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Question

I am trying to use karma to test my file array.js, this file is only 36 lines, BUT, the coverage report shows "Lines ...."(see the png I upload), what's the meaning of the values, why it not match my test code? Is the reason I use es6? How can I get the correct report?

The karma-config,

const webpackConfig = {
  devtool: 'inline-source-map',
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /(node_modules|vendor)/,
        loader: 'babel-loader'
      }
    ]
  }
};

module.exports = function (config) {
  config.set({
    basePath: '../',
    plugins: [
      'karma-webpack',
      'karma-mocha',
      'karma-phantomjs-launcher',
      'karma-verbose-reporter',
      'karma-coverage'
    ],
    webpack: webpackConfig,
    webpackServer: {
      noInfo: true
    },
    frameworks: ['mocha'],
    files: [
      'test/**/*.js',
      'src/**/*.js'
    ],
    preprocessors: {
      'test/**/*.js': ['webpack'],
      'src/**/*.js': ['webpack', 'coverage']
    },
    reporters: ['verbose', 'coverage'],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['PhantomJS'],
    concurrency: Infinity,
    coverageReporter: {
      includeAllSources: true,
      dir: 'coverage/',
      reporters: [
        {type: "html", subdir: "html"},
        {type: 'text-summary'}
      ]
    }
  });
};

Answer 1

Karma executes all the files under your testing scope from your projects. The report you are getting is for all the files in your project. Following is the explanation of each values:

Statements : Has each statement in the program been executed?

Branches : Has each branch (also called DD-path) of each control structure (such as in if and case statements) been executed? For example, given an if statement, have both the true and false branches been executed? Another way of saying this is, has every edge in the program been executed?

Functions : Has each function (or subroutine) in the program been called?

Lines : has each executable line in the source file been executed?

Detailed description: https://en.wikipedia.org/wiki/Code_coverage