karma-rollup-preprocessor

Karma preprocessor to compile js files with rollup.

Support source maps (Karma reporter will log original file, line and column) and embed a file watcher to recompile and run the tests when a dependency is modified.

Installation

npm install rollup @metahub/karma-rollup-preprocessor --save-dev

Configuration

All the rollup options can be passed to rollupPreprocessor.options.

In addition the preprocessor accept a transformPath function, to rewrite the path on which the files are deployed on the Karma webserver. If not specified, the processed files will be accessible with the same paths as the originals. For example test/unit.test.js will be deployed as base/test/unit.test.js.

Standard

const babel = require('rollup-plugin-babel');

module.exports = function(config) {
  config.set({
    files: ['test/main.test.js', 'src/js/main.js'],

    plugins: ['@metahub/karma-rollup-preprocessor', 'karma-*'],
    preprocessors: {'**/*.js': ['rollup']},

    rollupPreprocessor: {
      options: {
        output: {
          // To include inlined sourcemaps as data URIs
          sourcemap: true,
          format: 'iife'
        },
        // To compile with babel using es2015 preset
        plugins: [babel({presets: [['es2015', {modules: false}]]})]
      },
      // File src/js/main.js will be deployed on Karma with path base/script/main.js
      transformPath: filePath => filePath.replace('src/js', 'script')
    },
  });
};

Note: Karma can auto-load plugins named karma-* (see plugins). Unfortunately it doesn't work with scoped packages, therefore @metahub/karma-rollup-preprocessor has to be explicitly added to the plugins configuration. In order to continue to automatically load other plugins you can add karma-* to the plugins configuration.

Note: @metahub/karma-rollup-preprocessor embed its own watcher to monitor js module dependencies, therefore only the main entry point has to be configured in Karma. If Karma is configured with autoWatch: true, the modification of an imported js module will trigger a new build and test run.

Configured Preprocessors

See configured preprocessors.

module.exports = function(config) {
  config.set({
    files: ['test/main.test.js', 'src/js/main.js'],

    plugins: ['@metahub/karma-rollup-preprocessor', 'karma-*'],
    preprocessors: {'src/**/*.js': ['rollup_1'], 'test/**/*.js': ['rollup_2']},

    customPreprocessors: {
      rollup_1: {
        base: 'rollup',
        options: {
          output: {
            sourcemap: false,
            format: 'iife'
          },
          plugins: [babel({presets: [['es2015', {modules: false}]]})]
        },
      },
      rollup_2: {
        base: 'rollup',
        options: {
          output: {
            sourcemap: true,
            format: 'iife'
          }
          plugins: [babel({presets: [['es2015', {modules: false}]]})]
        },
      },
    },
  });
};

Bundling tests

All tests files and their dependencies (and potentially sources) can easily be bundled in one package.

npm install rollup @metahub/karma-rollup-preprocessor rollup-plugin-babel babel-preset-es2015 rollup-plugin-glob-import  --save-dev

.
├── test
|   ├── main.js
|   ├── unit-test-1.test.js // imported by test/main.js
|   ├── unit-test-2.test.js // imported by test/main.js
|   ├── unit-test-3.test.js // imported by test/main.js
|   ├── helpers
|       └── utils.js // imported by unit-test-1.test.js, unit-test-2.test.js and unit-test-3.test.js
├── src
|   ├── main.js
|   ├── dependency.js // imported by src/main.js

// test/main.js

import './*.test.js'; // using https://github.com/kei-ito/rollup-plugin-glob-import

// test/unit-test-1.test.js

import {myUtil} from './helpers/utils.js';

describe('My unit tests', () => {
  it('shoud works', () => {
    ...
  });
});

// test/unit-test-2.test.js

import {myOtherUtil} from './helpers/utils.js';

describe('My other unit tests', () => {
  it('shoud also works', () => {
    ...
  });
});

const babel = require('rollup-plugin-babel');
const globImport = require('rollup-plugin-glob-import');

module.exports = function(config) {
  config.set({
    files: ['test/main.js', 'src/main.js'],

    plugins: ['@metahub/karma-rollup-preprocessor', 'karma-*'],
    preprocessors: {'**/*.js': ['rollup']},

    rollupPreprocessor: {
      options: {
        output: {
          sourcemap: true,
          format: 'iife'
        },
        plugins: [globImport(), babel({presets: [['es2015', {modules: false}]]})]
      },
    },
  });
};