feat: add module 7 on rebasing

module-07-rebasing/README.md

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+# Module 07: Rebasing
+
+## Learning Objectives
+
+By the end of this module, you will:
+- Understand what rebasing is and how it works
+- Know the difference between merge and rebase
+- Perform a rebase to integrate changes from one branch to another
+- Understand when to use rebase vs merge
+- Know the golden rule of rebasing
+
+## Challenge Description
+
+You have a repository with a `main` branch and a `feature` branch. While you were working on the feature branch, new commits were added to `main`. You want to incorporate those changes into your feature branch while maintaining a clean, linear history.
+
+Your task is to:
+1. Review the current commit history
+2. Rebase the `feature` branch onto `main`
+3. Verify that the history is now linear
+
+## Key Concepts
+
+### What is Rebasing?
+
+Rebasing is the process of moving or combining a sequence of commits to a new base commit. Instead of creating a merge commit like `git merge` does, rebasing rewrites the commit history by replaying your commits on top of another branch.
+
+### Rebase vs Merge
+
+**Merge:**
+```
+    A---B---C feature
+   /         \
+  D---E---F---G main
+```
+Creates a merge commit (G) that ties the histories together.
+
+**Rebase:**
+```
+              A'--B'--C' feature
+             /
+  D---E---F main
+```
+Replays commits A, B, C on top of F, creating new commits A', B', C' with the same changes but different commit hashes.
+
+### Benefits of Rebasing
+
+- **Cleaner history**: Linear history is easier to read and understand
+- **Simpler log**: No merge commits cluttering the history
+- **Easier bisecting**: Finding bugs with `git bisect` is simpler with linear history
+
+### The Golden Rule of Rebasing
+
+**Never rebase commits that have been pushed to a public/shared repository.**
+
+Why? Because rebasing rewrites history by creating new commits. If others have based work on the original commits, rebasing will cause serious problems for collaborators.
+
+**Safe to rebase:**
+- Local commits not yet pushed
+- Feature branches you're working on alone
+- Cleaning up your work before creating a pull request
+
+**Never rebase:**
+- Commits already pushed to a shared branch (like `main` or `develop`)
+- Commits that others might have based work on
+
+## Useful Commands
+
+```bash
+# Rebase current branch onto another branch
+git rebase <branch-name>
+
+# View commit history as a graph
+git log --oneline --graph --all
+
+# If conflicts occur during rebase:
+# 1. Resolve conflicts in files
+# 2. Stage the resolved files
+git add <file>
+# 3. Continue the rebase
+git rebase --continue
+
+# Abort a rebase if something goes wrong
+git rebase --abort
+
+# Check which branch you're on
+git branch
+
+# Switch to a branch
+git checkout <branch-name>
+```
+
+## Verification
+
+Run the verification script to check your solution:
+
+```bash
+.\verify.ps1
+```
+
+The verification will check that:
+- You're on the feature branch
+- The rebase was completed successfully
+- The history is linear (no merge commits)
+- All commits from both branches are present
+
+## Tips
+
+- Always check your commit graph with `git log --oneline --graph --all` before and after rebasing
+- If you encounter conflicts during rebase, resolve them just like merge conflicts
+- Use `git rebase --abort` if you want to cancel the rebase and start over
+- Rebasing rewrites history, so the commit hashes will change
+- Only rebase local commits that haven't been shared with others
+
+## When to Use Rebase vs Merge
+
+**Use Rebase when:**
+- You want a clean, linear history
+- Working on a local feature branch that hasn't been shared
+- Updating your feature branch with the latest changes from main
+- You want to clean up commits before submitting a pull request
+
+**Use Merge when:**
+- Working on a shared/public branch
+- You want to preserve the complete history including when branches diverged
+- You're merging a completed feature into main
+- You want to be safe and avoid rewriting history
+
+## What You'll Learn
+
+Rebasing is a powerful tool for maintaining a clean project history. While merging is safer and preserves exact history, rebasing creates a more readable linear timeline. Understanding both techniques and knowing when to use each is essential for effective Git workflow management.

module-07-rebasing/reset.ps1

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+#!/usr/bin/env pwsh
+
+<#
+.SYNOPSIS
+    Resets the rebasing challenge environment.
+
+.DESCRIPTION
+    Removes the existing challenge directory and runs setup.ps1
+    to create a fresh challenge environment.
+#>
+
+Write-Host "Resetting challenge environment..." -ForegroundColor Yellow
+
+# Remove existing challenge directory if present
+if (Test-Path "challenge") {
+    Remove-Item -Path "challenge" -Recurse -Force
+    Write-Host "Removed existing challenge directory." -ForegroundColor Cyan
+}
+
+# Run setup script
+Write-Host "Running setup script...`n" -ForegroundColor Cyan
+& ".\setup.ps1"

