blog/content/posts/git-tips-global-precommit-hook.md

title	date	tags
Git Tips - Global Pre-commit Hooks	2020-01-01T21:00:39Z	git testing bash

Git hooks are a feature of the Git VCS that allow you to fire off custom logic on the client side when you take actions in your repository. These are shell scripts in the .git/hooks/ directory of your repository, but they can also exist in your home directory at ~/.githooks/.

Any hooks found in ~/.githooks/ are executed globally, this makes it easy to setup a custom workflow that is consistent across your entire machine.

Automatically lint and test on commit

One of my favorite hooks is a ~/.githooks/pre-commit hook that auto runs test and lint commands from a makefile or package.json if they're found:

{{<highlight bash "linenos=table">}}
#!/usr/bin/env bash

if [ -f "$PWD/makefile" ] && [ ! -z "$(cat $PWD/makefile | grep '^lint:')" ]; then
    echo "running make lint"
    make lint
elif [ -f "$PWD/package.json" ] && [ ! -z "$(cat $PWD/package.json | grep "^\"lint\":")" ]; then
    echo "running npm run lint"
    npm run lint
fi

if [ -f "$PWD/makefile" ] && [ ! -z "$(cat $PWD/makefile | grep '^test:')" ]; then
    echo "running make test"
    make test
elif [ -f "$PWD/package.json" ] && [ ! -z "$(cat $PWD/package.json | grep "^\"test\":")" ]; then
    echo "running npm run test"
    npm run test
fi
{{</highlight>}}

If the test or lint command fails then the git commit command fails. If I absolutely need to commit something in spite of the lint/test results I can do git commit --no-verify to skip the pre-commit hook.