karma-rollup-preprocessor

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: {
      /**
       * This is just a normal Rollup config object,
       * except that `input` is handled for you.
       */
      plugins: [require("rollup-plugin-buble")()],
      output: {
        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")()],
      output: {
        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 8 and up. Happy bundling!

Changelog

[7.0.0] - 2019-02-06

Added

• Support for Rollup 1.0.0 #42

Changed

• Breaking: Dropped support for Rollup < 1.0.0
• Breaking: Dropped support for Node < 8.0.0
• Watcher no longer relies on Karma’s run_start event. #41
• Upgraded dependencies.

Fixed

• Watcher only rebundles changed files and their dependents. #28
• Bundle cache now properly maps each entry to its bundle cache.