module-07-rebasing/setup.ps1

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+#!/usr/bin/env pwsh
+
+<#
+.SYNOPSIS
+    Sets up the rebasing challenge environment.
+
+.DESCRIPTION
+    Creates a Git repository with diverged branches to practice rebasing.
+    The feature branch needs to be rebased onto main.
+#>
+
+# Remove existing challenge directory if present
+if (Test-Path "challenge") {
+    Write-Host "Removing existing challenge directory..." -ForegroundColor Yellow
+    Remove-Item -Path "challenge" -Recurse -Force
+}
+
+# Create challenge directory
+Write-Host "Creating challenge environment..." -ForegroundColor Cyan
+New-Item -ItemType Directory -Path "challenge" | Out-Null
+Set-Location "challenge"
+
+# Initialize git repository
+git init | Out-Null
+git config user.name "Workshop User" | Out-Null
+git config user.email "user@workshop.local" | Out-Null
+
+# Create initial file and commit
+$readme = @"
+# My Project
+
+A sample project for learning Git rebasing.
+"@
+
+Set-Content -Path "README.md" -Value $readme
+git add README.md
+git commit -m "Initial commit" | Out-Null
+
+# Create and switch to feature branch
+git checkout -b feature | Out-Null
+
+# Add commits on feature branch
+$feature1 = @"
+# My Project
+
+A sample project for learning Git rebasing.
+
+## Features
+
+- Feature A: User authentication
+"@
+
+Set-Content -Path "README.md" -Value $feature1
+git add README.md
+git commit -m "Add feature A" | Out-Null
+
+$feature2 = @"
+# My Project
+
+A sample project for learning Git rebasing.
+
+## Features
+
+- Feature A: User authentication
+- Feature B: Data validation
+"@
+
+Set-Content -Path "README.md" -Value $feature2
+git add README.md
+git commit -m "Add feature B" | Out-Null
+
+# Switch back to main and add commits (simulating other work happening on main)
+git checkout main | Out-Null
+
+$main1 = @"
+# My Project
+
+A sample project for learning Git rebasing.
+
+## Installation
+
+Run \`npm install\` to install dependencies.
+"@
+
+Set-Content -Path "README.md" -Value $main1
+git add README.md
+git commit -m "Add installation instructions" | Out-Null
+
+$main2 = @"
+# My Project
+
+A sample project for learning Git rebasing.
+
+## Installation
+
+Run \`npm install\` to install dependencies.
+
+## Configuration
+
+Copy \`config.example.json\` to \`config.json\` and update settings.
+"@
+
+Set-Content -Path "README.md" -Value $main2
+git add README.md
+git commit -m "Add configuration instructions" | Out-Null
+
+# Switch back to feature branch
+git checkout feature | Out-Null
+
+# Return to module directory
+Set-Location ..
+
+Write-Host "`n========================================" -ForegroundColor Green
+Write-Host "Challenge environment created!" -ForegroundColor Green
+Write-Host "========================================" -ForegroundColor Green
+Write-Host "`nYou are now on the 'feature' branch." -ForegroundColor Cyan
+Write-Host "The 'main' branch has new commits that aren't in your feature branch." -ForegroundColor Cyan
+Write-Host "`nYour task:" -ForegroundColor Yellow
+Write-Host "1. Navigate to the challenge directory: cd challenge" -ForegroundColor White
+Write-Host "2. View the commit history: git log --oneline --graph --all" -ForegroundColor White
+Write-Host "3. Rebase the 'feature' branch onto 'main'" -ForegroundColor White
+Write-Host "4. View the history again to see the linear result" -ForegroundColor White
+Write-Host "`nRun '../verify.ps1' from the challenge directory to check your solution.`n" -ForegroundColor Cyan

