How to write simple Jest preset

Question

How to write own Jest preset with common beforeAll and afterAll?

I'm quite confused, seems that there is no related documentation.

Answer 1

There is the environment that you can extend this way:

JEST config:

module.exports = {
    testEnvironment: './suites/future/jest.myEnv.js',
};

The jest.myEnv.js:

const NodeEnvironment = require('jest-environment-node');

const start = async () => {
    console.log('START');
};

const stop = async () => {
    console.log('STOP');
};

class TestEnvironment extends NodeEnvironment {
    constructor(config) {
        super(config);
    }

    async setup() {
        await super.setup();
        await start();
    }

    async teardown() {
        await stop();
        await super.teardown();
    }

    runScript(script) {
        return super.runScript(script);
    }
}

module.exports = TestEnvironment;