karma-rollup-plugin 

> A Karma preprocessor plugin to offer seamless integration with rollup

This plugin is a Karma preprocessor to compile and bundle your spec entry point on the fly. It works seamless with all Rollup plugins.

Features

- supports Rollup by default
- supports both Babel and Buble as the ES2015 compiler
- sourceMap
- recompiling of dependencies when files changes
- ES3, ES5, ES2015, ES2016, and ES2017 (with Babel or Buble)

Installation

The easiest way is to keep karma-rollup-plugin as a devDependency. You can simple do it by:

``js
npm i karma-rollup-plugin --save-dev
`

Configuration

Note! As a rule of thumb, use of umd format doesn't make sense in tests, and will throw a warning without a module name.

Following code shows the default configuration

`js
// karma.conf.js
module.exports = function (config) {
config.set({
preprocessors: {
'test/*/.js': ['rollup']
},
rollupPreprocessor: {
// rollup settings. See Rollup documentation
plugins: [
buble() // ES2015 compiler by the same author as Rollup
],
// will help to prevent conflicts between different tests entries
format: 'iife',
sourceMap: 'inline'
}
});
};
`

See Rollup documentation - JavaScript API for more details.

Why this plugin?

There exist a karma-rollup-preprocessor plugin for Karma, but it contains too many bugs, and doesn't seem to be maintained atm.
This plugin try to stay true to the Rollup ecosystem`.