karma-remap-coverage

Karma reporter that shows coverage for original non transpiled code (TypeScript, ES6/7, etc).

Build on top of karma-coverage and remap-istanbul - consumes coverage report for raw code and maps it to original files. Transpiler should generate source maps in order to make everything work.

Needs no temporary files nor npm post run scripts, works in "watch" mode generating report on every change.

Installation

npm install karma-remap-coverage --save-dev

Configuration

1. Enable source maps in your compiler config
2. Configure karma config to use karma-coverage together with karma-remap-coverage:
   • add remap-coverage to reporters list: reporters: ['progress', 'coverage', 'remap-coverage']
   • save interim coverage report in memory: coverageReporter: { type: 'in-memory' }
   • define where to save final reports: remapCoverageReporter: { html: './coverage' }
3. Optionally - configure remap options in karma config: remapOptions: { basePath: './dist' }

remapCoverageReporter format

Key-value pairs where key is report type and value - path to file/dir where to save it. Reporters like text-summary, text-lcov and teamcity can print out to console as well - in this case just provide any falsy value instead of path.
Example:

 remapCoverageReporter: {
  'text-summary': null, // to show summary in console
  html: './coverage/html',
  cobertura: './coverage/cobertura.xml'
}

TypeScript + webpack example

Karma config with alternative usage of karma-webpack should look something like this:

tsconfig.json

{
  "compilerOptions": {
    "sourceMap": true
    ...
  }
}

karma.conf.js

 module.exports = config => config.set({
  
  files: [
    './entry-module.spec.ts'
  ],
  preprocessors: {
    './entry-module.spec.ts': ['webpack', 'sourcemap'],
    './entry-module.ts': ['coverage']
  },
  
  ...
  
  // add both "karma-coverage" and "karma-remap-coverage" reporters
  reporters: ['progress', 'coverage', 'remap-coverage'],
  
  // save interim raw coverage report in memory
  coverageReporter: {
    type: 'in-memory'
  },
  
  // define where to save final remaped coverage reports
  remapCoverageReporter: {
    'text-summary': null,
    html: './coverage/html',
    cobertura: './coverage/cobertura.xml'
  },
  
  // make sure both reporter plugins are loaded
  plugins: ['karma-coverage', 'karma-remap-coverage']
  
});