Async setup of environment with Jest

Question

Before running e2e tests in Jest I need to get an authentication token from the server.

Is it possible to do this globally one and set it somehow to the glo

Answer 1

There's a CLI/config option called: setupFiles, it runs immediately before executing the test code itself.

"jest": {
  "globals": {
    "__DEV__": true,
    ...
  },
  "setupFiles": [
    "./setup.js"
  ]
}

setup.js might look something like:

(async function() {
    // const { authToken } = await fetchAuthTokens()
    global.authToken = '123'
})()

And then you can access authToken directly in each test suites (files) like beforeAll(_ => console.log(authToken)) // 123.

---

However, if you want a global setup that runs per worker(cpu core) instead of per test file (recommended by default since test suites are sandboxed). Based on current jest API constraints, you may choose to customize your test's runtime environment through the testEnvironment option. Then you need to implement a custom class that extends jsdom/node environment exposes setup/runScript/teardown api.

Example:

customEnvironment.js

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

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

  async setup() {
    await super.setup();
    const token = await someSetupTasks();
    this.global.authToken = token;
  }

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

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

my-test.js

let authToken;

beforeAll(() => {
  authToken = global.authToken;
});

Answer 2

I could find no way of skipping tests (test.skip) based on the result of an async condition. The tests determined if they were to be run before my global async condition resolved. I even tried using beforeAll and awaiting the resolution of my promise, but while in tests my condition had resolved, when the tests determined if they were to be run, the promise was unresolved and my var was undefined.

I ended up doing this with bash in scripts/isLocalCmsRunningOn3030.sh:

#!/bin/bash

if [[ $(lsof -i :3030 | grep 'node' | grep 'LISTEN') ]]; then
  echo TRUE
else
  echo FALSE
fi

package.json:

IS_CMS_RUNNING=$(scripts/isLocalCmsRunningOn3030.sh) jest

In my setupFile.js:

global.testIf = (condition) => (condition ? test : test.skip);

In my test file

  testIf(process.env.IS_CMS_RUNNING === 'TRUE')('testname', () => {
  });

Answer 3

Ini my case, I had to get the token for current session once. Here I used globalSetup property in jest config. Ref: https://jestjs.io/docs/en/configuration#globalsetup-string

My jest.config:

module.exports = {
  globalSetup: "./tests/global-setup.js",
  // ..other config... 
  globals: {
      TEST_EMAIL: 'test@test.com',
      TEST_PASSWORD: 'some_password',
  }
}

global-setup.js:

 module.exports = async function() {
  const getSessionToken = () => {
    // api call to get SessionToken
    /* return fetch() */
  }

  sessionToken = await getSessionToken();
  process.env.SESSION_TOKEN = sessionToken;
 }