Using Istanbul With Node Tap

Node Tap uses nyc to track code coverage, even across subprocess boundaries. It is included by default, and there’s nothing you need to do but enable it.

More detail about node-tap's coverage information can be found in the node-tap.org documentation.

{
  "scripts": {
    "test": "tap test/*.js --coverage"
  }
}

that's it! this will instrument the code that your tests execute, and any subprocesses that it spawns.

#Maximal Coverage 💯

As of version 7, node-tap lets you easily enforce 100% coverage of all lines, branches, functions, and statements with one easy flag, if that's your thing:

{
  "scripts": {
    "test": "tap test/*.js --100"
  }
}

#Using Alternative Reporters

By default nyc uses Istanbul's text reporter. Various other reporters are available. You can view the full list on the Using Alternative Reporters page.

If you'd like to specify alternate reporter, use the --coverage-report flag.

{
  "scripts": {
    "test": "tap --coverage --coverage-report=html"
  }
}

This will output detailed html report to ./coverage/index.html. By default, it will also open up the file in your web browser.

#Integrating with Coveralls

coveralls.io is a great tool for adding coverage reporting to your continuous-integration flow. Here's how to get Istanbul integrated with coveralls and travis-ci.org. Here are the steps to link up your travis jobs with Coveralls if you're using node-tap:

1. Add the environment variable COVERALLS_REPO_TOKEN to your Travis environment.

That's it!