I was trying to implement the example shown in Jest website: Getting started with Jest.
While running npm test
on I was getting the following error:
Based on this github issue: @jest-environment node not working in v22,
I updated the sum.test.js
as:
/**
* @jest-environment node
*/
const sum = require('./sum');
test('adding sum function', () => {
expect(sum(234,4)).toBe(238);
})
Now I got rid of the TypeError: environment.setup is not a function
.
Output:
PASS src/sum.test.js
✓ adding sum function (2ms)
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 0.438s
Ran all test suites.
Reading several answers, today I recreated the scenario.
Step 1:
I created a new project using create-react-app
.
The command: create-react-app demo-app
package.json
file:
{
"name": "demo-app",
"version": "0.1.0",
"private": true,
"dependencies": {
"react": "^16.3.2",
"react-dom": "^16.3.2",
"react-scripts": "1.1.4"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test --env=jsdom",
"eject": "react-scripts eject"
}
}
This file shows that jest
is not included in the dependencies.
Step 2:
I included sum.js
and sum.test.js
files in src
folder as shown in the official getting started guide.
sum.js
:
function sum(a, b) {
return a + b;
}
module.exports = sum;
sum.test.js
:
const sum = require('./sum');
test('adds 1 + 2 to equal 3', () => {
expect(sum(1, 2)).toBe(3);
});
Step 3:
I ran yarn test
command without including jest
in package.json
file.
So, this test command uses react-scripts test --env=jsdom
as shown in package.json
.
Output of the test:
PASS src/sum.test.js
PASS src/App.test.js
Test Suites: 2 passed, 2 total
Tests: 2 passed, 2 total
Snapshots: 0 total
Time: 0.594s, estimated 1s
Ran all test suites related to changed files.
Step 4:
I updated the package.json
file to use jest
as test script:
{
"name": "demo-app",
"version": "0.1.0",
"private": true,
"dependencies": {
"react": "^16.3.2",
"react-dom": "^16.3.2",
"react-scripts": "1.1.4"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "jest",
"eject": "react-scripts eject"
}
}
Again I ran yarn test
and the output is:
$ jest
PASS src/sum.test.js
FAIL src/App.test.js
● Test suite failed to run
/<PATH>/demo-app/src/App.test.js: Unexpected token (7:18)
5 | it('renders without crashing', () => {
6 | const div = document.createElement('div');
> 7 | ReactDOM.render(<App />, div);
| ^
8 | ReactDOM.unmountComponentAtNode(div);
9 | });
10 |
Test Suites: 1 failed, 1 passed, 2 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 0.645s, estimated 1s
Ran all test suites.
jest
using yarn add --dev jest
or npm install --save-dev jest
if you use create-react-app
command. jest
is included in node-modules
of the project if you use create-react-app
.From official Jest documentation:
Setup with Create React App
If you are just getting started with React, we recommend using Create React App. It is ready to use and ships with Jest! You don't need to do any extra steps for setup, and can head straight to the next section.
package.json
file { look at this issue }. Keep the default "test": "react-scripts test --env=jsdom",
in that.