TestGen Lite

Scan your repo, see what is testable, and install a minimal Vitest foundation.

TestGen Lite is free on GitHub.
It helps you understand your testing surface and get the runner in place.

TestGen Full is available on Gumroad for $39:
marinedep.gumroad.com/l/testgen

The public version is intentionally limited. It shows you what is testable and gets Vitest running. It does not generate the actual tests.

Quick Example

Run:

python3 scripts/scan_testable.py /path/to/repo

Example output:

Repo: my-app
Server Actions: 4
API routes: 3
Components: 12
Existing tests: 0
Largest gap: High-value application logic exists, but no test suite is present yet.

That alone tells you whether the repo is:

• basically untested
• partially covered
• worth pushing into a full test-generation workflow

Installation

Manual

Clone the repo:

git clone https://github.com/Marinou92/TestGen.git
cd TestGen

Run the scanner:

python3 scripts/scan_testable.py /path/to/your/repo

Copy the templates:

cp templates/vitest.config.ts /path/to/your/repo/vitest.config.ts
cp templates/setup.ts /path/to/your/repo/setup.ts

Install the minimum dependencies.

For npm:

npm install -D vitest @testing-library/react @testing-library/jest-dom jsdom

For pnpm:

pnpm add -D vitest @testing-library/react @testing-library/jest-dom jsdom

For yarn:

yarn add -D vitest @testing-library/react @testing-library/jest-dom jsdom

Add scripts in package.json:

{
  "scripts": {
    "test": "vitest",
    "test:watch": "vitest",
    "test:run": "vitest --run",
    "test:coverage": "vitest --coverage"
  }
}

With AI Coding Tools

This repo is not only for Codex.

SKILL.md is included for Codex-style skill workflows, but the scanner and templates are tool-agnostic.

You can use it with:

• Codex
• Claude Code
• ChatGPT coding sessions
• Cursor-style agent workflows
• manual developer setup

Example prompt:

Use this repository as guidance. Run scripts/scan_testable.py on my repo, summarize what is testable, then copy templates/vitest.config.ts and templates/setup.ts into my project without generating tests.

What TestGen Lite Includes

TestGen Lite (free — GitHub)

Feature	Description
Framework detection	Identifies Next.js, React, Vite, Express, and the router style when obvious from the codebase
Stack detection	Detects Supabase, Prisma, NextAuth, Stripe, React Query, and Zustand from dependencies and imports
Test runner detection	Checks whether Vitest, Jest, Playwright, or another runner is already present
Scan of testable targets	Counts and categorizes Server Actions, API routes, utils, components, and middleware-like files
Priority scoring	Labels target categories as high, medium, or low priority based on risk and structure
Critical path detection	Flags likely auth, payment, and CRUD flows in the codebase
Automatic Vitest setup	Ships a starter vitest.config.ts adapted for modern frontend repos
Basic mock setup	Ships a starter setup.ts with fetch, RTL, and test env defaults
Package script guidance	Gives you the scripts to add for test, test:watch, and test:coverage

What TestGen Lite Does Not Include

TestGen Lite does not:

• generate tests
• generate Server Action tests
• generate API route tests
• generate component tests
• add Playwright
• add CI workflows
• execute coverage and findings flows
• ship the internal reference files and adapters from the full version

That gap is deliberate.

Lite gives you visibility and setup. Full gives you the actual QA acceleration.

TestGen Full ($39 — Gumroad)

Get it here: marinedep.gumroad.com/l/testgen

Everything in Lite, plus:

Audit

Feature	Description
TEST-AUDIT.md	Full audit of repo layout, package manager, test stack, and recommendations
Top 5 scored targets	The 5 highest-value files or modules to test next, ranked with reasoning
Boundary mapping	Identifies system boundaries such as external APIs, DB, auth, and required mocks
Stack recommendations	Suggests the right testing stack for the project: Vitest vs Jest, MSW vs manual mocks, and more

Generation — Utilities

Feature	Description
Pure function tests	Valid input, edge cases, invalid input, and return contract coverage
Zod validator tests	Verifies schemas accept valid input and reject bad input cleanly
Custom hook tests	Uses renderHook and checks state changes plus side effects

Generation — Server Actions

Feature	Description
Auth checks	Verifies unauthenticated users are rejected and the mutation is not executed
Input validation	Verifies invalid input returns a structured error instead of crashing
Happy path	Verifies valid input plus auth executes the mutation and calls revalidation
Error handling	Verifies DB or dependency failures are caught and returned cleanly

Generation — API Route Handlers

Feature	Description
Unsupported method test	GET on a POST-only endpoint should return 405
Missing auth test	Request without session should return 401
Invalid input test	Malformed body should return 400 with a useful message
Happy path test	Valid request should return 200 with the correct payload
Error handling test	Server error should return 500 with a safe message and no stack trace

Generation — Components

Feature	Description
Form tests	Submit, client validation, loading state, and error display
Conditional rendering tests	Verifies loading, error, empty, and data branches
Data-driven component tests	Verifies behavior with mocked data and boundary conditions
Skip visual-only components	Avoids wasting time on components with no meaningful logic

Generation — E2E (optional)

Feature	Description
Playwright config	Generates a playwright.config.ts adapted to the repo
Auth flow	signup -> login -> dashboard -> logout
CRUD flow	create -> list -> edit -> delete
Payment flow	checkout -> confirmation with Stripe-aware mocking strategy

Adapters

Feature	Description
App Router (Next.js 15+)	Mocks cookies(), headers(), redirect(), notFound(), and revalidatePath()
Supabase	Mocks server and browser clients, auth.getUser(), and common query chains
NextAuth	Mocks getServerSession() and useSession()
Prisma	Mocks the Prisma client with reusable factory-style patterns
Stripe	Mocks constructEvent() for webhooks and checkout session creation
React Query	Ships patterns for useQuery and useMutation with a QueryClientProvider wrapper
Zustand	Ships isolated store mocking patterns with createStore()

Execution

Feature	Description
One-shot runner	run_full_testgen.py runs scan, audit, execute, and report in one command
Vitest execution	Runs generated tests and captures the results
Playwright execution	Runs E2E tests when requested

Diagnostic

Feature	Description
TEST_FINDINGS.md	Post-execution report with structured results
Pass/fail count	Counts what passed vs failed
Probable product bugs	Flags tests that failed because the code likely has a real bug
Infra and mock gaps	Identifies missing or misconfigured mocks and harness issues
Coverage notes	Summarizes likely coverage by category: actions, routes, utils, components

CI/CD

Feature	Description
GitHub Actions workflow	Ships a ready-to-use test.yml for PR validation

References

File	Description
unit-patterns.md	Unit-testing patterns and framework-specific examples
integration-patterns.md	API route, Server Action, and webhook testing patterns
e2e-patterns.md	Playwright patterns for hydration, auth, and navigation
test-antipatterns.md	Common AI-generated testing mistakes to avoid

Lite vs Full, In One Sentence

• Lite tells you what is testable and sets up Vitest.
• Full writes the tests, runs them, and tells you what broke.

Repo Structure

testgen/
├── SKILL.md
├── scripts/
│   └── scan_testable.py
├── templates/
│   ├── vitest.config.ts
│   └── setup.ts
├── README.md
└── LICENSE

Why This Repo Is Minimal

This repo does not pretend that:

• setup equals coverage
• counting files equals testing
• a config template equals a QA workflow

It gives you the smallest honest slice of the product.

If you want the real leverage, the full version is here:

marinedep.gumroad.com/l/testgen