module-07-rebasing/verify.ps1

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+#!/usr/bin/env pwsh
+
+<#
+.SYNOPSIS
+    Verifies the rebasing challenge solution.
+
+.DESCRIPTION
+    Checks that the user successfully rebased the feature branch onto main,
+    resulting in a clean, linear history.
+#>
+
+Set-Location "challenge" -ErrorAction SilentlyContinue
+
+# Check if challenge directory exists
+if (-not (Test-Path "../verify.ps1")) {
+    Write-Host "Error: Please run this script from the module directory" -ForegroundColor Red
+    exit 1
+}
+
+if (-not (Test-Path ".")) {
+    Write-Host "Error: Challenge directory not found. Run setup.ps1 first." -ForegroundColor Red
+    Set-Location ..
+    exit 1
+}
+
+Write-Host "Verifying your solution..." -ForegroundColor Cyan
+
+# Check if git repository exists
+if (-not (Test-Path ".git")) {
+    Write-Host "[FAIL] No git repository found." -ForegroundColor Red
+    Set-Location ..
+    exit 1
+}
+
+# Check current branch
+$currentBranch = git branch --show-current 2>$null
+if ($currentBranch -ne "feature") {
+    Write-Host "[FAIL] You should be on the 'feature' branch." -ForegroundColor Red
+    Write-Host "Current branch: $currentBranch" -ForegroundColor Yellow
+    Write-Host "Hint: Use 'git checkout feature' to switch to feature branch" -ForegroundColor Yellow
+    Set-Location ..
+    exit 1
+}
+
+# Check if there's an ongoing rebase
+if (Test-Path ".git/rebase-merge") {
+    Write-Host "[FAIL] Rebase is not complete. There may be unresolved conflicts." -ForegroundColor Red
+    Write-Host "Hint: Resolve any conflicts, then use:" -ForegroundColor Yellow
+    Write-Host "  git add <file>" -ForegroundColor White
+    Write-Host "  git rebase --continue" -ForegroundColor White
+    Write-Host "Or abort with: git rebase --abort" -ForegroundColor White
+    Set-Location ..
+    exit 1
+}
+
+# Get all commits on feature branch
+$featureCommits = git log --oneline feature 2>$null
+if (-not $featureCommits) {
+    Write-Host "[FAIL] No commits found on feature branch." -ForegroundColor Red
+    Set-Location ..
+    exit 1
+}
+
+# Check commit count (should be 5: 1 initial + 2 main + 2 feature)
+$commitCount = (git rev-list --count feature 2>$null)
+if ($commitCount -ne 5) {
+    Write-Host "[FAIL] Expected 5 commits on feature branch, found $commitCount" -ForegroundColor Red
+    Write-Host "Hint: The rebased feature branch should contain:" -ForegroundColor Yellow
+    Write-Host "  - 1 initial commit" -ForegroundColor White
+    Write-Host "  - 2 commits from main" -ForegroundColor White
+    Write-Host "  - 2 commits from feature" -ForegroundColor White
+    Set-Location ..
+    exit 1
+}
+
+# Get commit messages in reverse chronological order (newest first)
+$commits = git log --pretty=format:"%s" feature 2>$null
+
+# Convert to array and reverse to get chronological order (oldest first)
+$commitArray = $commits -split "`n"
+[array]::Reverse($commitArray)
+
+# Check that commits are in the expected order after rebase
+$expectedOrder = @(
+    "Initial commit",
+    "Add installation instructions",
+    "Add configuration instructions",
+    "Add feature A",
+    "Add feature B"
+)
+
+$orderCorrect = $true
+for ($i = 0; $i -lt $expectedOrder.Length; $i++) {
+    if ($commitArray[$i] -ne $expectedOrder[$i]) {
+        $orderCorrect = $false
+        break
+    }
+}
+
+if (-not $orderCorrect) {
+    Write-Host "[FAIL] Commit order is incorrect after rebase." -ForegroundColor Red
+    Write-Host "Expected order (oldest to newest):" -ForegroundColor Yellow
+    $expectedOrder | ForEach-Object { Write-Host "  $_" -ForegroundColor White }
+    Write-Host "`nActual order:" -ForegroundColor Yellow
+    $commitArray | ForEach-Object { Write-Host "  $_" -ForegroundColor White }
+    Write-Host "`nHint: The feature commits should come AFTER the main commits" -ForegroundColor Yellow
+    Set-Location ..
+    exit 1
+}
+
+# Check that main branch still has only 3 commits (initial + 2 main commits)
+$mainCommitCount = (git rev-list --count main 2>$null)
+if ($mainCommitCount -ne 3) {
+    Write-Host "[FAIL] Main branch should have 3 commits, found $mainCommitCount" -ForegroundColor Red
+    Write-Host "Hint: You should rebase feature onto main, not the other way around" -ForegroundColor Yellow
+    Set-Location ..
+    exit 1
+}
+
+# Check that there are no merge commits (parent count should be 1 for all commits)
+$mergeCommits = git log --merges --oneline feature 2>$null
+if ($mergeCommits) {
+    Write-Host "[FAIL] Found merge commits in history. Rebasing should create a linear history." -ForegroundColor Red
+    Write-Host "Hint: Use 'git rebase main' instead of 'git merge main'" -ForegroundColor Yellow
+    Set-Location ..
+    exit 1
+}
+
+# Verify that feature branch contains all commits from main
+$mainCommits = git log --pretty=format:"%s" main 2>$null
+$featureCommitMessages = git log --pretty=format:"%s" feature 2>$null
+
+foreach ($mainCommit in ($mainCommits -split "`n")) {
+    if ($featureCommitMessages -notcontains $mainCommit) {
+        Write-Host "[FAIL] Feature branch is missing commits from main." -ForegroundColor Red
+        Write-Host "Missing: $mainCommit" -ForegroundColor Yellow
+        Set-Location ..
+        exit 1
+    }
+}
+
+# Success!
+Write-Host "`n========================================" -ForegroundColor Green
+Write-Host "SUCCESS! Challenge completed!" -ForegroundColor Green
+Write-Host "========================================" -ForegroundColor Green
+Write-Host "`nYou have successfully:" -ForegroundColor Cyan
+Write-Host "- Rebased the feature branch onto main" -ForegroundColor White
+Write-Host "- Created a clean, linear commit history" -ForegroundColor White
+Write-Host "- Preserved all commits from both branches" -ForegroundColor White
+Write-Host "`nYour feature branch now has a linear history!" -ForegroundColor Green
+Write-Host "Run 'git log --oneline --graph --all' to see the result.`n" -ForegroundColor Cyan
+
+Set-Location ..
+exit 0