Setting up cloud coverage statistics

It is very useful to track coverage status changes after commits:

• It reveals risky changes early
• It gives a clear warning to go ahead and fix it before it gets out of hand

For this example, we will use a free service called Coveralls:

$ npm install react react-dom --save
$ npm install coveralls jest next react-test-renderer --save-dev

Same as before; we need to configure Babel too:

// .babelrc
{
  "env": {
    "test": {
      "presets": [
        [
          "env",
          {
            "modules": "commonjs"
          }
        ],
        "next/babel"
      ]
    },
    "development": {
      "presets": [
        "next/babel"
      ]
    }
  }
}

Let's configure Jest to collect coverage for us:

// jest.config.js
module.exports = {
    testPathIgnorePatterns...