I have created one React App using npx create-react-app my-app cmd (React 17 version). Now
Well, I just tried to replace a classic
import Component from './Component'
to
const Component = React.lazy(() => import('./Component'));
and then
<React.Suspense fallback={<div>Loading.. </div>}>
<Component />
</React.Suspense>
but it throws error like
SyntaxError: Unexpected token at import(6:22)
> 6 | const Component = React.lazy(() => import('./Component'));
Can anyone help me to resolve this?
This is the code syntax
And this is the suspense component
And this is the compilation output
My package.json looks like
I'm not sure, if this fixes your issue, but maybe you can give it a try. Are you using Babel?
It says:
When using Babel, you’ll need to make sure that Babel can parse the
dynamic import syntax but is not transforming it. For that you will
need #babel/plugin-syntax-dynamic-import.
https://reactjs.org/docs/code-splitting.html#import
I've created a .babelrc file on the project root and added the content:
{
"plugins": [
"#babel/plugin-syntax-dynamic-import"
]
}
I also imported lazy in my component:
import React, { Component, lazy, useEffect, useState } from 'react';
In my project React.lazy is working fine this way.
I'm trying to make jest/enzyme tests in react
I have this test:
import React from 'react';
import { shallow } from 'enzyme';
import { mount } from 'enzyme'
import WorkOutForm from './workOutForm';
describe('WorkOutForm', () => {
it('should start a new workoutForm with empty state', () => {
const component = mount(<WorkOutForm/>)
expect(component).toMatchSnapshot();
});
})
but when i do a npm run test i receive:
src/workout/workOut.test.js ● Test suite failed to run
babel-jest: Babel ignores src/workout/workOutForm.jsx - make sure to include the file in Jest's transformIgnorePatterns as well.
I try to add this file in the package.json:
"jest": {
"transformIgnorePatterns": [
"src/workout/workOutForm.jsx"
]
}
but i'm receiving the same error.
where i have to put this?
where i have to put this?
You should not ignore jsx source files. What you need to do is convert your jsx to js using babel.
You need to use babel-preset-react. This will automatically add #babel/plugin-transform-react-jsx for the transformation.
Then put this in your .babelrc
{
"presets": ["#babel/preset-react"]
}
I have already this error and i fixed changing the code from:
"ignore": [
"./test",
"./src/assets",
"./src/stories",
"./src/.storybook"
]
To this:
"ignore": [
"./src/assets",
"./src/stories",
"./src/.storybook"
]
I remove my test folder from the .babelrc ignore prop and its works for me!
I created a new React application by create-react-app and I wanted to write a unit test to a component named "MessageBox" that I created in the application. This is the unit test that I wrote:
import MessageBox from "../MessageBox";
import { shallow } from 'enzyme';
import React from 'react';
test('message box', () => {
const app = {setState: jest.fn()};
const wrapper = shallow(<MessageBox app={app}/>);
wrapper.find('button').at(0).simulate('click');
expect(app.setState).toHaveBeenLastCalledWith({modalIsOpen: false});
});
I also added a file under 'src' folder named 'setupTests.js' with the content:
import * as enzyme from 'enzyme';
import * as Adapter from 'enzyme-adapter-react-16';
enzyme.configure({ adapter: new Adapter() });
I ran it by:
npm test
and I got the error:
Enzyme Internal Error: Enzyme expects an adapter to be configured, but
found none. To configure an adapter, you should call Enzyme.configure({ > adapter: new Adapter() })
Do you know what can solve this problem?
Add it to your test case file.
import React from 'react';
import Adapter from 'enzyme-adapter-react-16';
import { shallow, configure } from 'enzyme';
configure({adapter: new Adapter()});
test('message box', ()=> {
...
})
Also, if you don't want to import your setupTests.js file into every test file, you can place it in your package.json folder:
"jest": {
"setupTestFrameworkScriptFile": "./test/setupTests.js" }
Update:
Note: setupTestFrameworkScriptFile is deprecated in favor of setupFilesAfterEnv.
https://jestjs.io/docs/en/configuration
The file 'setupTests' has to be imported to the test file:
import MessageBox from "../MessageBox";
import { shallow } from 'enzyme';
import React from 'react';
import "../setupTests"
test('message box', ()=> {
...
})
As Priyank said, if you are using Create React App, it will pick up the configuration from src/setupTests.js.
Add:
import { configure } from 'enzyme'
import Adapter from 'enzyme-adapter-react-16'
configure({ adapter: new Adapter() })
A lot of answers are saying import setupTests.js into your test file. Or
configure enzyme adapter in each test file. Which does solve the immediate problem.
