impacted

It takes a list of changed files, builds a dependency graph from your test files by statically analyzing their imports, and returns only the test files that depend on the changed files.

A userland implementation of predictive test selection for Node.js test runner.

Usage

# Run only impacted tests (--since gets changed files from git diff)
node --test $(npx impacted --since main)

# Pipe changed files from stdin
node --test $(git diff --name-only main | npx impacted)

# Works with any test runner
vitest $(npx impacted --since main)
jest $(npx impacted --since main)

# Custom test pattern
npx impacted --since main -p "src/**/*.spec.js"

# Multiple patterns
npx impacted --since main -p "test/**/*.test.js" -p "test/**/*.spec.js"

GitHub Action

- uses: actions/checkout@v4
  with:
    fetch-depth: 0

- uses: sozua/impacted@v1
  id: impacted
  with:
    pattern: '**/*.{test,spec}.{js,mjs,cjs,jsx,ts,mts,cts,tsx}'  # default

- name: Run impacted tests
  if: steps.impacted.outputs.has-impacted == 'true'
  run: node --test ${{ steps.impacted.outputs.files }}

See action.yml for all inputs and outputs.

Programmatic API

import { findImpacted } from 'impacted';

const tests = await findImpacted({
  changedFiles: ['src/utils.js'],
  testFiles: 'test/**/*.test.js',
  cacheFile: '.impacted-cache.json', // optional
});

node:test run() integration

import { run } from 'node:test';
import { findImpacted } from 'impacted';

const files = await findImpacted({
  changedFiles: ['src/utils.js'],
  testFiles: 'test/**/*.test.js',
});

run({ files });

See examples/05-node-test-run for a full working example.

TypeScript

TypeScript files (.ts, .mts, .cts, .tsx) are supported out of the box on Node.js >= 22.7. Type stripping is handled via node:module.stripTypeScriptTypes() — no additional dependencies required.

Follows Node.js core's TypeScript philosophy: explicit extensions, no tsconfig.json, no path aliases.

Limitations

• Static analysis only — dynamic require(variable) not supported
• Local files only — node_modules changes won't trigger tests
• TypeScript support requires Node.js >= 22.7 (JS analysis works on Node.js >= 18)

Requirements

• Node.js >= 18 (TypeScript support requires >= 22.7)

License

MIT