Test Gen

Your code has 12% test coverage and your manager is asking questions. This tool generates unit tests from your source files. Covers happy paths, edge cases, error conditions. Tests that actually test something, not just exist for coverage numbers.

One command. Zero config. Just works.

Quick Start

npx ai-test-gen ./src/utils.ts

What It Does

Generates unit tests for your functions and classes
Covers happy path, edge cases, and error conditions
Creates tests for Jest, Vitest, or Mocha
Mocks dependencies automatically
Includes meaningful assertions, not just "expect(true).toBe(true)"

Usage Examples

# Generate tests for a single file
npx ai-test-gen ./src/auth.ts

# Generate for all files in a directory
npx ai-test-gen ./src/services/

# Specify test framework
npx ai-test-gen ./src/utils.ts --framework vitest

# Output to a specific location
npx ai-test-gen ./src/parser.ts --output ./tests/parser.test.ts

Best Practices

Review generated tests - AI tests are a starting point, not a finish line
Run them immediately - Catch issues while context is fresh
Add your own edge cases - You know your domain better than AI
Don't trust coverage alone - Good tests test behavior, not lines

When to Use This

Inheriting a codebase with no tests
Adding tests to a new feature quickly
Hitting a coverage target for CI
Learning what good tests look like for your code

Part of the LXGIC Dev Toolkit

This is one of 110+ free developer tools built by LXGIC Studios. No paywalls, no sign-ups, no API keys on free tiers. Just tools that work.

Find more:

GitHub: https://github.com/LXGIC-Studios
Twitter: https://x.com/lxgicstudios
Substack: https://lxgicstudios.substack.com
Website: https://lxgicstudios.com

Requirements

No install needed. Just run with npx. Node.js 18+ recommended.

npx ai-test-gen --help

How It Works

The tool parses your source file, identifies testable units (functions, classes, methods), analyzes their signatures and implementations, then generates test cases that cover normal operation, edge cases, and error handling.

License

MIT. Free forever. Use it however you want.

Built by LXGIC Studios

GitHub: github.com/lxgicstudios/test-gen
Twitter: @lxgicstudios