But long term, if you add a jest.config.js file to the project root. You can configure it to run a setup file on launch.
jest.config.js
module.exports = {
setupTestFrameworkScriptFile: "<rootDir>/src/setupTests.ts"
}
This tells Jest to run setupTest.ts every time it's launched.
This way if you need to add polyfills or add global mock like localstorage, you can add it to your setupTests file and its configured everywhere.
The Enzyme docs don't cover integration with Jest, so it is confusing to fuse these two together.
For me when using React with create-react-app I had to make sure the file name was correct. The file has to be src/setupTests.js with an s at the end of Tests.
Inside setupTests.js is the following:
import { configure } from "enzyme";
import Adapter from "enzyme-adapter-react-16";
configure({ adapter: new Adapter() });
When running npm run test it auto finds the setupTests.js file. There is no need to import it into each test file.
You need to use the import like this:
import Adapter from 'enzyme-adapter-react-16';
This way: (import * as Adapter from ...) returns a message "TypeError: Adapter is not a constructor."
Add import React from 'react'; to the top of your file.
You are using JSX syntax <MessageBox app={app}/>, which transpiles into React.createComponent(...). In order for this to work React variable must be defined in the scope of the file.
Try sth like this;
import React from 'react';
import App from './containers/App';
import enzyme from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
enzyme.configure({ adapter: new Adapter() });
describe('App Screen', () => {
let mountedAppScreen;
let props;
const appScreen = () => {
if (!mountedAppScreen) {
mountedAppScreen = enzyme.mount(
<App {...props} />
);
}
return mountedAppScreen;
}
it("it always renders div", () => {
const divs = appScreen().find("div");
expect(divs.length).toBeGreaterThanOrEqual(1);
});
});
Using the latest version of the libraries, I've faced the same error reported in every answer of this question. Error: TypeError: Adapter is not a constructor.
I've grouped all the necessary steps in order to proper test your ReactJS component using Enzyme (I've used Jest but it might work with Mocha as well, in that case, just switch the main test package):
1) Libraries (package.json):
"dependencies": {
"jest": "^24.6.0",
(...)
}
"devDependencies": {
"chai": "^4.2.0",
"enzyme": "^3.7.0",
"enzyme-adapter-react-16": "^1.7.0",
(...)
}
2) TEST SETUP: You can setup the Enzyme in every test. But as type_master_flash wisely suggested, you can add a script to do that. In order to do so, create a new setting in your package.json file at the same level of the sessions scripts, dependencies, etc:
Jest Version 23.x (or previous):
"devDependencies": {
(...)
},
"jest": {
"setupTestFrameworkScriptFile": "./tests.setup.js"
},
After Jest 24.0 version: According to Jest Documentation, "setupTestFrameworkScriptFile is deprecated in favor of setupFilesAfterEnv".
"devDependencies": {
(...)
},
"jest": {
"setupFilesAfterEnv": ["./tests.setup.js"]
},
This file can be anywhere you prefer and you can name it as you wish. Just remember to setup the proper file location. In the current example I've stored my file in the root of my project.
3) tests.setup.js: As I've discovered in Enzyme: TypeError: Adapter is not a constructor, the problem here is that we cannot "import '' a module with a default export". The proper way of configuring your file is:
import Enzyme from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
Enzyme.configure({ adapter: new Adapter() });
Just that and you are good to test your components.
Cheers and hope this helps.
For everyone who read this in the future, setupTestFrameworkScriptFile is deprecated in favor of setupFilesAfterEnv by the documentation, in new versions. We can add our file like this:
"setupFiles": [
"<rootDir>/src/setupTests.js"
]
I faced the same error and for some reason React wasn't picking up setupTests.js file automatically.
I created a new file called jest.config.js at the root directory and added
{ "jest": { "setupTestFrameworkScriptFile": "<rootDir>/path/to/your/file.js", } }
After this, error disappeared.
Note: Later on, I removed the jest.config.js file but it still works now.
Not sure what was actually causing the problem though!
The file configuration must be in setupFilesAfterEnv property of jest.config.js
{
...
setupFilesAfterEnv: ["<rootDir>/jest.transform.js"],
...
