Allow globalSetup to pass variables to test suite and globalTeardown

🚀 Feature Proposal

Currently, there is no way (not that I know of) to pass any variable from the globalSetup in order to be able to either use it in the tests or to clear it in the globalTeardown.

Motivation

Imagine the following test case: I am writing acceptance tests for a logger, that can send the logs to a web server through HTTP. In the test suite, I would like to create a simple HTTP server in the globalSetup and be able to use it in the test suite without the need to specify an own environment (jest-environment-node) that runs for every test file, unlike the globalSetup that runs once. Then after the tests are done, I would like to be able to close the server in globalTeardown, but currently, there is no way to pass a reference to it.

Example

// globalSetup.js
const createHttpServer = require("./servers/http-server");

module.exports = async () => {
 const http = createHttpServer(5000);
 return { http };
};

// test/spec file
describe("sample-test", () => {
  it("send a request", (next) => {
   const logger = new Logger({ method: "POST", url: "http://localhost:5000" })
   // setup could be exposed as global variable
   global.setup.http.on("request", (req, res) => {
     // ... simplified
     expect(body).toBe("xxx")
     next()
    })
    logger.log("xxx")
  })
})

// globalTeardown.js
module.exports = async (setup) => {
  await promisify(setup.http.close)
};

Pitch

Why does this feature belong in the Jest core platform?

Current global handlers use cases are too limited in order to be useful.

[SimenB]

Workaround for now is just to assign to a global in setup.

I still think some limited (e.g. json serialized) injection from setup into tests make sense (although that won’t cover what OP wants), and we could inject that into teardown as well (not serialized in that case).

[github-actions[bot]]

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