Hark! What is this Jest you speak of?
Think of it as several layers of improvement stuck on top of Jasmine. Some of the neat features Jest provides are:
- Automatically finds tests to run in your project
- Has in built support for fake DOM APIs, such as jsdom, that you can run from the command line
- You can test asynchronous code more easily using inbuilt mocked timer functions
- Tests are run in parallel so they go faster! Vroom vroom.
But the big drawcard is Jest’s automatic mocking of CommonJS dependencies using the require() function. Instead of specifying all the dependencies you want mocked, you do the opposite. For the subject under test, you just use jest.dontMock().