}
If anyone comes across this while trying to fix this after setting up Testing React Components with Jest in GatsbyJs (https://www.gatsbyjs.org/docs/testing-react-components/)
In the setup-test-env.js you make, edit it to look like this:
import "#testing-library/jest-dom/extend-expect"
import { configure } from 'enzyme'
import Adapter from 'enzyme-adapter-react-16'
configure({ adapter: new Adapter() })
Create a file named setupTests.js in the root of your project. jest will automatically look for this file before running any test suits. Add the following content to the file.
import Enzyme from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
Enzyme.configure({adapter:new Adapter()})
Note: the filename should be exactly the same.no need to import this setupTests.js file into your test files.it will work automatically
For those who use VS Code and the Jest Runner extension for a React CRA app, don't forget to configure Jest Runner to use CRA's built in script runner by setting the jest command to:
npm test -- --watchAll=false
You will get the error in topic if you forget to do that. And since you are using CRA you won't be able to configure setupFilesAfterEnv in package.json nor jest.config.js. Trying that will result in this error:
These options in your package.json Jest configuration are not currently supported by Create React App
npm i enzyme-adapter-react-16 enzyme-to-json --save-dev
Add to package.json
enter image description here
"jest": {
"collectCoverageFrom": [ "src/**/*.js", "!src/index.js" ]
};
Add two files to src folder ->
setupTests.js
tempPolyfills.js
setupTests.js :
import requestAnimationFrame from './tempPolyfills';
import { configure } from "enzyme";
import Adapter from 'enzyme-adapter-react-16';
configure({adapter: new Adapter(), disableLifecycleMethods:true});
tempPolyfills.js:
const requestAnimationFrame = global.requestAnimationFrame = callback => {
setTimeout(callback,0);
};
export default requestAnimationFrame;
in case shallow -> expect() fails in test case use toJson() :
Example :
import { shallow } from "enzyme";
import App from "./App";
import toJson from 'enzyme-to-json';
describe('App', () => {
const app = shallow(<App />);
it('renders correctly', () => {
expect(toJson(app)).toMatchSnapshot();
});
});
If you think you've otherwise setup everything correctly (e.g. have the #wojtekmaj/enzyme-adapter-react-17 for React 17 support installed), one more pitfall to check with Typescript:
Do you have
"esModuleInterop": true,
and the matching import format for the adapter?
import Adapter from '#wojtekmaj/enzyme-adapter-react-17';
import Enzyme from 'enzyme';
I'm trying to setup a jest snapshot test with redux-persist in my react-native project. I don't think its an es2015 imports problem as my test code looks something like this:
import React from "react"
import "react-native"
// Note: test renderer must be required after react-native.
import renderer from "react-test-renderer"
import App from "../App"
it("renders correctly", () => {
const app = renderer.create(<App />).toJSON()
expect(app).toMatchSnapshot()
})
I ran this exact same test before I added redux-persist and it was working.
Error thrown by jest:
● Test suite failed to run
/Users/a_050313/Documents/dev/scheduling/node_modules/redux-persist/es/integration/react.js:9
import React, { PureComponent } from 'react'; // eslint-disable-line import/no-unresolved
^^^^^^
SyntaxError: Unexpected token import
1 | import React, { Component } from "react"
2 | import { Provider } from "react-redux"
> 3 | import { PersistGate } from "redux-persist/es/integration/react"
4 |
5 | import "./__debug__/ReactotronConfig" // Run Reactron Tools config
6 |
at ScriptTransformer._transformAndBuildScript (node_modules/jest-runtime/build/script_transformer.js:318:17)
at Object.<anonymous> (App.js:3:13)
at Object.<anonymous> (__tests__/App.js:7:10)`
The error was related to es2015 imports but It is on jest end. By default jest only transpiles project code and react-native code. So the added libs which aren't already transpilled would error out by jest.
(as mentioned on jest docs)
By default the jest-react-native preset only processes the project's own source files and react-native
Solution provided on the official docs seems a bit hacky but thats the only thing I found:
Add following in your package.json jest: { } section or in jest.config.js file.
"transformIgnorePatterns": [
"node_modules/(?!(react-native|my-project|redux-persist)/)"
]
where the bit redux-persist is the thing that solves the problem. If you have problem with other libs just add their names. My list looks something like this:
"jest": {
"preset": "react-native",
"transformIgnorePatterns": [
"node_modules/(?!(react-native|my-project|redux-persist|react-native-linear-gradient|react-native-vector-icons|react-navigation)/)"
]
}
Additional Note just for redux-persist if you import PersistGate from
import { PersistGate } from "redux-persist/lib/integration/react"
instead
import { PersistGate } from "redux-persist/es/integration/react"
(reference)
you'll get the compiled version but for other libs still you got to this the above mentioned solution.
I have a simple shallow test.
import React from 'react';
import { shallow } from 'enzyme';
import Layout from '../containers/'
it('renders without crashing', () => {
shallow(<Layout />);
});
Upon adding firebase.storage() functionality to my app (not in Layout.jsx directly but in the child of children of Layout) - i am now failing this simple test. I was under the impression that a shallow render here would be... well, shallow... no?
It should be noted that all of my firebase components work just fine and i'm not getting any errors anywhere other than this failing test.
I have tried bringing in import 'firebase/storage' but this doesn't work. Ideas?
I overwrote the test script in package.json to react-scripts test --env=jsdom --browser and it worked.