fix: ignore empty commit messages #615

[ctomp]

bypass rules for completely empty commit messages (only of blank
lines/comments in message)

Description

A commit consisting of only newlines and/or comments (i.e. an empty commit) will bypass any rules and return as a valid commit. Empty commit messages will cause git to abort the commit, unless the user has specified the allow-empty-message option. The code change in this pull request preserves all git behavior.

I believe this is just a fix, and not a BREAKING CHANGE since it fixes an unintended error from occurring.

Motivation and Context

This change fixes #615 - it allows users to abort a commit without an error. A standard way to abort a commit once in the commit editor is to write an empty file, or a file consisting of only newlines and comments. Before this change, a user would encounter an error from the linter.

How Has This Been Tested?

I added two test cases to @commitlint/lint test file. They test the cases where a commit messages consists only of comments or where the commit message contains only comments and newlines.

I also manually tested several different commint message input files provided as input to @commitlint/cli command.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[marionebl]

Hey @ctomp, thanks for this stab at fixing #615!

This would allow empty commit messages in every case, while #615 describes an issue with aborting a commit by saving an empty commit via the invoked editor. This is the only way to abort an commit, thus we have to support this. Contrast this with e.g. git commit -m "", which should fail.

[ctomp]

@marionebl Thanks for taking a look! The way I interpreted it was that saving an empty commit in an editor should give the same result as if you had done git commit -m "". In the current release doing git commit -m "" passes the linter and defers to git to abort the message. Saving an empty commit via a text editor will have the same behavior - but usually people have a commit template that shows up as comments inside the editor so their commit isn't actually truly empty and that's why the behavior in the current release is different. git commit -m "" is the same as if saving an empty editor and I don't know if it's possible to differentiate between the two, so I was aiming to have the same behavior for both cases: let git deal with it.

Of course people could then override default git behavior and allow and empty commit message with allow-empty-message. I had then imagined a new rule type that disallows empty commit messages explicitly.

How would you like me to proceed? I could give it another stab, or close the pull request if you want.

[michaellopez]

I think aligning with git commit -m "" is the right thing to do. Thats what I expected to happen at least. With that said, after experimenting with our setup I want to differentiate between git commit -m "" and empty message from editor from git commit. The former has no "ongoing process" that the developer wants to abort, it's just ill intent. The later has an "ongoing process" of authoring a commit message. If you happen to change your mind about the commit because something in the template triggered it (or whatever), you want to abort. -m "" just wants to bypass the template and the thought process of if "abort or not".

Is it possible to tell them apart?

[ThisIsMissEm]

I'd encountered the error in #615 and was about to report it myself; Reading this, I don't think there is a difference between git commit -m "" and exiting the editor — functionally they're the same I think. In both cases, git will error out with "you need a commit message" type error, so I think it's just a case of not even bothering to try to lint an empty message.

[marionebl]

Took the liberty to update this to the changes of our TypeScript port. Also moved the creation of the LintOutcome object to a dedicated class.