Block Fixup Commit Merge Action

Love using git commit --fixup or git commit --squash to make cleanups to your Git history, but forget to git rebase -i --autosquash master before merging?

Have I got a Github Action for you!

This Action is as an assistant to be sure you squash fixup commits before merging to your main branch.

Background

• The Git fixup workflow
• Git commit fixup and autosquash
• GIT tip : Keep your branch clean with fixup and autosquash
• You should use rebase/fixup in IntelliJ IDEA more often - Applicable to any use of git.
• Fixup your Code Reviews with git rebase --autosquash

Setup

Create a file in your project named: .github/workflows/git.yml Add the following:

name: Git Checks

on: [pull_request]

jobs:
  block-fixup:
    runs-on: ubuntu-18.04

    steps:
    - uses: actions/checkout@v2.0.0
    - name: Block Fixup Commit Merge
      uses: 13rac1/block-fixup-merge-action@v2.0.0

Optionally, setup Branch Protection to block merging of PRs against the master branch with fixup! commits.

Example PR blocked by a fixup! commit:

Why

Change Requests are part of a Pull Request code review. There are multiple methods to make the updates, some are better than others. The regular method is to add additional fix/update commits, including commit message titles such as "Code Review changes." There's a better way.

Git commits are the historical record of project. The commit messages tell a story, each commit or Pull Request describing a change. FutureYou™ and CurrentCoWorkers™ needs to know the end result of each change, but no one cares about edits required to make that change. We just want to read the book, no one cares what the editor told the author while writing the book.

One solution is to use Github's "Squash merge" feature. This works well for small PRs. A few small commits can be squashed into a single commit. The "edits" removed.

The problem occcurs when you have multiple unique commits a PR: a dependency update, followed by a refactor, then a bug fix. It is all one contained change, but FutureYou™ may just want to see that bug fix. Keep it separate. A solution is using git rebase to edit commits during the code review; this becomes confusing for reviewers, commits can suddenly disappear. "Fixup Commits" are better.

Fixup Commits can added to the end of the git history during a code review, then squashed into their respective commits after the PR is approved. The workflow is:

1. Make a feature branch.
2. Add commits implementing features and fixing bugs. Rebase and force push all you want for now. This is your branch.
3. Create a Pull Request and add Reviewer(s.) Rebasing commits is not allowed for now. This is not just your branch.
4. Reviewer(s) request changes.
5. Create commits using git commit --fixup=<SHA> to prepare changes to existing commits. Make new commits only when the change is outside the scope of existing changes.
6. Reviewers see new commits and approve the PR.
7. This is your branch again. Clean up the history to make an ideal set of commits git rebase -i --autosquash, and merge.

Note: Rebasing is still allowed for the entire branch to integrate master branch changes as needed.

FAQ

When using as a required check of a Pull Request, how can it ever succeed once it fails?

A final squash and force push is required to clear the check failure before merge.

The historical unsuccessful check does not block the merge. Only the most recent Action run matters. Once the code review has been completed, the Pull Request approved, and all other Actions/Checks (Travis/Circle/Jenkins) pass, the final step is cleaning the history by applying the fixup commits:

git rebase -i --autosquash
git push origin HEAD -f

Then all checks re-run, and you can merge the Pull Request.

License

MIT