1# Generating new Jest Mocks 2 3This document will guide you through the process of generating new Jest Mocks for `packages/jest-expo` module using `apps/jest-expo-mock-generator`. 4 5# **Why** 6 7We provide some mocks of our native methods which are generated by traversing all the modules and its methods and making a configuration of all those methods with the number of arguments etc. 8 9# **How** 10 111. In your terminal, go to `apps/jest-expo-mock-generator` 12 - run `yarn` to ensure the dependencies are installed 13 - run `expo start` to start the Expo server 14 152. Open the **Expo Go** project on `iOS` by opening `ios/Exponent.xcworkspace` 16 - run the project on a simulator or a device 17 183. Open `jest-expo-mock-generator` in the running **Expo Go** app 19 204. After the app is finished opening, in the terminal, where the Expo server is running, you should see a big chunk of text wrapped with 21 22 `------------------------------COPY THE TEXT BELOW------------------------------` 23 24 and 25 26 `------------------------------END OF TEXT TO COPY------------------------------` 27 28 lines. Select and copy the text from between those lines. 29 30https://user-images.githubusercontent.com/379606/120577838-b4964a80-c3d9-11eb-93db-aba3ea9eef41.mp4 31 325. Stop the Expo server running in `apps/jest-expo-mock-generator`, started in step 1. 33 346. Paste the copied text into `packages/jest-expo/src/preset/expoModules.js`. 35 367. In the terminal, go into `packages/jest-expo`. 37 388. Run `yarn prettier src/preset/expoModules.js --write`. 39 409. Commit the changes. Bonus points for not modifying mock values (like `deviceYearClass`), which will be different if you use a test device different than the one used before. 41