commitMsg.md

📨 CommitMsg

Overview

The main functionality of commitlint is to directly lint commit messages. The very first instance of the commit is on the creation of the commit.

There are four git hooks that are triggered on commit: pre-commit, prepare-commit-msg, commitMsg and post-commit. More info can be found (here). The commitMsg hook is the one we care about because it is triggered last in the commit process.

Thus, first off, we setup the script to run on the commitMsg hook. The script is called commitlint:commitMsg.

The approach we are taking for this hook is to have a permissive linting rule so that developers can do intermediate commits that would be fixed prior to the push. We still need linting to avoid making the fixing of those commits a pain for the developers.

The script is mainly a call to commitlint with a specific configuration:

{
  ...,
  "scripts": {
    ...,
    "commitlint:commitMsg": "commitlint -g .commitlint/commitMsg.config.ts"
  },
  ...,
}

Then, after having the script setup (configuration walk-through can be found on the next section) we need to configure the git hook with husky.

Since, at the time of the writing we use Husky's 4th version, the configuration of Husky is made on the package.json. For simplicity, we choose to keep it with the 4th version but the last version is the 8th.

The setup is the following:

{
  ...,
  "husky": {
    "hooks": {
      ...,
      "commitMsg": "yarn commitlint:commitMsg -E HUSKY_GIT_PARAMS"
    }
  },
}

where the -E HUSKY_GIT_PARAMS is there to pass the commit message to the hook.

Configuration

As we explained in the document on commitlint, the two main components of the configuration are: rules and parserPreset. For these we choose:

• permissiveCommitRules as script's rules
• Our own's default parserPreset as parserPreset

From these configurations, there are a few important ones.

Permissive Commit Type String Array

This array extends the array that is the base of our convention and adds the following three types:

• fixup
• stash
• wip

These types are typical while working on a feature before submitting the changes for review.

Header Pattern

const commitHeaderPattern = /^(\w*)(?: \(([\w$.\-*/ ]*)\))?: (.+)$/;

The regex is designed to get these three groups:

• type
• scope
• subject

The structure that they follow is: <type>(<scope>): <subject>