Karma Config

Karma configuration builder with sensible defaults to minimize boilerplate

Karma can be configured to do pretty much anything you can imagine, but you'll probably find yourself repeating the same boilerplate configuration in every project.

Karma Config eliminates the redundancy and boilerplate by applying sensible defaults so you only need to specify the one-off settings that are particular to your project. It can reduce a typical karma.config.js file from dozens of lines to just two or three lines.

Features

Applies sensible defaults, but will never override your settings
Uses the appropraite browsers for the platform (e.g. Safari on Mac, Edge on Windows)
Uses headless browsers when running in CI/CD
Produces code-coverage reports if KARMA_COVERAGE env var is set, or if you add --coverage when running Karma

Related Projects

karma-host-environment
Provides host environment info (user agent, Node.js version, environment variables, etc.)

Installation

Use npm to install Karma Config as a dev dependency. Be sure to install karma and karma-cli too.

npm install --save-dev karma karma-cli @jsdevtools/karma-config

Usage

Using Default values

For typical projects, the defaults may be all you need, in which case your config can be one line:

karma.conf.js

module.exports = require("@jsdevtools/karma-config")();

Depending on the operating system and whether its running in a CI/CD environment, the above code will produce this config:

{
  // Defaults to the Karma-Verbose-Reporter
  // See https://www.npmjs.com/package/karma-verbose-reporter
  reporters: ["verbose"],

  // The browsers will vary depending on the OS.
  // In CI/CD environments, FirefoxHeadless and ChromeHeadless are used instead.
  browsers: ["Firefox", "Chrome"],

  frameworks: [
    // Defaults to the Mocha test framework.
    "mocha",

    // This makes it easy to detect which browser your tests are running in.
    // Also provides access to environment variables.
    // See https://jstools.dev/karma-host-environment
    "host-environment"
  ],

  files: [
    // Assumes your tests are under the "test" folder and are named *.spec.js
    // or *.test.js.  (.mjs and .jsx file extensions are also supported)
    "test/**/*.+(spec|test).+(js|jsx|mjs)",

    // Allows your tests to dynamically access any file in the "test" folder.
    // Useful for loading test data from CSV or JSON files.
    { pattern: "test/**/*", included: false, served: true }
  ],

  preprocessors: {
    // Uses Webpack to bundle your tests and their dependencies
    "test/**/*.+(spec|test).+(js|jsx|mjs)": ["webpack"]
  },

  webpack: {
    // Webpack development mode it easier to debug failing tests
    mode: "development",

    // Inlne source maps ensure proper stack traces in errors,
    // and allow you to debug your original source code rather than bundled code.
    devtool: "inline-source-map",
  }
}

Adding or Overriding Settings

You can explicitly specify any Karma settings, and Karma Config will honor them. Your settings will be merged with the settings that Karma Config generates. This allows you to add additional settings that aren't normally set by Karma Config. It also allows you to override anything that Karma Config would normally generate.

karma.conf.js

module.exports = require("@jsdevtools/karma-config")({
  config: {
    port: 12345,                                    // Set Karma's port number
    browserNoActivityTimeout: 5000,                 // Set Karma's inactivity timeout
    browsers: ["Opera", "Safari"]                   // Always use these browsers, regardless of OS
    webpack: {
      resolve: {
        extensions: [".js", ".jsx", ".ts", ".tsx"]  // Configure Webpack to resolve TypeScript file
      },
      mode: "production",                           // Override the default Webpack mode
      module: {
        rules: [
          { test: /\.ts$/, use: "ts-loader" }       // Configure Webpack to support TypeScript
        ]
      }
    }
  }
});

Another option is to use Karma Config's buildConfig function, which returns the generated config object. You can then make whatever modifications you want to it before passing it to Karma.

karma.conf.js

const { buildConfig } = require("@jsdevtools/karma-config");

module.exports = (karma) => {
  // Let Karma Config generate its config, as usual
  let config = buildConfig();

  // Modify the config object however you want
  config.port = 12345;
  config.browserNoActivityTimeout = 5000;
  config.browsers.push("Opera");
  config.webpack.mode = "production";
  config.webpack.module.rules.push({ test: /\.ts$/, use: "ts-loader" });

  // Pass the final config to Karma
  karma.set(config);
});

Options

Karma Config exposes a few options that allow you to control the config that it generates. Here's an example that demonstrates setting a few options:

karma.conf.js

module.exports = require("@jsdevtools/karma-config")({
  sourceDir: "my/source/dir",             // Override the default sourceDir ("src")
  testDir: "my/test/dir",                 // Override the default testDir ("test")
  coverage: true,                         // Always produce a code-coverage report
  browsers: {
    firefox: false,                       // Never test in Firefox
    ie: true,                             // Always test in Internet Explorer
  }
});

