ProTip: How To Split Large Branches Into Small Pull Requests

Large PRs are hard to review for a number of reasons I won’t go into, but let’s assume that the axiom is true that smaller PRs are better. One strategy I use to split a large feature branch into small PRs is detailed here. To keep things simple for the example I’m assuming that we’re branching from master to create feature branches.

Step 1: Create a patch against your base branch

$ git diff master my_large_feature_branch > ../my_pr_patch

Step 2: Checkout a new branch

Create a new branch that will contain a subset of the changes in my_large_feature_branch

$ git checkout master
$ git checkout -b small_pr_one

Step 3: Apply Changes Selectively

Now apply the patch to your new small_pr_one branch. This will apply all of the changes from my_large_feature_branch to disk and allow you to stage things that can go individually.

$ git apply ../my_pr_patch

Once you’ve staged and committed whatever you want for small_pr_one it’s time to clean up.

Step 4: Stash the Remaining Changes

To stash everything that isn’t staged, including untracked files, run the following command.

git stash --include-untracked --keep-index

Now small_pr_one is clean and you can open a PR against it. Next move on to small_pr_two through small_pr_n until complete.

Step 5: Repeat 3 & 4 Until Done

If the next set of changes can be made independently then open small_pr_two against master. If you need what was in small_pr_one to keep going just branch from there.

git checkout master
git checkout -b small_pr_two

You can use $ git stash show to list the remaining files in your stash. If you want to apply changes from the stash selectively you can use git checkout stash@{0} -- <your filename> to checkout an individual file from the stash. If you need to see a diff between what’s in the stash and your current branch run: git diff stash@{0} -- <your filename>

Additional Resources

Another approach you might want to try is Stacked PRs by Grayson Koonce: https://graysonkoonce.com/stacked-pull-requests-keeping-github-diffs-small/

I’ve used Stacked PRs a few times but tend to prefer keeping my branching structure shallow if possible so I normally use the approach shown above.

Happy Coding!

-g