APSRT

Automated Property-based Snapshot Regression Testing

APSRT is a TypeScript tool for automated regression testing. It analyzes exported functions, generates property-based input samples from their types, and snapshots the results through Vitest.

Usage

Install APSRT in the project you want to test:

npm install --save-dev @patrikelfstrom/apsrt

Or run it without adding it to package.json:

npx @patrikelfstrom/apsrt

By default it will use your local tsconfig.json.

# Use a specific tsconfig file
npx apsrt --tsconfig tsconfig.app.json

# Update snapshots
npx apsrt --update

# Watch for changes and re-run tests
npx apsrt --watch

Snapshots are stored in .apsrt/__snapshots__/runtime.test.js.snap inside the project you run APSRT from.

If APSRT detects a likely nondeterministic function such as one using Math.random(), it will stop and ask you to add an @apsrt-ignore annotation to that export.

Developer

Clone the repository and install dependencies:

git clone [email protected]:PatrikElfstrom/apsrt.git
cd apsrt
npm install

Common development commands:

npm run build
npm test
npm run typecheck

Features

• Generates runtime snapshot tests for exported TypeScript functions
• Uses fast-check to create deterministic sample inputs
• Uses Vitest snapshots to detect regressions
• Uses ts-morph and the TypeScript compiler to inspect function signatures

How it works

1. APSRT loads a TypeScript config file from the current working directory.
2. It analyzes included .ts files and finds exported functions.
3. It creates input arbitraries based on parameter type text.
4. It runs each exported function with deterministic samples.
5. It snapshots the collected input/output pairs.

Project Structure

• src/ - CLI entry, packaged runtime entry, and core implementation
• src/core/ - Type analysis, arbitrary creation, cache, and config loading
• test/unit/ - Direct unit tests for core modules
• test/integration/ - Fixture-based runtime flow coverage
• test/fixtures/ - Sample exported functions used as test inputs

Environment Variables

• APSRT_TSCONFIG: overrides the TypeScript config file name to load
• APSRT_ENABLE_CACHE=false: disables the on-disk analysis cache

Tech Stack

• TypeScript
• fast-check
• Vitest
• ts-morph

License

MIT