tree: e00bc045564ff0786330aa8e0b07030ea5a066b4 [path history] [tgz]
  1. src/
  3. package.json


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A karma preprocessor that uses the latest istanbul 1.x APIs to instrument bundled ES5 or native ES6 code for coverage


This plugin instruments javascript code for coverage using the latest istanbul 1.x APIs. Source maps and mapping transpiled/bundled code to get coverage for the original source code is fully supported.

For configuring coverage output format, thresholds and other reporting options, please see karma-coverage-istanbul-reporter.


  • Unit testing native ES6 code with coverage in Karma and Chrome Headless, no bundling or transpiling: test/es6-native.

  • Unit testing Typescript code transpiled to ES6 + external source maps with coverage in Karma and Chrome Headless: test/external-sourcemap.

  • Unit testing Typescript code transpiled to ES6 + inline source maps with coverage in Karma and Chrome Headless: test/inline-sourcemap.

  • Unit testing ES6 code transpiled to ES5 with coverage in Karma and Chrome Headless, bundled with Rollup, transpiled with Babel: test/rollup.


npm install --save-dev karma-coverage-istanbul-instrumenter


module.exports = function(config) {

        // ...

        preprocessors: {
            "/!(*.spec).js": ["karma-coverage-istanbul-instrumenter"]

        coverageIstanbulInstrumenter: {
            esModules: true,
            // ... 

        // ...


The plugin supports all options supported by istanbul-lib-instrument:

    // Name of global coverage variable.
    coverageVariable: '__coverage__',

    // Preserve comments in output.
    preserveComments: false,

    // Generate compact code.
    compact: true,

    // Set to true to instrument ES6 modules.
    esModules: false,

    // Set to true to allow `return` statements outside of functions.
    autoWrap: false,

    // Set to true to produce a source map for the instrumented code.
    produceSourceMap: false,

    // Set to array of class method names to ignore for coverage.
    ignoreClassMethods: [],

    // A callback function that is called when a source map URL is found in the original code.
    // This function is called with the source file name and the source map URL.
    sourceMapUrlCallback: null,

    // Turn debugging on.
    debug: false,

    // Set plugins.
    plugins: [



© 2019 Erik Barke, Monounity