tailtest -- AI software testing for Claude Code
You build. Claude builds. tailtest makes sure it works.
tailtest is the open-source AI software testing layer for Claude Code. It runs inside the build loop: every time Claude edits a file, tailtest queues the file, generates production-shaped scenarios using the R1-R15 rule layer, runs them with your existing test runner (pytest, jest, go test, etc.), and surfaces failures back to Claude within the same turn. Hook-based. Deterministic. No prompting required.
Open source (MIT), no telemetry, no SaaS account. Includes adversarial mode (R15) that biases scenario generation toward 8 breakage categories -- the mode we've used to find 16 real bugs across 47 open-source Python repositories.
Read more on tailtest.com · Platform overview · Agent-edit testing deep dive · Full docs
Install
claude plugin marketplace add avansaber/tailtest
claude plugin install tailtest@avansaber-tailtest
Restart Claude Code after install. No other setup required.
Update
claude plugin marketplace update avansaber-tailtest
claude plugin update tailtest@avansaber-tailtest
Uninstall
claude plugin remove tailtest@avansaber-tailtest
How it works
After any Claude-written file lands in your project:
- tailtest generates scenarios that describe real business behavior -- not function signatures
- It runs them using your existing test runner (pytest, vitest, jest, go test, and more)
- Pass:
tailtest: N scenarios -- all passed. Fail: one line surfaced, "want me to fix this?"
Supported languages
Python, TypeScript, JavaScript, Go, Ruby, PHP, Java, Kotlin, C#, Rust
Runners are auto-detected from pyproject.toml, package.json, go.mod, build.gradle.kts, *.csproj, *.sln, and other standard manifests.
Quick config
Create .tailtest/config.json in your project root to control depth:
{ "depth": "standard" }
Options: simple (2-3 scenarios), standard (5-8, default), thorough (10-15).
See tailtest.com/docs/config for all options.
Other tailtest variants
Same R1-R15 rule layer, same adversarial test mode, different host integration. This repo is the Claude Code variant.
See tailtest.com/demo/claude-code for a live walkthrough of this variant, or tailtest.com/comparison for a feature matrix across all four.
License
MIT
