React-native-lib-test NPM

ANNOUNCEMENT

DO NOT MODIFY OR CHANGE THE CODE BEFORE CONFIRMED BY DOOBOOLAB. THIS REPOSITORY IS USED IN DOOBOO-CLI.

React Native TS Boilerplate

Specification

Gain points

1. Sample of context-api with `react-hook` (`useContext`).
2. Know how to structure react native app with typescript.
3. Know how to navigate between screens with `react-navigation`.
4. Know how to write test code with `testing-library`.
5. Know how to `lint` your project with `eslint` for both `ts` and maybe some `js`.
6. Know how to localize your project.

INSTALL

npm install && npm start
// or
yarn && yarn start

Structures

app/
├─ .doobooo // necessary if using dooboo-cli
├─ assets
│  └─ icons // app icons
│  └─ images // app images like background images
├─ node_modules/
├─ src/
│  └─ apis
│  └─ components
│     └─ navigations
│     └─ screen
│     └─ shared
│  └─ providers
│  └─ utils
│  └─ App.tsx
├─ test/
├─ .buckconfig
├─ .flowconfig
├─ .gitattributes
├─ .gitignore
├─ .watchmanconfig
├─ app.json
├─ babel.config.js
├─ index.js
├─ jest.config.js
├─ package.json
├─ README.md
├─ STRINGS.js
├─ tsconfig.json
└─ eslint.json

Running the project

Running the project is as simple as running

npm run start

This runs the start script specified in our package.json, and will spawn off a server which reloads the page as we save our files. Typically the server runs at http://localhost:8080, but should be automatically opened for you.

Testing the project

Testing is also just a command away:

npm test

Result

> jest -u

 PASS  src/components/shared/__tests__/Button.test.tsx
 PASS  src/components/screen/__tests__/Intro.test.tsx
 › 2 snapshots written.

Snapshot Summary
 › 2 snapshots written in 1 test suite.

Test Suites: 2 passed, 2 total
Tests:       5 passed, 5 total
Snapshots:   2 added, 4 passed, 6 total
Time:        3.055s, estimated 6s
Ran all test suites

Writing tests with Jest

We've created test examples with jest-ts in src/components/screen/__tests__ and src/components/shared/__tests__. Since react is component oriented, we've designed to focus on writing test in same level of directory with component. You can simply run npm test to test if it succeeds and look more closer opening the source.

Vscode prettier and eslint setup

"eslint.enable": true,
"eslint.validate": [
    "javascript",
    "javascriptreact",
    "typescript",
    "typescriptreact"
],
// prettier extension setting
"editor.formatOnSave": true,
"[javascript]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
},
"[javascriptreact]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
},
"[typescript]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
},
"[typescriptreact]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode"
},
"prettier.singleQuote": true,
"prettier.trailingComma": "all",
"prettier.arrowParens": "always",
"prettier.jsxSingleQuote": true

Using Context Api

Whenever you add your own Context provider you can add it to providers/ and use it inside of providers/index.tsx

Splitting provider is preferred

// Add providers here
const AllProviders = ({ isTest, children }: Props): React.ReactElement => {
  return (
    <AppProvider>
      <ThemeProvider initialThemeType={isTest ? ThemeType.LIGHT : undefined}>
        {children}
      </ThemeProvider>
    </AppProvider>
  );
};

The AllProviders is being used at App.tsx and test files easily

// App.tsx
function App(): React.ReactElement {
  return (
    <AllProviders>
      <SwitchNavigator />
    </AllProviders>
  );
}

// test files
const component = (props): React.ReactElement => {
  return (
    <AllProviders isTest>
      <Intro {...props} />
    </AllProviders>
  );
};

using consistent theme(ThemeType.LIGHT as default) explicitly is encouraged in testing for avoiding unexpected snapshot test errors

Localization

We've defined Localization strings in STRINGS.js which is in root dir. We used react-native-localization pacakage for this one.

import LocalizedStrings from 'react-native-localization';

const strings = new LocalizedStrings({
  en: {
    LOGIN: 'Login',
  },
  kr: {
    LOGIN: '로그인',
  },
});

export {
  strings,
};

Fixed jest setup by adding following in jestSetup.

import { NativeModules } from 'react-native';

/**
 * monkey patching the locale to avoid the error:
 * Something went wrong initializing the native ReactLocalization module
 * https://gist.github.com/MoOx/08b465c3eac9e36e683929532472d1e0
 */

NativeModules.ReactLocalization = {
  language: 'en_US',
};