kirill-kruchkov / git-rebase-intro-workshop

A working repository for an introduction to git rebase

Git rebase intro workshop

About

This is an introductory level workshop on using git rebase to keep your local changes up-to-date with a master branch and resolve conflicts.

This is an imaginary scenario and restrictions are here to help you focus on learning git rebase.

Read more about tidy git history in the article A tidy, linear git history.

Git Rebase

git-rebase - Reapply commits on top of another base tip

(https://git-scm.com/docs/git-rebase)

Resolving conflicts

When resolving conflicts during git rebase, HEAD ("current change") will be the tip of the branch you're adding commits to, and "Incoming change" will be (consequently) commits from the branch you are currently rebasing.

Goal

This repository consists of a number of branches. Each branch corresponds to a certain "feature", while all features contribute to writing an agile manifesto. You'll have to merge these branches to the release branch in a correct order (see below).

Result content

The result contents of the manifesto.md should look like this:

# Manifesto for Agile Software Development

We are uncovering better ways of developing

software by doing it and helping others do it.

Through this work we have come to value:


**Individuals and interactions** over processes and tools

**Working software** over comprehensive documentation

**Customer collaboration** over contract negotiation

**Responding to change** over following a plan


That is, while there is value in the items on

the right, we value the items on the left more.

Commit order

0. Create manifesto
1. Clean-up
2. Paragraph 1
3. Paragraph 2
4. Paragraph 3
5. Formatting
6. Title

Rules

1. You can use git rebase with any options for feature branches.
2. You can't use cherry-pick.
3. You can't commit anything.
4. Use git checkout manifesto && git merge --ff-only <feature-branch> to update the manifesto branch (let's imagine it's our GitHub merge PR button).

Preparation

git checkout master
chmod +x ./reinit.sh
./reinit.sh

Contributors

Thanks to @zoheiry and @ajantis for reviewing and commenting on the original implementation.

---

Walkthrough

1. Paragraph 1 - Rebase with conflicts

git checkout manifesto

Notice that paragraph-1 and manifesto both contain the Create manifesto commit:

git log --graph --pretty=oneline manifesto paragraph-1

Let's try merging (that's what would normally happen instide the GitHub):

git merge --ff-only paragraph-1

You'll see a message that fast-forward merge is not possible (due to conflicts).

Now we can start rebasing. Our goal is to put paragraph-1 on top of manifesto.

git checkout paragraph-1
git rebase manifesto
git status
git diff
# resolve conflicts (accept incoming change)
git add manifesto.md
git rebase --continue
git checkout manifesto && git merge --ff-only paragraph-1

2. Paragraph 2 - Rebase with conflicts, keep both

git checkout paragraph-2
git rebase manifesto
git status
git diff
# resolve conflicts (keep both changes, add an empty line in between)
git add manifesto.md
git rebase --continue
git checkout manifesto && git merge --ff-only paragraph-2

3. Paragraph 3 - Three-argument rebase (--onto)

NB! Don't forget to use git log --graph --pretty=oneline <branch names> to see what's going on.

git checkout paragraph-3
git log --graph --pretty=oneline manifesto paragraph-3
# copy previous commit hash (Paragraph 1)
git diff manifesto <commit hash> # see that there's no diff
git rebase --onto manifesto <commit hash> paragraph-3
git status
git diff
# resolve conflicts (keep both changes, add an empty line in between)
git add manifesto.md
git rebase --continue
git checkout manifesto && git merge --ff-only paragraph-3

4. Formatting - interactive rebase and squashing (Careful! VIM!)

git checkout formatting
git log --graph --pretty=oneline manifesto formatting
git rebase -i manifesto
# Drop the first one (Paragraph 2), pick Formatting 1 and squash Formatting 2.
# Then `Esc :wq`
git status
git diff
# resolve conflicts
git add manifesto.md
git rebase --continue
# resolve conflicts
git add manifesto.md
git rebase --continue
git log --graph --pretty=oneline manifesto formatting
git show formatting # or commit hash
git checkout manifesto && git merge --ff-only formatting

5. Title - The way you like it (WebStorm maybe? ;)