afterAll fails to close Express server and leaves open handles

[johncmunson]

🐛 Bug Report

Jest fails to close the Express server in the afterAll hook and leaves an open handle. After running into this issue with both supertest and axiosist, and then trying to roll my own solution, I'm starting to think this is actually an issue with Jest.

• relevant supertest github issue
• relevant axiosist github issue
• relevant stackoverflow question

To Reproduce

1. Clone this repo
2. Checkout the jest-github-issue branch
3. Run npm install
4. Create .env file containing NODE_ENV=test
5. Run npm test

Expected behavior

Jest should close the Express server in the afterAll hook and not leave any open handles

Link to repl or repo (highly encouraged)

https://github.com/johncmunson/todo-api
Be sure to checkout the jest-github-issue branch

envinfo

System:
    OS: macOS Mojave 10.14.6
    CPU: (8) x64 Intel(R) Core(TM) i7-4870HQ CPU @ 2.50GHz
  Binaries:
    Node: 10.16.3 - ~/n/bin/node
    Yarn: 1.19.1 - /usr/local/bin/yarn
    npm: 6.9.0 - ~/n/bin/npm
  npmPackages:
    jest: ^24.9.0 => 24.9.0

[johncmunson]

After following @SimenB's advice here, I converted my beforeAll and afterAll hooks to use done instead of being async. His advice did not work, and the issue is not resolved. Jest still leaves open handles.

const { createServer } = require('http')
let axios = require('axios')
const getPort = require('get-port')
const { app } = require('../../index')
const { Todo } = require('../../models')

let server

beforeAll((done) => {
  getPort()
    .then(port => {
      axios = axios.create({ baseURL: `http://localhost:${port}` })
      server = createServer(app)
      server.listen(port, done)
    })
})

afterAll((done) => {
  server.close(done)
})

describe('GET /todos', () => {
  it('returns a list of todos', async () => {
    const { data: todos } = await axios.get('/todos')
    todos.forEach(todo => {
      expect(() => Todo.fromJson(todo)).not.toThrow()
    })
  })
})

[SimenB]

This is because knex has a connection pool. This diff will exit the process correctly, but probably also make it so you can't reuse your db in other tests. You should startup and close a db connection in every test, not have a shared singleton.

diff --git i/tests/integration/todos.test.js w/tests/integration/todos.test.js
index d5e79d5..a37475e 100644
--- i/tests/integration/todos.test.js
+++ w/tests/integration/todos.test.js
@@ -2,6 +2,7 @@ let axios = require('axios')
 const getPort = require('get-port')
 const { app } = require('../../index')
 const { Todo } = require('../../models')
+const knex = require('../../db')
 
 let server
 
@@ -13,6 +14,7 @@ beforeAll(async () => {
 
 afterAll(() => {
   server.close()
+  knex.destroy()
 })
 
 describe('GET /todos', () => {

Note that you should probably wait for both close and destroy to invoke their callbacks.

We have a guide for mongodb - I'm sure knex is similar enough that it can be applied https://jestjs.io/docs/en/mongodb

EDIT: That guide is just a preset, not as general as I thought it was. There is an example in this repo though, which has all the code for it: https://github.com/facebook/jest/tree/77c3ceedfd61ddc841e11fec7b76e540924d3e60/examples/mongodb. Maybe use that as basis to create a similar preset for knex? Dunno 🙂

[johncmunson]

@SimenB thank you for making me aware of the testEnvironment config property. Perhaps drawing more attention to this in the docs would be helpful, because unintuitively it would seem that in many cases globalSetup and globalTeardown are not sufficient on their own. I will make another comment with my solution once I've got it working. Perhaps it can be the basis for a new knex example repo in the docs, similar to the mongo example.

Update:
As promised, here is my new and improved Jest setup.
https://github.com/johncmunson/todo-api/tree/jest-github-issue-resolved

[SimenB]

Yeah, sounds good! Happy to take any other doc updates to make it clearer as well

[johncmunson]

On a sidenote, jest-circus looks absolutely fascinating. The ability to act on any one of these Jest events looks very powerful!

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