git-bisect-auto

name	git-bisect-auto
description	Automated git bisect to find the exact commit that introduced a bug. Run a test command against each bisect step, report the first bad commit with full context.
category	development
maturity	stable
tags	["git-bisect","regression-finding","binary-search","test-runner","regression-report"]

git-bisect-auto

Automated git bisect to find the exact commit that introduced a bug. Run a test command against each bisect step, report the first bad commit with full context.

When to Use

• A regression was introduced and you need to find which commit caused it
• Narrowing down bug introductions in large commit ranges
• Automating binary search through git history
• Generating regression reports for issues/PRs

Scripts

auto-bisect.sh

Automated git bisect runner with safety features.

# Find which commit broke the tests
bash scripts/auto-bisect.sh --good v1.0 --bad HEAD --test "npm test"

# Find which commit introduced a file
bash scripts/auto-bisect.sh --good abc123 --bad def456 --test "test ! -f bug.txt"

# Find which commit broke compilation
bash scripts/auto-bisect.sh --good main~20 --bad main --test "make build"

Features:

• Stashes uncommitted changes before starting, restores after
• Runs git bisect start, sets good/bad, then git bisect run
• After completion: shows first bad commit, author, date, message, diff stats, changed files
• Cleans up bisect state even on failure

Test command convention: Exit 0 = good (no bug), exit non-zero = bad (bug present). Exit 125 = skip (untestable commit).

bisect-test-gen.sh

Generate ready-to-use test scripts for common bisect scenarios.

# Does it compile?
bash scripts/bisect-test-gen.sh --type compile --params "make build"

# Does a specific test pass?
bash scripts/bisect-test-gen.sh --type test --params "pytest tests/test_auth.py"

# Does the server start (and respond)?
bash scripts/bisect-test-gen.sh --type server --params "npm start,http://localhost:3000,5"

# Does a URL return 200?
bash scripts/bisect-test-gen.sh --type http --params "http://localhost:3000/api/health"

# Does output contain/not contain a string?
bash scripts/bisect-test-gen.sh --type grep --params "npm run build,error,invert"

Output: executable test script written to bisect-test.sh.

regression-report.sh

Generate a detailed regression report for the bad commit.

# Generate report for a commit
bash scripts/regression-report.sh abc123def

# With repo context
bash scripts/regression-report.sh abc123def --repo /path/to/repo

Output: Markdown report with commit info, full diff, files changed, author, related commits by same author. Ready for issue/PR description.

References

• references/bisect-strategies.md — When to use bisect, preparing tests, handling flaky tests, merge commits, skipping commits