Enzyme

We use Jest because when we rebooted our "front end" stack earlier last year, we need to have a testing solution (we didn't have any front-end tests before that!). Jest is fast and convenient and it has plenty of community support behind it. It let's us run our unit tests with Enzyme and snapshot tests.

This is an area that we are constantly reviewing to see what can be improved, both in terms of developer needs, accuracy, test maintainability, and coverage.

I'm currently exploring using React Storybook to be the record of snapshot tests and using some online services, such as Happo.io and Percy in our CI pipeline.

I use both mocha and Jest because:

• I don't care whether teams use Jest or Mocha. But jest is way too overhyped. Most devs are writing integration tests and think that it's so much better but frankly I don't write integration tests as the way to get both design feedback and confidence when I code. I adhere to the test pyramid, not ice cream cone or the dumb "trophy"

• I TDD, so I only ever use the "API" of test frameworks. I don't do a lot of integration tests for TDD and all the bells and whistles Jest provides you from the command-line I just don't need. And I certainly do not care about or touch Jest Snapshots, I despise them

• My tests are fast enough because I write isolated tests with TDD, so I don't run into performance issues. Example: I write my tests in a way that I can run 300 tests in literally 1 second with mocha. So the Jest ability to pinpoint and only run those tests which are affected by code changes. I want to run all of them every time when I TDD. It's a different mindset when you TDD

• I also mainly code in IntelliJ or WebStorm because I feel the tools in that IDE far surpass VSCode and I also love running the test UI runner in it vs. lousy command-line

• I feel both mocha and Jest read just fine in terms of code readability. Jest might have shorter assertion syntax but I don't really care. I just care that I can read the damn test and my tests are written well and my test descriptions, as well as the code itself including constants represent business language, not technical. I care most about BDD, clean code, 4 rules of simple design, and SOLID

• I don't like using mock frameworks so no I don't use Jest's Mocking framework. I don't have to mock a lot in my tests due to the nature of how I strive to code...I keep my design simple and modular using principals such as clean code and 4 rules of simple design. If I must mock, I create very simple custom mocks with JS

• On the contrary to the belief that integration tests and mount are the way to go (this belief drives me absolutely crazy, especially Dodd's promoting that), I TDD with shallow & enzyme. My tests are simple. My design is driven by my tests and my tests give me quick and useful feedback. I have a course I'm working on coming out soon on TDD with React to show you how to truly test the FE and why the ice cream cone and trophy suck (you're being scammed people). Watch for that here: https://twitter.com/DaveSchinkel/status/1062267649235791873

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Mocha Jest JavaScript React @jsdom Enzyme ##tdd ##bdd ##testdrivendevelopment