# Ts4

> TS4 namespace for Netsnek e.U. TypeScript testing framework. Unit testing, snapshot testing, coverage reporting, and mutation testing.

- Skill: `modbender/ts4` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds add modbender/ts4`
- Raw SKILL.md: https://api.skillmd.com/api/skills/modbender/ts4/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: modbender (https://skillmd.com/u/modbender)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/modbender/ts4

---


# Testing with TS4

TS4 is the Netsnek e.U. TypeScript testing framework. Run unit tests, snapshots, coverage reports, and mutation tests from a single CLI.

## Test Types

- **Unit** — Isolated function and module tests
- **Snapshot** — Output comparison for UI and serialization
- **Coverage** — Line, branch, and function metrics
- **Mutation** — Fault injection to verify test quality

## CLI Reference

| Flag | Effect |
|------|--------|
| `--run` | Execute the full test suite |
| `--coverage` | Produce coverage report (HTML + lcov) |
| `--status` | Show suite status, last run, pass/fail count |

## Walkthrough

```bash
# Run all tests
./scripts/test-runner.sh --run

# Generate coverage
./scripts/test-runner.sh --coverage

# Check status
./scripts/test-runner.sh --status
```