I'm trying to contribute to a testing library. The library should provide a wrapper for react-test-renderer like react-native-testing-library does.
In order to see if my code worked I wrote a simple unit test using the code I wrote for the library. Since this was the first test for React Native I added react-native as a dev dependency together with metro-react-native-babel-preset. Furthermore, I added the preset to babel.
{
"presets": [
[
"env",
{
"targets": {
"browsers": ["last 2 versions", "safari >= 7"]
}
}
],
"react",
"module:metro-react-native-babel-preset"
]
}
The library does its assertions using tape.
Now, every test (npm test) throws the error:
> node -r babel-register -r babel-polyfill source/test
/path/to/node_modules/babel-core/lib/transformation/file/options/option-manager.js:328
throw e;
^
Error: Couldn't find preset "module:metro-react-native-babel-preset" relative to directory
When I remove the preset from the babel config, I get the error:
(node:1841) UnhandledPromiseRejectionWarning: Error: Cannot find module 'View'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:581:15)
at Function.Module._load (internal/modules/cjs/loader.js:507:25)
at Module.require (internal/modules/cjs/loader.js:637:17)
at require (internal/modules/cjs/helpers.js:22:18)
at Object.get View [as View] (/path/to/node_modules/react-native/Libraries/react-native/react-native-implementation.js:165:12)
at _callee7$ (/path/to/source/test.js:110:6)
at tryCatch (/path/to/node_modules/babel-polyfill/node_modules/regenerator-runtime/runtime.js:65:40)
at Generator.invoke [as _invoke] (/path/to/node_modules/babel-polyfill/node_modules/regenerator-runtime/runtime.js:303:22)
at Generator.prototype.(anonymous function) [as next] (/path/to/node_modules/babel-polyfill/node_modules/regenerator-runtime/runtime.js:117:21)
at step (/path/to/source/test.js:27:191)
(node:1841) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)
(node:1841) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
not ok 10 test exited without ending
---
operator: fail
at: process.<anonymous> (/path/to/node_modules/tape/index.js:90:19)
stack: |-
Error: test exited without ending
at Test.assert [as _assert] (/path/to/node_modules/tape/lib/test.js:226:54)
at Test.bound [as _assert] (/path/to/node_modules/tape/lib/test.js:77:32)
at Test.fail (/path/to/node_modules/tape/lib/test.js:319:10)
at Test.bound [as fail] (/path/to/node_modules/tape/lib/test.js:77:32)
at Test._exit (/path/to/node_modules/tape/lib/test.js:191:14)
at Test.bound (/path/to/node_modules/tape/lib/test.js:77:32)
at process.<anonymous> (/path/to/node_modules/tape/index.js:90:19)
at process.emit (events.js:194:15)
How can I get React Native components to run in my test in a library (and outside of an expo init or react-native init project?
EDIT: I found out that the repo is using Babel 6, which is why the metro preset doesn't seem to work. So I exchanged it for babel-preset-react-native and now I'm back to the initial error that View can't be found.
EDIT 2: package.json
"scripts": {
"lint": "eslint source && echo 'Lint complete.'",
"typecheck": "npx -p typescript tsc --rootDir . source/test.js --allowJs --checkJs --noEmit --lib es6 --jsx react && echo 'TypeScript check complete.'",
"ts": "npm run -s typecheck",
"test": "node -r babel-register -r babel-polyfill source/test",
"watch": "watch 'clear && npm run -s test | tap-nirvana && npm run -s lint && npm run -s typecheck' source",
"precommit": "npm run -s test && npm run -s lint && npm run -s typecheck"
},
"devDependencies": {
"@types/node": "10.12.27",
"babel-cli": "6.26.0",
"babel-eslint": "10.0.1",
"babel-preset-env": "1.7.0",
"babel-preset-react": "6.24.1",
"babel-preset-react-native": "4.0.1",
"babel-register": "6.26.0",
"eslint": "5.14.1",
"eslint-plugin-react": "7.12.4",
"react": "16.8.3",
"react-native": "0.58.5",
"tap-nirvana": "1.1.0",
"typescript": "3.3.3333",
"watch": "1.0.2"
},
"dependencies": {
"cheerio": "1.0.0-rc.2",
"esm": "3.2.6",
"react-dom": "16.8.3",
"react-test-renderer": "16.8.3",
"tape": "4.10.1"
}
EDIT 3:
Sorry, apparently I didn't include my code, even though it is a helpful for solving this problem. It's pretty basic. I'm just trying to render a <View /> using ReactTestRenderer.
import TestRenderer from 'react-test-renderer';
import { Text, View } from 'react-native';
import { describe } from 'riteway';
describe('renderReactNativeComponent', async assert => {
const text = 'Foo';
const component = TestRenderer.create(
<View>
<Text>{text}</Text>
</View>
);
console.log(Text);
assert({
given: 'A React Native component',
should: 'return a working react test renderer instance',
actual: component.findByType('text'),
expected: text
});
});
According to the docs, "Starting from react-native version 0.38, a Jest setup is included by default when running react-native init.".
And
"react-native ships with a Jest preset, so the jest.preset field of your package.json should point to react-native. The preset is a node environment that mimics the environment of a React Native app. Because it doesn't load any DOM or browser APIs, it greatly improves Jest's startup time."
The point is that Jest is supposed to work with React-Native, and riteway isn't. When you run react-native init the following dependency is added: "jest-react-native". And a jest preset is added to package.json:
"jest": {
"preset": "react-native"
}
Apparently there isn't any preset for riteway yet.