karma.conf.js

// Karma configuration

const aliases = require('./aliases');

module.exports = function (config) {
  config.set({
    // base path that will be used to resolve all patterns (eg. files, exclude)
    basePath: '',

    plugins: [
      'karma-mocha',
      'karma-chai',
      'karma-webpack',
      'karma-mocha-reporter',
      'karma-chrome-launcher',
    ],

    // frameworks to use
    // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
    frameworks: ['mocha', 'chai'],

    // list of files / patterns to load in the browser
    files: ['test/**/*.test.ts'],

    // list of files to exclude
    exclude: [],

    webpack: {
      mode: 'development',
      module: {
        rules: [
          {
            test: /\.ts$/,
            loader: 'babel-loader',
            options: {
              presets: ['@babel/preset-typescript'],
              plugins: [
                '@babel/plugin-syntax-dynamic-import',
                '@babel/plugin-proposal-object-rest-spread',
                '@babel/plugin-proposal-class-properties',
              ],
            },
          },
        ],
      },
      resolve: {
        alias: { ...aliases },
        extensions: ['.js', '.jsx', '.tsx', '.ts', '.json'],
      },
    },

    // preprocess matching files before serving them to the browser
    // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
    preprocessors: {
      'test/**/*.test.ts': ['webpack'],
    },

    // test results reporter to use
    // possible values: 'dots', 'progress'
    // available reporters: https://npmjs.org/browse/keyword/karma-reporter
    reporters: ['mocha'],

    // web server port
    port: 9876,

    // enable / disable colors in the output (reporters and logs)
    colors: true,

    // level of logging
    // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
    logLevel: config.LOG_INFO,

    // enable / disable watching file and executing tests whenever any file changes
    autoWatch: true,

    // start these browsers
    // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
    browsers: ['Chrome'],

    // Continuous Integration mode
    // if true, Karma captures browsers, runs the tests and exits
    singleRun: false,

    // Concurrency level
    // how many browser should be started simultaneous
    concurrency: Infinity,
  });
};