问题
I have a React application (not using Create React App) built using TypeScript, Jest, Webpack, and Babel. When trying to run "yarn jest", I get the following error:
I have tried removing all packages and re-adding them. It does not resolve this. I have looked at similar questions and documentation and am still misunderstanding something. I went so far as to follow another guide for setting up this environment from scratch and still received this issue with my code.
Dependencies include...
"dependencies": {
"@babel/plugin-transform-runtime": "^7.6.2",
"@babel/polyfill": "^7.6.0",
"babel-jest": "^24.9.0",
"react": "^16.8.6",
"react-dom": "^16.8.6",
"react-test-renderer": "^16.11.0",
"source-map-loader": "^0.2.4"
},
"devDependencies": {
"@babel/core": "^7.6.0",
"@babel/preset-env": "^7.6.0",
"@babel/preset-react": "^7.0.0",
"@types/enzyme": "^3.9.2",
"@types/enzyme-adapter-react-16": "^1.0.5",
"@types/jest": "^24.0.13",
The component's import lines...
import * as React from "react";
import { BrowserRouter as Router, Route, Switch } from "react-router-dom";
import HomePage from "./components/pages";
import {
Footer,
Header,
Navigation,
} from "./components/shared";
The test file....
import * as React from "react";
import * as renderer from "react-test-renderer";
import App from "../App";
it("Renders the Footer correctly", () => {
const tree = renderer
.create(<App />)
.toJSON();
expect(tree).toMatchSnapshot();
});
I expected to be able to use named imports in my components without my tests blowing up. It appears to fix the issue if I only use default imports through my solution, but I would prefer to not go that route.
回答1:
Solution: my named imports were coming from index.js files and I believe ts-jest needed them as index.ts files (I'm using Typescript). If anyone else runs into this error, couldn't hurt to check if you derped your file extensions.
I wasted a lot of time on this, unfortunately, but I learned a lot about webpack configurations and Babel.
回答2:
For future references,
I solved the problem by using below jest config, after reading Logan Shoemaker's answer.
module.exports = {
verbose: true,
setupFilesAfterEnv: ["<rootDir>src/setupTests.ts"],
moduleFileExtensions: ["js", "jsx", "ts", "tsx"],
moduleDirectories: ["node_modules", "src"],
moduleNameMapper: {
"\\.(css|less|scss)$": "identity-obj-proxy"
},
transform: {
'^.+\\.(ts|tsx)?$': 'ts-jest',
"^.+\\.(js|jsx)$": "babel-jest",
"\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/__mocks__/file.js",
}
};
回答3:
Use Babel to transpile those JS Modules and you'll be able to write your tests with es6.
Install Babel/preset-env
npm i -D @babel/preset-env
Create a babel configuration file with the preset
//babel.config.js
module.exports = {presets: ['@babel/preset-env']}
来源:https://stackoverflow.com/questions/58613492/how-to-resolve-cannot-use-import-statement-outside-a-module-in-jest