Git Exercises - Practical Test

mkdir test-git && cd test-git && git init

# 3 commits
echo "print('v1')" > app.py && git add . && git commit -m "Version 1"
echo "print('v2')" > app.py && git add . && git commit -m "Version 2"
echo "print('v3 with bug')" > app.py && git add . && git commit -m "Version 3"

# Fix the last commit
echo "print('v3 fixed')" > app.py && git add . && git commit --amend -m "Version 3 - Fixed"

# Base
echo "print('main')" > main.py && git add . && git commit -m "Main app"

# Feature 1
git checkout -b feature-login
echo "print('login')" > login.py && git add . && git commit -m "Add login"

# Feature 2
git checkout main && git checkout -b feature-api
echo "print('api')" > api.py && git add . && git commit -m "Add API"

# Merge everything into main
git checkout main
git merge feature-login
git merge feature-api

# Clean up
git branch -d feature-login feature-api

mkdir test-merge && cd test-merge && git init
echo "print('base')" > app.py && git add . && git commit -m "Base"

# Feature branch
git checkout -b feature
echo "print('feature')" > feature.py && git add . && git commit -m "Add feature"

# Main moves forward
git checkout main
echo "print('base v2')" > app.py && git add . && git commit -m "Update base"

# Merge
git merge feature
git log --graph --oneline    # See the history with merge

mkdir test-rebase && cd test-rebase && git init
echo "print('base')" > app.py && git add . && git commit -m "Base"

git checkout -b feature
echo "print('feature')" > feature.py && git add . && git commit -m "Add feature"

git checkout main
echo "print('base v2')" > app.py && git add . && git commit -m "Update base"

# Rebase
git checkout feature && git rebase main
git checkout main && git merge feature
git log --oneline           # Linear history

mkdir test-stash && cd test-stash && git init
echo "print('v1')" > app.py && git add . && git commit -m "Version 1"

# You start coding
echo "print('work in progress')" >> app.py

# EMERGENCY! You have to switch
git stash                    # Save
git checkout -b hotfix
echo "print('URGENT FIX')" > fix.py && git add . && git commit -m "Critical fix"

# Cherry-pick the fix onto main
git checkout main
git cherry-pick <hash-du-fix>

# Go back to your work
git stash pop
echo "print('feature complete')" >> app.py && git add . && git commit -m "Feature done"

mkdir test-urgence && cd test-urgence && git init

# Several commits
echo "print('v1')" > app.py && git add . && git commit -m "Version 1"
echo "print('v2')" > app.py && git add . && git commit -m "Version 2"
echo "print('v3')" > app.py && git add . && git commit -m "Version 3"
echo "print('v4 BROKEN')" > app.py && git add . && git commit -m "Version 4 - Bug!"

# Oh no! v4 breaks everything in production
git log --oneline                    # Note the v3 hash

# Solution 1: Hard reset (destructive)
git reset --hard <hash-v3>           # Back to v3, v4 disappears
git log --oneline                    # Only 3 commits left

# Solution 2: Revert (safe)
# Put v4 back first
git reset --hard <hash-v4>           # Go back to v4
git revert HEAD                      # Create a commit that undoes v4
git log --oneline                    # 5 commits: v1,v2,v3,v4,revert-v4