Scenario 3 — Interactive Rebase Cleanup

# Scenario 3 — Interactive Rebase Cleanup ## The brief Take a branch with messy commits and clean it up using interactive rebase. The standard "polish before PR" workflow. ## Step 1: Create a messy branch (10 min) ```bash mkdir rebase-drill && cd rebase-drill git init echo "# Project" > README.md git add . && git commit -m "Initial" # Pretend it's main git switch -c feature/login # Messy commits echo "function login() {}" > login.js git add . && git commit -m "Add login function" echo "function login(user, pass) {}" > login.js git commit -am "WIP" echo "function login(user, pass) { console.log('debug') }" > login.js git commit -am "WIP add debug" echo "function login(user, pass) { return validate(user, pass) }" > login.js git commit -am "fix login" echo "// Login module" > login.js echo "function login(user, pass) { return validate(user, pass) }" >> login.js git commit -am "Add comment" echo "TODO: write tests" > tests.js git add . && git commit -m "test stub" git log --oneline # Should show 6 commits with messy messages ``` ## Step 2: Interactive rebase (15 min) ```bash git rebase -i main ``` Editor opens with: ``` pick abc1 Add login function pick abc2 WIP pick abc3 WIP add debug pick abc4 fix login pick abc5 Add comment pick abc6 test stub ``` Edit to clean up: ``` pick abc1 Add login function fixup abc2 WIP fixup abc3 WIP add debug fixup abc4 fix login fixup abc5 Add comment pick abc6 test stub ``` Save and close. Git replays: - abc1 stays. - abc2, abc3, abc4, abc5 are squashed INTO abc1 (their messages discarded). - abc6 stays. Result: 2 clean commits. ```bash git log --oneline # def4 (HEAD -> feature/login) test stub # def5 Add login function ``` ## Step 3: Reword commit messages (10 min) ```bash git rebase -i main ``` ``` reword def5 Add login function reword def4 test stub ``` Git prompts for each message in turn. Edit them: ``` Add login function with validation Implements basic login: takes user and password, calls validate(). ``` ``` Add placeholder for login tests TODO: write actual tests for the login function. ``` Now your commits have meaningful messages. ## Step 4: Drop a commit (5 min) Add a bad commit: ```bash echo "secret_key=abc123" > .env git add . && git commit -m "Add config (FORGOT THIS WAS A SECRET)" ``` Realize the mistake. Drop it via rebase: ```bash git rebase -i main ``` Find the bad commit; change `pick` to `drop`: ``` pick xyz Add login function pick xyz test stub drop xyz Add config (FORGOT THIS WAS A SECRET) ``` Save. The commit and its changes are gone. Verify: ```bash git log --oneline # no bad commit ls # no .env file ``` ## Step 5: Reorder commits (5 min) Add a few more commits: ```bash echo "login_button" > ui.js git add . && git commit -m "Add login UI" echo "throttle login" > rate_limit.js git add . && git commit -m "Add login rate limit" ``` Rebase to reorder: ```bash git rebase -i main ``` Change: ``` pick a Add login function pick b test stub pick c Add login UI pick d Add login rate limit ``` To (reordering so rate limit comes before UI): ``` pick a Add login function pick d Add login rate limit pick c Add login UI pick b test stub ``` If commits don't conflict, reorder works cleanly. If they do, resolve as usual. ## Step 6: Autosquash workflow Make some commits, then mark fixups for an earlier commit: ```bash echo "// improved" >> login.js git commit --fixup= echo "// more notes" >> login.js git commit --fixup= git log --oneline # Shows: fixup! Add login function (etc.) ``` Auto-arrange in rebase: ```bash git rebase -i --autosquash main ``` Git pre-arranges the fixups next to their targets in the editor. You just save. ## Deliverables - Repository with clean commit history (2-4 atomic commits, good messages). - A `CLEANUP.md` describing: - The before-and-after. - What you used (`squash`, `fixup`, `drop`, `reword`, `edit`, reorder). - When `--autosquash` is useful. ## What you'll learn - The interactive rebase editor and commands. - `squash` vs `fixup` (fixup discards the message). - Dropping a commit via `drop` or deleting the line. - Rewording vs editing (reword = message only; edit = stop for changes). - `--autosquash` + `--fixup=SHA` for iterative cleanup. - The "polish before PR" mindset. ## Stretch - Try `edit` to actually split one commit into two (use git reset to un-commit, then commit selectively). - Use `--root` to rebase ALL commits including the first. - Practice on a branch with merge commits (use `--rebase-merges`).