Some testing tools, such as Enzyme (we will learn about this in the following section), expect to be used in a web browser. In our example, the application uses nyc and ts-node to execute all our unit tests, which means that we are not using a web browser. Sometimes, it is possible to overcome this problem by using jsdom, which is described by its creators as follows:
"jsdom is a pure-JavaScript implementation of many web standards, notably the WHATWG DOM and HTML Standards, for use with Node.js. In general, the goal of the project is to emulate enough of a subset of a web browser to be useful for testing and scraping real-world web applications."
If we examine the nyc command in the package.json file included in the companion source ...
