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

``bash


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

`yaml
- 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

`javascript
import { findImpacted } from 'impacted';

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

$3

`javascript
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