karma-es6-module-preprocessor

0.2.0 verified Fri May 01 auth: no javascript deprecated

A Karma preprocessor that compiles ES6 module syntax (import/export) to ES5 using the es6-module-transpiler. Version 0.2.0 is the latest and appears to be unmaintained since 2014. It integrates with Karma test runner to transpile ES6 modules on the fly during testing. Note that the es6-module-transpiler project itself is deprecated in favor of Babel or TypeScript. This preprocessor is specific to the es6-module-transpiler and does not support newer transpilers like Babel. For modern projects, use karma-babel-preprocessor instead.

Common errors

error Module "es6-module-transpiler" not found ↓

cause The es6-module-transpiler is not installed as a dependency and this preprocessor depends on it.

fix

Install es6-module-transpiler as a devDependency: npm install es6-module-transpiler --save-dev

error No provider for "framework:karma-es6-module-preprocessor"! ↓

cause The plugin is listed in karma.conf.js with an incorrect name or not installed.

fix

Add 'karma-es6-module-preprocessor' to plugins array and ensure it is installed.

error TypeError: Cannot read property 'transpile' of undefined ↓

cause The es6-module-transpiler has not been found or initialization failed.

fix

Ensure es6-module-transpiler is installed and the path is correct.

Warnings

deprecated The es6-module-transpiler project is deprecated and no longer maintained. This preprocessor relies on an outdated transpiler. ↓

fix Migrate to karma-babel-preprocessor with appropriate Babel presets for ES6 modules.

gotcha Preprocessor name must be 'es6' in preprocessors config, not 'es6-module' or 'karma-es6-module-preprocessor'. ↓

fix Use 'es6' as the preprocessor name in the preprocessors object.

gotcha Karma plugins must include the full plugin name prefixed with 'karma-' if using short names. ↓

fix Set plugins: ['karma-es6-module-preprocessor'] in karma.conf.js.

breaking This plugin only supports Karma >=0.12.0. Older versions are incompatible. ↓

fix Upgrade Karma to version 0.12.0 or later.

Install

npm install karma-es6-module-preprocessor

yarn add karma-es6-module-preprocessor

pnpm add karma-es6-module-preprocessor

Imports

default (plugin)
wrong
```
plugins: ['es6-module-preprocessor']
```
correct
```
plugins: ['karma-es6-module-preprocessor'] in karma.conf.js
```
Karma plugin names must be prefixed with 'karma-' when given as short names in plugins array.
preprocessor configuration
wrong
```
preprocessors: { '**/*.js': ['es6-module'] }
```
correct
```
preprocessors: { '**/*.js': ['es6'] }
```
The preprocessor name in the preprocessors object is 'es6', not 'es6-module'.

CommonJS require

wrong

var es6ModulePreprocessor = require('karma-es6-module-preprocessor').default;

correct

var es6ModulePreprocessor = require('karma-es6-module-preprocessor');

The package exports a function as module.exports, not a default export.

Quickstart

Karma configuration to transpile ES6 modules to ES5 using the karma-es6-module-preprocessor during testing.

// karma.conf.js
module.exports = function(config) {
  config.set({
    frameworks: ['jasmine'],
    plugins: ['karma-es6-module-preprocessor', 'karma-jasmine', 'karma-chrome-launcher'],
    preprocessors: {
      '**/*.js': ['es6']
    },
    files: [
      'src/**/*.js',
      'test/**/*.test.js'
    ],
    browsers: ['ChromeHeadless'],
    singleRun: true
  });
};