Getting started
Prerequisites
Optional dependencies
- GraphicsMagick for gm diffing engine,
brew install graphicsmagick - Docker for the
chrome.dockertarget. - Chrome 59+ for the
chrome.apptarget,brew cask install google-chrome-canary. - react-native-devsettings-android for self-healing crashes on android.
Installation
yarn add loki --dev
yarn loki init
Manually
Optionally add loki configuration and integrate as follows:
React native
Add import 'loki/configure-react-native' to storybook/storybook.js.
Others
When running a recent version of Storybook, no further integration should be needed. If you are running an old version, you might need to add import 'loki/configure-react' to .storybook/preview.js (create it if it doesn't exist already).
Running your first tests
1. Review configuration
The loki init command will detect what type of project it is and add default configurations to your package.json file under the key loki. For web this is testing laptop and iPhone configurations using local Chrome app. You can change this at any time.
2. Start Storybook
For loki to be able to access your stories you must start the storybook server. Usually this will be done with yarn storybook. You can run React and React Native storybook servers and tests simultaneously as long as they run on different ports. If you test against iOS simulator or Android emulator, these must also be running the storybook app, start them with react-native run-ios and react-native run-android respectively.
3. Create reference images
If it's your first time using loki you need to create the reference images to test your stories against. This is done with yarn loki update which by default will create a loki folder to store them in. These images should be checked into your git repository, optionally stored using git-lfs.
4. Make changes
Now it's time to make some changes to your stories or the underlying components that we want to catch with loki!
5. Run tests
Run loki again but this time in test mode with yarn loki test. You can test a subset of your configurations with a regular expression in the second argument. yarn loki test laptop will run any configuration containing the word laptop, therefore it's useful to add keywords such as platform (chrome, ios, android) to your configuration names.
6. Review changes
Loki will create screenshots of all the tested stories in the loki/current folder in addition to a visual diff placed in the loki/difference folder. You can also use a specialized diffing tool such as Kaleidoscope. Make sure the changes are correct before you continue.
7. Approve changes
If the changes were as you intended, it's time to update the reference files. The test command should output a suggested command to use that will only update the failed tests. Otherwise just use the approve command; yarn loki approve. Commit your changes along with the new reference images and repeat.