At the end of the day, all you need to do is place the bin nyc in front of the existing test scripts in your package.json:

{
  "scripts": {
    "test": "nyc ava --timeout=3000"
  }
}

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

#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, or would like to run multiple reporters, simply use the --reporter flag.

for instance, suppose you would like to output the default text report, along with an HTML coverage report.

{
  "scripts": {
    "test": "nyc --reporter=html --reporter=text ava"
  }
}

This will output the text report to the terminal, as well as outputting the detailed html report to ./coverage/index.html.

#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:

1. add the coveralls dependency to your module:

npm install coveralls --save-dev

2. update the scripts in your package.json to include a bin for reporting coverage to coveralls:

{
  "script": {
     "test": "nyc --reporter=html --reporter=text ava",
     "coverage": "nyc report --reporter=text-lcov | coveralls"
  }
}

3. For private repos, add the environment variable COVERALLS_REPO_TOKEN to Travis.

4. add the following to your .travis.yml:

after_success: npm run coverage

#What about TypeScript?

AVA has a TypeScript recipe that should get you started. Feel free to contribute to their docs or make a PR here if you have more details to share! :smile:

#What Now?

nyc and Istanbul provide many advanced configuration options a good place to start learning more is the istanbuljs/nyc README.