All Options

Option	Type	Default Value	Description
`browsers`	`object`		This object allows you to specify which browsers to test on
`browsers.chrome`	`boolean`	`true` for Linux `false` on other platforms	Whether to test on Chrome.
`browsers.firefox`	`boolean`	`true` for Linux `false` on other platforms	Whether to test on Firefox.
`browsers.safari`	`boolean`	`true` for Mac `false` on other platforms	Whether to test on Safari. Can use SauceLabs if configured.
`browsers.edge`	`boolean`	`true` for Windows `false` on other platforms	Whether to test on Edge (the EdgeHTML engine, not Chromium). Can use SauceLabs if configured.
`browsers.ie`	`boolean`	`false`	Whether to test on Internet Explorer. Can use SauceLabs if configured.
`sourceDir`	`string`	`src`	The relative path of the source directory.
`testDir`	`string`	`test`	The relative path of the test directory.
`tests`	`string` `string[]` `object` `object[]`	`${testDir}/*/.spec.js` `${testDir}/*/.test.js` `${testDir}/*/.spec.jsx` `${testDir}/*/.test.jsx` `${testDir}/*/.spec.mjs` `${testDir}/*/.test.mjs`	One or more file patterns that specify your test files. These are the files that will be bundled by Webpack and run by Karma.
`fixtures`	`string` `string[]` `object` `object[]`	none	One or more file patterns that specify your test fixtures. Test fixtures will be run before any of your test files are loaded, which gives you an opportunity to setup the runtime environment, load polyfills, etc.
`serve`	`string` `string[]` `object` `object[]`	`${testDir}/*/`	One or more file patterns that Karma will allow to be served. This is useful for loading test data from CSV or JSON files.
`transpile`	`boolean`	`false`*	Indicates whether your source code should be transpiled to ES5 syntax to support older web browsers. If set to `true`, then Webpack will be configured to use Babel. * If `browsers.ie` is enabled, then this option defaults to `true` when running on Windows. You can explicitly set it to `false` if desired.
`coverage`	`boolean`	`false`	Indicates whether code coverage analysis should be performed. If set to `true`, then Webpack will be configured to inject code-coverage instrumentation and write code-coverage reports in the `./coverage/` directory. This option can also be enabled by setting the `KARMA_COVERAGE` environment variable, or by using the `--coverage` command-line flag when running Karma.
`platform`	`string`	`process.platform`	The operating system platform (e.g. "linux", "win32", "darwin", etc.). This determines which browsers will be launched by Karma.
`CI`	`boolean`	auto-detected	Indicates whether Karma is running in a CI environment. If set to `true`, then Karma will be configured to run headless browsers where possible. Karma Config will auto-detect most CI environments. This option can also be enabled by setting the `CI` or `KARMA_CI` environment variables.
`config`	`object`	`{}`	Explicit Karma configuration settings. This is useful for adding additional settings that aren't normally set by Karma Config, or for overriding Karma Config's settings.

SauceLabs

Safari, Edge, and Internet Explorer aren't supported on some CI/CD services. Karma Config allows you to use SauceLabs to test on these browsers.

Karma Config uses the Sauce Connect proxy to open a secure channel to SauceLabs. Sauce Connect is only supported on Linux and requires the SAUCE_USERNAME and SAUCE_ACCESS_KEY environment variables to be set.

module.exports = require("@jsdevtools/karma-config")({
  browsers: {
    // No need to explicitly set these, since they are tested by default on Linux
    // firefox: true,
    // chrome: true,

    // Test these browsers using SauceLabs
    ie: true,
    edge: true,
    safari: true,
  }
});

Contributing

Contributions, enhancements, and bug-fixes are welcome! Open an issue on GitHub and submit a pull request.

Building/Testing

To build/test the project locally on your computer:

Clone this repo
git clone hhttps://github.com/JS-DevTools/karma-config.git
Install dependencies
npm install
Build the code
npm run build
Run the tests
npm test

License

Karma Config is 100% free and open-source, under the MIT license. Use it however you want.

This package is Treeware. If you use it in production, then we ask that you buy the world a tree to thank us for our work. By contributing to the Treeware forest you’ll be creating employment for local families and restoring wildlife habitats.

Big Thanks To

Thanks to these awesome companies for their support of Open Source developers ❤

License

JS-DevTools/karma-config

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