Lawest NPM | npm.io

lawest

A blazing fast test runner powered by Vite.

Features

Vite's transformer, resolver, and plugin system. Powered by vite-node.
Jest Snapshot.
Chai for assertions.
Async suite / test.
ESM friendly, top level await.
Suite and Test filtering (skip, only, todo).

import { assert, describe, expect, it } from 'lawest'

describe('suite name', () => {
  it('foo', () => {
    assert.equal(Math.sqrt(4), 2)
  })

  it('bar', () => {
    expect(1 + 1).eq(2)
  })

  it('snapshot', () => {
    expect({ foo: 'bar' }).toMatchSnapshot()
  })
})

$ npx lawest

Global APIs

By default, lawest does not provide global APIs for explicitness. If you prefer to use the APIs globally like Jest, you can pass the --global option to CLI or add global: true in the config.

// vite.config.ts
import { defineConfig } from 'vite'
export default defineConfig({
  test: {
    global: true,
  },
})

To get TypeScript working with the global APIs, add lawest/global to the types filed in your tsconfig.json

// tsconfig.json
{
  "compilerOptions": {
    "types": [
      "lawest/global"
    ]
  }
}

Filtering

Skipping suites and tasks

Use .skip to avoid running certain suites or tests

describe.skip('skipped suite', () => {
  it('task', () => {
    // Suite skipped, no error
    assert.equal(Math.sqrt(4), 3)
  })
})
describe('suite', () => {
  it.skip('skipped task', () => {
    // Task skipped, no error
    assert.equal(Math.sqrt(4), 3)
  })
})

Selecting suites and tests to run

Use .only to only run certain suites or tests

// Only this suite (and others marked with only) are run
describe.only('suite', () => {
  it('task', () => {
    assert.equal(Math.sqrt(4), 3)
  })
})
describe('another suite', () => {
  it('skipped task', () => {
    // Task skipped, as tests are running in Only mode
    assert.equal(Math.sqrt(4), 3)
  })
  it.only('task', () => {
    // Only this task (and others marked with only) are run
    assert.equal(Math.sqrt(4), 2)
  })
})

Unimplemented suites and tests

Use .todo to stub suites and tests that should be implemented

// An entry will be shown in the report for this suite
describe.todo('unimplemented suite')
// An entry will be shown in the report for this task
describe.suite('suite', () => {
  it.todo('unimplemented task')
})