Solve `yarn.lock` or `package.json` conflicts without losing your mind

yarn.unlock.md

NOTE: This guide is ONLY for devs who don't want to edit their yarn.lock file by hand. If you don't care about that please carry on.

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So you've pulled the latest master

git checkout master
git pull

And checked out your favorite branch but when you try to merge master into it...

git checkout my-awesome-feature
git merge master

Uh-oh! Both your fave branch and master have changed stuff in yarn.lock

CONFLICT (content): Merge conflict in package.json
CONFLICT (content): Merge conflict in yarn.lock

Sure you could probably fix the package.json conflict "by hand" but the lockfile should not be touched 💩

All sorts of naughty thoughts might be going through your head at this point including conflict fix branches, merge stategies or even god-forbid... a rebase⏰⬅️🚗💨

But fear not my troubled friend, there's no need to go that far, here's how you can fix this in 3 easy steps:

1. Write down the exact package names and versions that your branch added/removed/upgraded (eg: left-pad@^1.1.3).
2. Checkout and stage package.json and yarn.lock from master.

git checkout --theirs package.json
git checkout --theirs yarn.lock
git add package.json yarn.lock

3. Re-apply the packages you wrote down in step 1 (eg: yarn add left-pad@^1.1.3).

Now the conflicts should be all gone and you're free to go on your way (commit the merge or fix other unrelated conflicts).

Just run yarn install. Yarn has a built-in mechanism to fix conflicts if it detects them present in the lock file.