

We are using following regex to check for uppercase character in the description from the conventional commit perspective https://www.conventionalcommits.org/en/v1.0.0/ . I think that's what you are calling subject.

[general]
...
contrib=contrib-title-conventional-commits

[title-match-regex]
# python-style regex that the commit-msg title must match
# Note that the regex can contradict with other rules if not used correctly
# (e.g. title-must-not-contain-word).
regex=^[a-z]+[(a-z)]*[!]*: [A-Z]+.*

[ignore-by-title]
# Ignore certain rules for commits of which the title matches a regex
# E.g. Match commit titles that start with "Release"
regex=^((?:Bump version from (.*) to)|(?:Bump version to)|(?:CHANGELOG\.md))(.*)

# Ignore certain rules, you can reference them by their id or by their full name
# Use 'all' to ignore all rules
ignore=contrib-title-conventional-commits, title-match-regex, body-min-length

What do I miss? :(

One thing to keep in mind, this new rule must not conflict with the contrib rules i.e. the conventional commits.

[novadev94]

@Bearwolves Yes, I should've called them "title" instead of "subject line" to match gitlint convention.
That conventional commit regex pattern has the same mentioned problem where [A-Z] only matches capital English letters, and doesn't match Ö for example.
That's a non-problem if we force commit messages to be English only, but imo that'd be too restrictive.

[Bearwolves]

@novadev94 : Got your point. Supporting other language/character shall be allowed, agreed!
Thanks for detailing!

[jorisroovers]

We can add this as a contrib rule.

I’ve quickly implemented this a user-defined rule. Can you please verify this works as expected?

# filename: captilized_title.py
from gitlint.rules import LineRule, RuleViolation, CommitMessageTitle

class CapitalizedTitle(LineRule):
    name = "capitalized-title"
    id = "UL1"
    target = CommitMessageTitle

    def validate(self, title, _commit):
        if (len(title) > 0 and not title[0].isupper()):
            return [ RuleViolation(self.id, "Title not capitalized", title) ]

        return []

Use this .gitlint config:

[general]
extra-path=my/path/captilized_title.py

This would need unit tests and docs. Happy to accept a PR if you’re up for it: https://jorisroovers.com/gitlint/contributing/#contrib-rules

[jorisroovers]

Bump @novadev94 :-)