STORY-TELLING WITH GIT REBASE Elle Meredith @aemeredith Blackmill @blackmillco 

Complexity 

Communicate 

Version Control System 

A project’s history is its most valuable documentation Ref: https://mislav.net/2014/02/hidden-documentation/ 

Kept forever 

Always in sync with the code 

Are available to everyone 

Searchable 

$ git log --grep regexp 

SMALL COMMITS 1 

commit [REDACTED] Date: [REDACTED] - add promotions to custom brand bundles - add bundle promotions to custom brands - generate unique custom promo code key - remove validation for nested create - remove binding.pry - update to allow default bundle (no promo) - refactor for empty promotion - tmp precompile assets - refactor dynamic promo code - adding tracking, top/bottom code - removing unused method calls, redundant migration - use scope - style with Rubocop validation - update asset path, fix broken specs - tmp disable integration spec 20 files changed, 349 insertions(+), 129 deletions(-) 

How big or small should a commit be? 

$ git add -p 

Image credit: http://www.artslife.com/2014/09/22/people-places-steve-mccurry-alla-south- bank-tower- no-al-279/ GOOD COMMIT MESSAGES 2 

Ref: http://stevetarver.github.io/2016/02/19/intentional-git-comments.html Image credit: https://burst.shopify.com/photos/train-turning-through-fog 1. Clarity of intent 2. Clarity of thought 3. Ability to reason about the code 

Ref: https://github.com/kristinabrown/dinner-dash/commits/master?page=5 

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$ Fix failed specs 

$ Fix this 

$ Fix stuff 

$ Changed stuff 

$ Testing git push 

$ Adjust css 

$ Bug fix 

$ More work 

$ Minor changes 

$ Work on feature XYZ 

$ Change X constant to be 10 

$ Whoops 

$ Should work now 

$ WTF? Ref: https://www.codelord.net/2015/03/16/bad-commit-messages-hall-of-shame/ 

Image credit: https://weheartit.com/entry/104254659 

ANSWER 5 QUESTIONS Why is this change necessary? How does it address the issue? What side e ects does this change have? Were other solutions considered? Include a reference [to a discussion, resource, ticket ] Ref: https://robots.thoughtbot.com/5-useful-tips-for-a-better-commit-message 

Present-tense summary under 50 characters * More information about commit (under 72 chars). * More information about commit (under 72 chars). http://project.management-system.com/ticket/123 

Present-tense summary under 50 characters * More information about commit (under 72 chars). * More information about commit (under 72 chars). http://project.management-system.com/ticket/123 

Present-tense summary under 50 characters * More information about commit (under 72 chars). * More information about commit (under 72 chars). http://project.management-system.com/ticket/123 

commit [REDACTED] Author: Elle Meredith Date: [REDACTED] Add author's name to opportunity form - This input field is disabled - so that the user cannot edit the field - It displays the author's name on: - create a new opportunity - edit an existing opportunity - reposting an opportunity - If the author doesn't have a first or last name, display the author's email instead Trello: https://trello.com/c/12345 

1. Add (340 times) 2. Update (339 times) 3. Remove / Delete (135 times) 4. Fix (132 times) 5. Use (76 times) 6. Style (56 times) 7. Allow (53 times) 8. Bump (50 times) 9. Show (44 times) 10. Refactor / Clean (35 times) Apply / Change / Con gure / Create / Deprecate / Disable / Display / Drop / Enable / Ensure / Extract / Handle / Improve / Increase / Limit / Link / Make / Migrate / Rename / Set / Skip / Sort / Support / Validate / Wire 

SMALL FEATURE BRANCHES 3 

Encapsulation 

Pull requests and code reviews 

1. Create a new branch $ git checkout -b em-feature-branch 

2. Update the branch, commit new changes $ git status $ git add $ git commit 

3. Push changes in the branch to `origin` $ git push -u origin em-feature-branch or $ git push origin head 

4. Open a PR for feedback 

5. Implement changes based on feedback 

6. Rebase master on the branch interactively and push updated branch back up $ git rebase -i master $ git push origin head -f 

6. Rebase master on the branch interactively and push updated branch back up $ git rebase -i master $ git push origin head -f 

7. Then fast forward merge to master $ git checkout master $ git merge --ff-only em-feature-branch 

8. Lastly clean up the branches $ git push origin :em-feature-branch $ git branch -d em-feature-branch Ref: https://github.com/thoughtbot/guides/tree/master/protocol/git 

MERGING VS REBASING 

$ git merge --no-ff em-feature-branch 

Image credit: https://www.atlassian.com/git/tutorials/merging-vs-rebasing 

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Rebasing 

$ git rebase -i origin/master 

$ git rebase --continue $ git rebase --abort 



Rebase 34020519..5eac86e0 onto 34020519 (2 commands) Commands: p, pick = use commit r, reword = use commit, but edit the commit message e, edit = use commit, but stop for amending s, squash = use commit, but meld into previous commit f, fixup = like "squash", but discard this commit's log message x, exec = run command (the rest of the line) using shell d, drop = remove commit l, label = label current HEAD with a name t, reset = reset HEAD to a label m, merge [-C | -c ] [# ] create a merge commit using the original merge commit's message (or the oneline, if no original merge commit was specified). Use -c to reword the commit message. These lines can be re-ordered;\they are executed from top to bottom. If you remove a line here THAT COMMIT WILL BE LOST. However, if you remove everything, the rebase will be aborted. Note that empty commits are commented out 

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Auto-squash and xup Ref: https://robots.thoughtbot.com/autosquashing-git-commits 



$ git commit --fixup $ git rebase --interactive --autosquash master 

$ git config --global rebase.autosquash true 

Rebase often to grab recent updates from `master` Use rebase when you want to keep a linear commit history Never use rebase on a public/shared branch- i.e. never rebase `master` 

WASH, RINSE, AND REPEAT 

Make small feature- speci c commits 

Write good commit messages 

Work in small thematic feature branches 

Rebase frequently to incorporate upstream changes 

Review and revise history before sharing 

Keep history linear 

Auto-squash commits 

THANK YOU! Elle Meredith @aemeredith Blackmill @blackmillco Edward watching over my sourdough