globalSetup is executed in different context than tests

Currently if globalSetup is used to asynchronously prepare something, and then the same file is imported in tests it results in two separate module instances.

Repo to reproduce: https://github.com/kirill-konshin/jest-globalsetup-bug

// jest.globalSetup.js
const doSomethingAsync = () => new Promise(resolve => resolve(Math.random()));
let browser;
const globalSetup = () => doSomethingAsync().then((res) => {
    browser = res;
    console.log('Setup', module.exports.getBrowser());
});
module.exports = globalSetup;
module.exports.getBrowser = () => browser;

// jest.globalTeardown.js
const setup = require('./globalSetup');
module.exports = () => {
    console.log('Teardown', setup.getBrowser());
};

// one of test files
const setup = require('./globalSetup');
describe('browser test', () => {
  it('opens a page', async () => {
      console.log('Test', setup.getBrowser());
  });
});

After npm test console shows that test had it undefined while setup and teardown both printed same value:

> jest-bug@1.0.0 test /Users/dis/Sites/jest-bug
> NODE_ENV=test jest

Determining test suites to run...
Setup 0.23915022164799082
 PASS  ./index.test.js
  browser test
    ✓ opens a page (11ms)

  console.log index.test.js:4
    Test undefined

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.992s, estimated 1s
Ran all test suites.
Teardown 0.23915022164799082

In my use case inside doSomethingAsync an instance of puppeteer browser would be created.

AFAIK there is no other way to do something before all tests and after all tests.

NPX:

LMRC6785:jest-bug dis$ npx envinfo --preset jest
npx: installed 1 in 1.526s

  System:
    OS: macOS High Sierra 10.13.4
    CPU: x64 Intel(R) Core(TM) i7-4980HQ CPU @ 2.80GHz
  Binaries:
    Node: 9.4.0 - /usr/local/bin/node
    Yarn: yarn install v0.24.6
info No lockfile found.
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
success Saved lockfile.
Done in 5.90s. - ~/.yarn/bin/yarn
    npm: 5.6.0 - /usr/local/bin/npm
  npmPackages:
    jest: 22.4.3 => 22.4.3 

[SimenB]

This is by design - every single test file gets its own context. If you want to access something set up in a globalSetup you need to do something like what https://github.com/smooth-code/jest-puppeteer is doing.

Importing your globalSetup from a file is not supported (and it won’t be).

If you have more questions about this topic, we recommend using StackOverflow or our discord channel.

If you think anything can be clarified in the docs, a PR is most welcome!

[SimenB]

Tests do not share the same context, each individual test file has their own. global{Setup,Teardown} is not part of a single test’s context (otherwise it’d have to run multiple times instead of exactly once), and it’s impossible for it to be.

If you want to run setup a single time (typically starting up some long-running service), use globalSetup. If you need something to run in context before each test, use setupFiles