Encountered an unexpected token error when executing karma-coverage in a project using TypeScript

I have been working on a simple Angular/Typescript project that includes 12 basic unit tests which all pass successfully. However, I am now looking to measure the code coverage of these tests. Despite trying different methods, I have not been able to achieve this and have decided to start fresh with karma-coverage and seek assistance here.

When running karma, I encounter an error message for each source file similar to:

Failed to parse file: C:/Users/FRBA/Documents/MyProject/src/app/nav/new-panel/new-panel.component.ts
07 07 2017 07:54:35.832:ERROR [preprocessor.coverage]: Line 1: Unexpected token
  at C:/Users/FRBA/Documents/MyProject/src/app/nav/new-panel/new-panel.component.ts

The configuration in my karma.conf.js file is as follows:

var path = require('path');
module.exports = function (config) {
  config.set({
    files: [
      'src/app/**/*.ts',
      'test/app/**/*.ts'
    ],
    basePath: '',
    frameworks: ['jasmine', '@angular/cli'],
    plugins: [
      require('karma-jasmine'),
      require('karma-chrome-launcher'),
      require('karma-ie-launcher'),
      require('karma-jasmine-html-reporter'),
      require('karma-coverage'),
      require('@angular/cli/plugins/karma')
    ],
    client: {
      clearContext: false
    },
    angularCli: {
      environment: 'dev'
    },
    reporters: ['progress', 'kjhtml', 'coverage'],
    preprocessors: {
      'src/app/**/*.ts': ['coverage']
    },
    coverageReporter: {
      type : 'html',
      dir : 'coverage/'
    },
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: true,
    browsers: ['Chrome', 'IE'],
    singleRun: false
  });
};

I have attempted several solutions - including karma-coverage, karma-coverage-istanbul-reporter, and karma-typescript - but encountered issues like empty reports and stalled execution. It seems there may be a fundamental error in my approach. Any guidance or tutorials tailored to beginners in karma (and Typescript) would be greatly appreciated. Thank you!

Answer №1

According to the karma-typescript documentation found at this link, it is necessary to include karma-typescript as a preprocessor. If you are working with TypeScript files (which can be inferred from the .ts extension), they must be transpiled into JavaScript for other processors to interpret them correctly. The error message about an unexpected token most likely pertains to a token that is only valid in TypeScript.

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