babel-helper-transform-fixture-test-runner

6.26.2 verified Sat Apr 25 auth: no javascript maintenance

Internal Babel helper that provides a test runner for fixture-based tests within Babel's own monorepo. It is used in conjunction with babel-helper-fixtures to run transformation tests on a set of input/output fixtures. Current stable version is 6.26.2 (an older Babel 6 era package). Release cadence is tied to Babel releases. This package is not intended for direct use by consumers; it's an internal dependency for Babel development. Key differentiator: it is specific to Babel's test infrastructure and not a general-purpose testing utility.

Common errors

error Error: Cannot find module 'babel-helper-transform-fixture-test-runner' ↓

cause Package not installed or missing from node_modules. This package is an internal Babel dependency and not published to npm for general use.

fix

Install from npm: npm install babel-helper-transform-fixture-test-runner --save-dev, or switch to the scoped @babel/helper-transform-fixture-test-runner if using Babel 7+.

error TypeError: run is not a function ↓

cause Attempting to use the package without proper import or require. The exported value may be an object with a 'run' method.

fix

Use: const { run } = require('babel-helper-transform-fixture-test-runner');

Warnings

deprecated This package is part of Babel 6 and may not receive updates. Babel 7+ uses @babel/helper-transform-fixture-test-runner. ↓

fix Upgrade to the scoped @babel/helper-transform-fixture-test-runner package if using Babel 7+.

breaking In Babel 8, the package may be removed or renamed. Do not rely on this package for production code. ↓

fix Use Babel's official testing utilities like @babel/helper-plugin-test-runner instead.

gotcha The package expects fixtures in a specific directory structure. Incorrect fixture layout will cause silent failures or no tests run. ↓

fix Follow Babel's fixture convention: input.js and output.js in a test case folder. Refer to Babel's own test fixtures for examples.

Install

npm install babel-helper-transform-fixture-test-runner

yarn add babel-helper-transform-fixture-test-runner

pnpm add babel-helper-transform-fixture-test-runner

Imports

default
wrong
```
const run = require('babel-helper-transform-fixture-test-runner')
```
correct
```
import run from 'babel-helper-transform-fixture-test-runner'
```
This is an internal Babel package. In Babel 6 era, it likely uses CommonJS. For Babel 7+, this package may be scoped under @babel/helper-transform-fixture-test-runner.
run
wrong
```
import run from 'babel-helper-transform-fixture-test-runner'
```
correct
```
const run = require('babel-helper-transform-fixture-test-runner')
```
Since this package is typically used in Node.js test environments, CommonJS require is common. ESM imports may not work due to lack of ESM exports.

run

wrong

const run = require('babel-helper-transform-fixture-test-runner').run

correct

const { run } = require('babel-helper-transform-fixture-test-runner')

If the package exports a named function 'run', destructuring is preferred. The exact export pattern may vary by version.

Quickstart

Demonstrates how to use the runner with a fixture directory and custom babel options.

const run = require('babel-helper-transform-fixture-test-runner');
const path = require('path');
const testDir = path.join(__dirname, 'fixtures');
const opts = {
  presets: ['@babel/preset-env'],
  // Additional babel options
};
run(testDir, opts, function (err, results) {
  if (err) {
    console.error('Test failed:', err);
  } else {
    results.forEach(result => {
      console.log(result.title, result.pass ? 'PASS' : 'FAIL');
    });
  }
});