Registry / testing / babel-plugin-tester

babel-plugin-tester

library12.0.0jsnpmunverified

Utilities for writing tests for Babel plugins and presets. Version 12.0.0 is current. The library supports Jest, Mocha, Jasmine, node:test, and Vitest. Key differentiators: automatic fixture file loading, built-in prettier formatting, snapshot-based testing, environment variable filtering (TEST_ONLY, TEST_SKIP), and async ResultFormatter. Breaking changes in v12 include dropping default exports, requiring Node.js >=20.18.0, and adopting prettier@3's async interface. Peer dependency on @babel/core >=7.22.0.

testing

npm install babel-plugin-tester

github ↗package ↗

INSTALL

IMPORT

SIG · BABEL-PLUGIN-TESTE

babel-plugin-tester

testingjavascriptv12.0.0

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

pluginTester

✓ import { pluginTester } from 'babel-plugin-tester'

✗ import pluginTester from 'babel-plugin-tester'

Default export was removed in v12. Use named import only.

prettierFormatter

✓ import { prettierFormatter } from 'babel-plugin-tester'

Available as a named export; commonly used to format output with Prettier.

pluginTester (CJS)

✓ const { pluginTester } = require('babel-plugin-tester')

✗ const pluginTester = require('babel-plugin-tester')

CJS require must destructure the named export. Default require returns an object with named exports.

Basic test suite for a Babel plugin with inline code tests and a snapshot test.

import { pluginTester } from 'babel-plugin-tester'; import myPlugin from './my-plugin'; pluginTester({ plugin: myPlugin, tests: { 'transforms correctly': { code: 'const x = 1;', output: 'const x = 1;', }, 'snapshot test': { code: 'const y = 2;', snapshot: true, }, }, });

Debug

Known issues

breakingDefault export removed in v12. Import { pluginTester } instead of default import.

fix

Change `import pluginTester from 'babel-plugin-tester'` to `import { pluginTester } from 'babel-plugin-tester'`.

affects: >=12.0.0

breakingMinimum Node.js version is now 20.18.0 (v12).

fix

Upgrade Node.js to >=20.18.0.

affects: >=12.0.0

breakingResultFormatter is now async (returns Promise) due to prettier@3.

fix

If using custom formatter, ensure it returns a Promise or use async/await.

affects: >=12.0.0

gotchaWith prettier@3, some Node versions require --experimental-vm-modules flag.

fix

Run tests with `NODE_OPTIONS='--no-warnings --experimental-vm-modules' npx jest`.

affects: >=12.0.0

breakingImplicit global option merging removed in v11. All options must be explicitly set per test or via global config.

fix

Move shared options to the top-level pluginTester configuration.

affects: >=11.0.0 <12.0.0

Errors

Common errors & fixes

TypeError: pluginTester is not a function

Using default import with v12+ which removed default export.

fix

Change to named import: `import { pluginTester } from 'babel-plugin-tester'`

Error: Cannot find module 'babel-plugin-tester'

Missing install or wrong import path.

fix

Run `npm install --save-dev babel-plugin-tester` and ensure import path is correct.

AssertionError: expected 'const x = 1;' to equal 'const x = 2;'

Test output mismatch; plugin may not be transforming as expected.

fix

Check plugin logic and verify test input/output.

Upgrade

Version history

12.0.0latest on npm

Audit

Dependencies

@babel/corerequiredRequired peer dependency for transforming code with Babel plugins/presets.

Agent activity

20 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/babel-utils/babel-plugin-tester ↗

packagehttps://www.npmjs.com/package/babel-plugin-tester ↗