@jsdevtools/coverage-istanbul-loader

What is @jsdevtools/coverage-istanbul-loader?

@jsdevtools/coverage-istanbul-loader is a Webpack loader that instruments your code with Istanbul coverage when running tests. It is typically used in conjunction with test runners like Mocha, Karma, or Jest to generate code coverage reports.

What are @jsdevtools/coverage-istanbul-loader's main functionalities?

Instrumenting Code for Coverage

This feature allows you to instrument your JavaScript code for coverage. The loader processes files matching the specified test pattern (in this case, .js files in the src directory) and instruments them using Istanbul.

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        include: /src/,
        loader: '@jsdevtools/coverage-istanbul-loader'
      }
    ]
  }
};

Combining with Other Loaders

This feature demonstrates how to combine @jsdevtools/coverage-istanbul-loader with other loaders, such as babel-loader. This is useful for transpiling ES6+ code and then instrumenting it for coverage.

module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        include: /src/,
        use: [
          'babel-loader',
          '@jsdevtools/coverage-istanbul-loader'
        ]
      }
    ]
  }
};

Other packages similar to @jsdevtools/coverage-istanbul-loader

istanbul-instrumenter-loader

istanbul-instrumenter-loader is another Webpack loader for instrumenting JavaScript files with Istanbul coverage. It is similar to @jsdevtools/coverage-istanbul-loader but is an older package and may not have the latest updates and features.

babel-plugin-istanbul

babel-plugin-istanbul is a Babel plugin that instruments your code with Istanbul coverage. Unlike @jsdevtools/coverage-istanbul-loader, which is a Webpack loader, this package integrates directly with Babel, making it a good choice if you are already using Babel for transpilation.

karma-coverage-istanbul-reporter

karma-coverage-istanbul-reporter is a Karma reporter that uses Istanbul to generate code coverage reports. It is specifically designed to work with the Karma test runner, whereas @jsdevtools/coverage-istanbul-loader is more general-purpose and can be used with various test runners.

README

Istanbul code coverage loader for Webpack

This is a Webpack loader that uses Istanbul to add code coverage instrumentation to your code. This is especially useful for in-browser testing, in a tool like Karma, where you can use karma-coverage-istanbul-reporter to output code coverage data in a variety of formats that are supported by services like Coveralls or Codacy.

Coverage Istanbul Loader is based on Istanbul Instrumenter Loader, but uses a newer version of the Istanbul API and has better support for source maps.

Usage

See the examples folder for usage examples for various use cases.

• "hello, world" example
  This is the most simplistic example. It just uses coverage-istanbul-loader with its default options to produce an output bundle that contains code coverage instrumentation.

• TypeScript example
  This example demonstrates using coverage-istanbul-loader with transpiled code. It correctly maps the instrumented JavaScript code back to the original TypeScript source code.

• Karma example
  This example demonstrates using coverage-istanbul-loader with Karma and karma-coverage-istanbul-reporter to produce code coverage reports for browser tests.

• Example with options
  This example demonstrates passing options to coverage-istanbul-loader. The options are passed-on to istanbul-lib-instrument, so all the same options are supported.

Contributing

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

Building/Testing

To build/test the project locally on your computer:

1. Clone this repo
   git clone https://github.com/JS-DevTools/coverage-istanbul-loader.git

2. Install dependencies
   npm install

3. Build the code
   npm run build

4. Run the tests
   npm test

License

coverage-istanbul-loader is 100% free and open-source, under the MIT license. Use it however you want.

Big Thanks To

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