React Tests
Unit Testing
recap
Goals / why write tests
- find bugs?
- prevent bugs
- help to understand code
- keep jr. devs busy :)
What is unit?
- function? class? module?
- entire app?
- entire app + environment?
Terms
- mocks / stubs
- code coverage
- unclear scope
- no assertions
- fail randomly
- hardly readable
- adapt to the code
- excessive mocks
- it's clear what unit is
- one assertion*
- fail only when something is broken
- look like documentation
- shape the code
- no mocks
React Testing
1. Read the docs
2. Test a real project
let unit = 'function';
- extract complex pieces of logic
- test them
let unit = 'component';
- Create a <Component with='props' />
- Run asserts on it...
- via DOM API with jsdom
- make html snapshot
- compare screenshots
let unit = 'story';
backstopjs + storybook = a match made in heaven
let unit = 'application';
Out of today's scope.
When needed - take a look at cypress.io
https://youtu.be/gK5I7bq72Fw?t=3814 - react2020q1