karma-rollup-preprocessor

Karma + Rollup

Karma preprocessor to bundle ES2015 modules using Rollup.

Features

• Rebundles your files when watched dependencies change
• Caches bundle output for improved performance
• Maintained with by @jlmakes

Installation

npm install karma-rollup-preprocessor

Configuration

All the options detailed in the Rollup Documentation can be passed to rollupPreprocessor.

Standard

Below is a well-founded recommendation using the Bublé ES2015 transpiler:

// karma.conf.js
module.exports = function(config) {
	config.set({
		files: [
			// Make sure to disable Karma’s file watcher
			// because the preprocessor will use its own.
			{ pattern: 'test/**/*.spec.js', watched: false }
		],

		preprocessors: {
			'test/**/*.spec.js': ['rollup']
		},

		rollupPreprocessor: {
			plugins: [require('rollup-plugin-buble')()],
			format: 'iife', // Helps prevent naming collisions.
			name: '<your_project>', // Required for 'iife' format.
			sourcemap: 'inline' // Sensible for testing.
		}
	})
}

Configured Preprocessors

Below shows an example where configured preprocessors can be very helpful:

// karma.conf.js
module.exports = function(config) {
	config.set({
		files: [{ pattern: 'test/**/*.spec.js', watched: false }],

		preprocessors: {
			'test/buble/**/*.spec.js': ['rollup'],
			'test/babel/**/*.spec.js': ['rollupBabel']
		},

		rollupPreprocessor: {
			plugins: [require('rollup-plugin-buble')()],
			format: 'iife',
			name: '<your_project>',
			sourcemap: 'inline'
		},

		customPreprocessors: {
			// Clones the base preprocessor, but overwrites
			// its options with those defined below...
			rollupBabel: {
				base: 'rollup',
				options: {
					// In this case, to use a different transpiler:
					plugins: [require('rollup-plugin-babel')()]
				}
			}
		}
	})
}

Support

Supports all Rollup plug-ins, and works on Node 4 and up. Happy bundling!

Changelog

[5.0.3] - 2018-01-05

Changed

• Upgraded Chokidar dependency.