Automatically git-blame-ignore style tweaks

A post-commit hook to add an entry to .git-blame-ignore-revs for pure formatting commits

Now you can upgrade to prettier v2 without ruining git blame!

PRs with changes to .git-blame-ignore-revs cannot squash+merge, otherwise you'll have to add more entries to .git-blame-ignore-revs in a follow up PR/commit.

What does it do, how does it work?

When you make a commit like this:

style(homepage): Sort imports

This post-commit hook will automatically add another commit like so:

chore(git-blame): Ignore previous style change

_{Commit message may be customized in a future version to be: chore(git-blame): Ignore "Sort imports"}

You do NOT need to use commitlint or commitizen to use this hook. It simply looks for commit messages starting with style: foo. (And probably also style(foo): bar, but that may come in a future version)

Setup

npm install git-blame-ignore-style-formatting-post-commit-hook --save-dev

yarn add git-blame-ignore-style-formatting-post-commit-hook --dev

If you are using husky (recommended), create hook like so:

mkdir .husky
mv .husky/post-commit .husky/old-post-commit;
rm .husky/post-commit
npx husky add .husky/post-commit 'GIT_ROOT="$(git rev-parse --show-toplevel)"';
npx husky add .husky/post-commit '$GIT_ROOT/node_modules/.bin/git-blame-ignore-style-formatting-post-commit-hook';
npx husky add .husky/post-commit '# Directly invoking module is faster than `yarn run git-blame-ignore-style-formatting-post-commit-hook`';
npx husky add .husky/post-commit "# (which makes sense, because it's skipping yarn\!)";

If not using husky, you can use this shell script as a starting point:

HOOKS_PATH=".git-hooks"
git config core.hooksPath $HOOKS_PATH
mkdir $HOOKS_PATH;
mv $HOOKS_PATH/post-commit $HOOKS_PATH/old-post-commit;
rm $HOOKS_PATH/post-commit
touch $HOOKS_PATH/post-commit;
chmod +x $HOOKS_PATH/post-commit;
echo '#!/usr/bin/env sh' >> $HOOKS_PATH/post-commit;
echo 'GIT_ROOT="$(git rev-parse --show-toplevel)"' >> $HOOKS_PATH/post-commit;
echo '' >> $HOOKS_PATH/post-commit;
echo '$GIT_ROOT/node_modules/.bin/git-blame-ignore-style-formatting-post-commit-hook' >> $HOOKS_PATH/post-commit;
echo '# Directly invoking module is faster than `yarn run git-blame-ignore-style-formatting-post-commit-hook`' >> $HOOKS_PATH/post-commit;
echo "# (which makes sense, because it's skipping yarn\!)" >> $HOOKS_PATH/post-commit;

If you don't already have a .git-blame-ignore-revs, one will be created for you before this script attempts to write to it:

Created empty .git-blame-ignore-revs file, and preinstall script to configure git to use it.

When you make a style: commit, it will now show something like this after you commit:

Adding .git-blame-ignore-revs entry for last commit. Reason: Starts with "style:"

When/if you are rebasing, and need to refresh the sha, you can simply reword your style: commits to re-run the post-commit hook:

// git-rebase-todo
-pick 7713c93 style: cleanup comments
-pick c2d2cf6 chore(git-blame): Ignore previous style change
+reword 7713c93 style: cleanup comments
+drop c2d2cf6 chore(git-blame): Ignore previous style change

It's also totally ok to wait till changes are merged to master/main before adding commit sha's to .git-blame-ignore-revs. This way, you don't have to worry about refreshing the sha when your mass cleanup commit sha changes. However, the goal of this git hook IS to automatically add entries to .git-blame-ignore-revs for you.