22,881 questions
0
votes
0
answers
94
views
How do I make my Jest tests, runnable in Node.js, compatible with Bun if I am using Babel transform from browser into Node.js-compatible JavaScript? [closed]
In my project I am using this babel.config.js file to convert from browser-compatible JavaScript into Node.js-compatible JavaScript before running my Jest tests:
module.exports = {
presets: [['@...
- 870
-2
votes
0
answers
74
views
React form validation tests failing with React Testing Library – expected 2 children but received 1
I am working on a React component that implements a form with validation logic. The form includes the following fields:
Name
Email
Employee ID
Joining Date
Each field has validation rules, and ...
Advice
0
votes
0
replies
52
views
React compiler and Jest tests
I added the React Compiler to my project (basic setup from docs), and my all Jest tests failed. Would it be better to disable the React Compiler for tests, or is there a way to fix this? How to do it? ...
Best practices
0
votes
2
replies
114
views
What are best practices for unit testing with Jest in JavaScript?
I'm learning Jest and want to make sure I'm building good habits from the start. I've read the official docs but they don't really cover what's considered good practice in real projects. Specifically ...
0
votes
0
answers
53
views
Jest test suite fails with "import outside scope" from expo/src/winter/runtime.native.ts
Problem
When running Jest tests in my Expo 54 / React Native project, one test suite consistently fails with the following error:
The other tests in the suite run fine (16 passed, 4 failed all with ...
- 73
0
votes
0
answers
49
views
How do you get node inspector to pick up source files and break on breakpoints?
I am using WSL. I am following the steps in the Jest Debugging Guide. I tried running this command:
node --inspect-brk ./node_modules/jest/bin/jest.js --runInBand myTest
Then I open Google Chrome and ...
- 2,797
2
votes
1
answer
82
views
How to mock setTimeout in a Jest unit test using FakeTimers?
In my application I need to ensure that an array of Promises will be executed in the order as given in the array. Addtionally, the application shall "wait" a certain time after each Promise ...
- 651
0
votes
0
answers
26
views
SonarQube not picking up LCOV coverage in React frontend Maven multi-module build
I have a multi-module Maven project with a Java backend and a React frontend.
Backend Java coverage (JaCoCo) is reported correctly in SonarQube, but frontend JavaScript coverage is always 0%.
Project ...
0
votes
0
answers
74
views
Typing a mocked module function with a different signature in Jest
I want to mock a specific module with a specific mocked function.
Later on, I want to supply the implementation in a specific test.
I have this code:
import fs from "fs";
jest.mock("fs&...
Best practices
0
votes
1
replies
50
views
How to avoid parallel Jest tests interfering with each other's databases?
If I run integration tests sequentially (Node.js, TypeScript) they are fine, but it can be really slow, but if I make them run in parallel they edit the same database and end up causing weird bugs. Is ...
- 399
1
vote
0
answers
58
views
Jest mock not working in class singleton instance
I have created a class for connecting nats and assign it client property. application works as expected. But when I try mock the connection class for integration tests, then it does not work as ...
- 1,341
0
votes
0
answers
101
views
How to run Next.js and Jest concurrently, with an instance of Next.js already running?
I have this script in my Next.js project, where I start a Next.js server (because the tests need it) and run Jest tests using concurrently:
"test": "npm run services:up &&
...
- 78
Tooling
0
votes
2
replies
65
views
How to write tests which analyze HTTP requests made on NextJS server side?
I work on a NextJS project with Pages Router. We are using Jest for unit tests and Playwright for E2E.
The application we are making is a funnel with several steps. Each step is a form with several ...
- 623
1
vote
1
answer
72
views
Jest + Testcontainers MongoDB: Intermittent ECONNREFUSED errors running integration tests
Problem
Starting November 10th, my Jest integration tests began failing randomly with MongoDB connection errors. The tests use @testcontainers/mongodb v11.5.1 and mongodb v8.0.12.
Error:
...
- 61
0
votes
1
answer
76
views
When upgrading to React 19 and NextJS 15, jest snapshots that had header changes via `next/head` break
In our tests, we had several snapshots that included content wrapped in next/head. We had previously followed the below pattern for the mock, which allowed us to see all the header tags like meta, ...
- 3,157