Unable to run Coverage with Karma

Question

I'm trying to run coverage with karma, and I get the warning: WARN [preprocess]: Can not load "coverage", it is not registered!

I thought I installed coverage when I ran 'npm install -g karma-coverage --save-dev'

Here's my config file:

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

        frameworks: ['jasmine'],

        // list of files / patterns to load in the browser
        files: [
                bunch of files..
        ],

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

        // use dots reporter, as travis terminal does not support escaping sequences
        // possible values: 'dots', 'progress'
        // CLI --reporters progress
        reporters: ['progress', 'coverage'],

        junitReporter: {
          // will be resolved to basePath (in the same way as files/exclude patterns)
          outputFile: 'test-results.xml'
        },

        // web server port
        // CLI --port 9876
        port: 9876,

        // enable / disable colors in the output (reporters and logs)
        // CLI --colors --no-colors
        colors: true,

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

        // enable / disable watching file and executing tests whenever any file changes
        // CLI --auto-watch --no-auto-watch
        autoWatch: true,

        // Start these browsers, currently available:
        // - Chrome
        // - ChromeCanary
        // - Firefox
        // - Opera
        // - Safari (only Mac)
        // - PhantomJS
        // - IE (only Windows)
        // CLI --browsers Chrome,Firefox,Safari
        browsers: ['ChromeCanary'],

        // If browser does not capture in given timeout [ms], kill it
        // CLI --capture-timeout 5000
        captureTimeout: 20000,

        // Auto run tests on start (when browsers are captured) and exit
        // CLI --single-run --no-single-run
        singleRun: true,

        // report which specs are slower than 500ms
        // CLI --report-slower-than 500
        reportSlowerThan: 500,

        // compile coffee scripts
        preprocessors: {
            'someFileName': ['coverage'],
        },

        plugins: [
          'karma-jasmine',
          'karma-chrome-launcher',
          'karma-firefox-launcher',
        ],

    coverageReporter: {
        'type' : 'cobertura',
        'dir': 'coverage/'
    }

  });
};

Answer 1

I got the same [WARN] because the plugin 'karma-coverage' was not defined inside the plugins of the config, try to see if adding it fixes your warning, not sure if it will fix your full problem.

plugins: [
  'karma-jasmine',
  'karma-coverage',
  'karma-chrome-launcher',
  'karma-firefox-launcher',
],

UPDATE:
I also had a different problem when running the coverage, caused by istanbul, my error was

[coverage]: [TypeError: Cannot set property 'covered' of undefined]

After having a look what istanbul was doing it turned out that the paths to some of my js unit files were outdated in the preprocessors.

It was doing some of the coverage reports but it was not generating deep coverage reports for all files hence the error. Once I fixed the paths it was all good.

    preprocessors : {
        '**/app/js/*/*.js' : 'coverage',
        '**/app/js/modules/*/*.js' : 'coverage',
        '**/app/js/services/*/*.js' : 'coverage'
    },