react-native-fast-jest
Run testing 3x faster than babel-jest!
Internally using @swc/jest
| babel-jest (61s) | react-native-fast-jest (23s) |
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Installation
npm i --save-dev react-native-fast-jest
Configuration
- You need to configure
.swcrclike below.
{
"jsc": {
"parser": {
"syntax": "typescript",
"jsx": true,
"tsx": true,
"dynamicImport": false,
"privateMethod": false,
"functionBind": false,
"exportDefaultFrom": false,
"exportNamespaceFrom": false,
"decorators": false,
"decoratorsBeforeExport": false,
"topLevelAwait": false,
"importMeta": false,
"preserveAllComments": false
},
"transform": null,
"target": "es5",
"loose": true,
"externalHelpers": false,
"keepClassNames": false
},
"isModule": true
}- Configure jest config trasform
transform: {
'^.+\\.(t|j)sx?$': 'react-native-fast-jest',
},I have error when jest.spyOn
TypeError: Cannot redefine property or TypeError: Cannot read properties of undefined
You need to do mock as a esModule
jest.mock('./path_to_spy', () => {
return {
__esModule: true, // <- Important!
...jest.requireActual('./path_to_spy'),
};
});