Bits of .NET

🐛 Binary Search Through Git History

Bug appeared sometime. Which commit? Git bisect does binary search through commits. Find the culprit in O(log n) steps.

🔧 Basic Bisect Workflow

# Start bisect
git bisect start

# Mark current commit as bad (bug exists)
git bisect bad

# Mark a known good commit (no bug)
git bisect good v1.0.0

# Git checks out middle commit
# Test the commit
# Mark as good or bad

git bisect good   # if no bug
git bisect bad    # if bug exists

# Repeat until culprit found
# Git shows the commit that introduced the bug

# End bisect session
git bisect reset

📦 Automated Bisect with Script

# Create test script that returns 0 for good, non-0 for bad
git bisect start HEAD v1.0.0
git bisect run npm test

# Or with custom script
git bisect run ./test.sh

# Example test.sh:
#!/bin/bash
npm run build
npm run test:integration
exit $?

✅ Advanced Commands

• git bisect visualize → See commits with gitk
• git bisect log → Show bisect history
• git bisect terms → Customize ‘bad’/’good’ terms
• git bisect skip → Skip current commit (if untestable)
• git bisect reset → End session and return to original HEAD

💡 Tips

• Start with wide range (commit from last week vs last month)
• Write a simple test script for automation
• Use with CI to find regression automatically
• Document culprit commits in commit message
• Combine with git blame to see who wrote it