Test ES6 modules with Jest [duplicate] - unit-testing

Question

This question already has answers here:
Does Jest support ES6 import/export?
(10 answers)
Closed 11 months ago.
How to test ES6 modules with Jest.
Example:
sum.js
const sum = function (a, b) {
return a + b;
}
export default sum;
sum.test.js
import sum from './sum';
test('adds 1 + 2 to equal 3', () => {
expect(sum(1, 2)).toBe(3);
});

Answer 1

The only requirement is to config your test environment to Babel, and add the es2015 transform plugin:
Step 1:
Add your test environment to .babelrc in the root of your project:
{
"env": {
"test": {
"plugins": ["#babel/plugin-transform-modules-commonjs"]
}
}
}
Step 2:
Install the es2015 transform plugin:
npm install --save-dev #babel/plugin-transform-modules-commonjs
And that's it. Jest will enable compilation from ES modules to CommonJS automatically, without having to inform additional options to your jest property inside package.json.

Answer 2

The solutions above didn't work for me. I was able to solve with this:
yarn add --dev babel-jest #babel/core #babel/preset-env #babel/preset-typescript
babel.config.js
module.exports = {
presets: [
[
'#babel/preset-env',
{
targets: {
node: 'current',
},
},
],
'#babel/preset-typescript'
],
};
where I'm using typescript.
Reference.