Open Handler

[tahir-tegeria]

Jest gives me a waiting about opened handlers

Giving a log to the opened handler is every file wit the import of '@testing-library/react-native'
Searching this problem for jest and the library too gives me search related to having a database open but i don't have any connection to a database and also i render just text component nothing crazy about async/await

[tahir-tegeria]

Here are my versions in package json:
"react-native": "^0.67.2",
"react": "^17.0.2",
"@testing-library/react-native": "^10.1.1",

[mdjastrzebski]

@tahir-tegeria what is the exact error message. Your screenshot contains only stacktrace.

[tahir-tegeria]

[duraz0rz]

I get the open handle warning with Jest 28. Jest 27 doesn't have the same problem.

Test:

import { render } from '@testing-library/react-native'
import React from 'react'
import { Text } from 'react-native'

describe('a test', () => {
  it('can run a test', () => {
    const { getByText } = render(<Text>Hello</Text>)

    expect(getByText('Hello')).toBeDefined()
  })
})

Test output:

 PASS  services/meow.spec.tsx
  weird test
    ✓ can run a test (19 ms)

--------------|---------|----------|---------|---------|-------------------
File          | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
--------------|---------|----------|---------|---------|-------------------
All files     |       0 |      100 |     100 |       0 |
 .eslintrc.js |       0 |      100 |     100 |       0 | 1
--------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.901 s, estimated 4 s
Ran all test suites matching /services\/meow.spec.ts/i.

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  MESSAGEPORT

    > 1 | import { render } from '@testing-library/react-native'
        | ^
      2 | import React from 'react'
      3 | import { Text } from 'react-native'
      4 |

      at node_modules/scheduler/cjs/scheduler.development.js:178:17
      at Object.<anonymous> (node_modules/scheduler/cjs/scheduler.development.js:645:5)
      at Object.<anonymous> (node_modules/scheduler/index.js:6:20)
      at node_modules/react-test-renderer/cjs/react-test-renderer.development.js:19:19
      at Object.<anonymous> (node_modules/react-test-renderer/cjs/react-test-renderer.development.js:17382:5)
      at Object.<anonymous> (node_modules/react-test-renderer/index.js:6:20)
      at Object.<anonymous> (node_modules/@testing-library/react-native/src/act.ts:1:1)
      at Object.<anonymous> (node_modules/@testing-library/react-native/src/pure.ts:1:1)
      at Object.<anonymous> (node_modules/@testing-library/react-native/src/index.ts:1:1)
      at Object.<anonymous> (services/meow.spec.tsx:1:1)

Dependencies (at least the ones that matter, I hope):

  "dependencies": {
    "@react-navigation/bottom-tabs": "^6.3.1",
    "@react-navigation/native": "^6.0.10",
    "@react-navigation/native-stack": "^6.6.2",
    "expo": "~45.0.0",
    "react": "17.0.2",
},
  "devDependencies": {
    "@babel/core": "^7.12.9",
    "@babel/plugin-proposal-async-generator-functions": "^7.18.6",
    "@babel/plugin-proposal-export-namespace-from": "^7.17.12",
    "@react-native-community/eslint-config": "^3.0.2",
    "@testing-library/dom": "^8.13.0",
    "@testing-library/jest-native": "^4.0.5",
    "@testing-library/react-hooks": "^8.0.0",
    "@testing-library/react-native": "^10.1.1",
    "@typescript-eslint/eslint-plugin": "^5.27.1",
    "@typescript-eslint/parser": "^5.27.1",
    "babel-jest": "^28.1.0",
    "isomorphic-fetch": "^3.0.0",
    "jest": "^27",
    "jest-expo": "^45.0.1",
    "jest-junit": "^13.2.0",
    "jest-mock": "^28.1.1",
    "react-test-renderer": "^17.0.2",
    "ts-jest": "^27",
    "typescript": "~4.5",
  },
  "resolutions": {
    "@types/react": "17.0.2",
    "@types/react-dom": "17.0.2",
  },

We're using the jest-expo prese, however, not the React Native one (directly, anyways).

[mdjastrzebski]

@tahir-tegeria did you manage to fix the encoutered error? Looking at the provided test, it looks like some other test file did trigger that error.

[tahir-tegeria]

Hello, well the problem was caused by the Jest library which by strange the error was throwed by react-testing-library.
The error was that jest used some port to console log and forgot to close them so it was proceeded as an opened handler.
More precisely the scheduler node-module package.
More details node-fetch/node-fetch#1479 (comment)

[afshinm]

I had the same issue, downgrading to Jest (and ts-jest) 27 fixed the issue for me.