This guide details using Blanket.js with a locally installed mocha testrunner with their built-in html-cov reporter in NodeJS by using configuration options in package.json. This is useful for running coverage on remote continuous integration services like CircleCI or TravisCI.

It is assumed you have already read the Getting Started guide.

1. Install Mocha locally: npm install mocha --save-dev

2. Install Blanket: npm install blanket --save-dev

3. Install mocha-multi so we can use two reporters at once. One reporter is the result of the tests, and the other is for coverage. npm install mocha-multi --save-dev

4. In your package.json file, add the following:

  "scripts": {
    "start": "node app.js",
    "test": "multi='dot=- html-cov=coverage.html' ./node_modules/mocha/bin/mocha -r blanket --reporter mocha-multi --no-colors"
  },
  "config": {
    "blanket": {
      "pattern": "//\/[\\w-]+\\.js$/",
      "data-cover-never": [
        "node_modules",
        "public"
      ],
      "data-cover-reporter-options": {
        "shortnames": true
      }
    }
  },

In this example, we're not unit testing the node_modules or the public directories, and we're only reporting coverage for files that only have letters or dashes in their names. This would show coverage for index.js, but not index.test.js.

The short names option would only report the file's name, and not its complete path.

4. Run npm test. It will report the results of the unit tests, and create coverage.html in your project's root.