About this repository

Setting up Jest

Jest is currently set up for you in this project. If you're interested in how it was set up:

1. `npm install --save-dev jest @babel/core @babel/jest @babel/preset-env`

Several packages are installed via NPM.

jest - this is the Jest library itself.
@babel/core - this is the core of BabelJs. It allows us to use modern JavaScript features, and not worry about old browsers not understanding them.
@babel/jest - this is an adapter to connect Babel with Jest, so our tests can run our modern JavaScript code.
@babel/preset-env - this is a preset for Babel. It allows us to tell Babel to figure out how it needs to transpile code for the current environment.

2. `.babelrc` file added

We add a .babelrc file, which configures the @babel/preset-env preset.

3. Test scripts added to `package.json`.

We add a handful of scripts to npm, all for running our tests via Jest.

test - runs all tests in the project, one time.
test-watch-all - runs all tests in the project, in watch mode.
test-watch-module-1 - runs only module-1 tests, in watch mode.
test-watch-module-2 - runs only module-2 tests, in watch mode.
...