Registry / testing / jest-useragent-mock

jest-useragent-mock

library0.1.1jsnpmunverified

jest-useragent-mock is a lightweight utility designed to facilitate the mocking of `navigator.userAgent` within Jest unit tests. It provides simple functions, `mockUserAgent` and `clear`, to set and reset the browser's user-agent string, making it easier to test browser-specific logic or user-agent dependent features. The current stable version is 0.1.1. Given its specific scope and low version, it operates on an infrequent release cadence, appearing to be in a maintenance state with no recent updates since its initial release. Its key differentiator is its singular focus on `navigator.userAgent` mocking, directly integrating with Jest's setup files for global application across test suites, distinguishing it from broader mocking libraries by offering a specialized, minimalist solution.

testing

npm install jest-useragent-mock

github ↗package ↗

INSTALL

IMPORT

SIG · JEST-USERAGENT-MOC

jest-useragent-mock

testingjavascriptv0.1.1

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

mockUserAgent

✓ import { mockUserAgent } from 'jest-useragent-mock';

✗ const { mockUserAgent } = require('jest-useragent-mock');

The library primarily uses ES modules. While CommonJS might technically work, the recommended approach, especially with TypeScript, is ES module imports.

clear

✓ import { clear } from 'jest-useragent-mock';

✗ import clear from 'jest-useragent-mock';

`clear` is a named export, not a default export. Ensure correct destructuring from the module.

Demonstrates how to set up `jest-useragent-mock` with Jest's `setupFiles`, mock `navigator.userAgent` for specific tests, and ensure cleanup after each test.

import { clear, mockUserAgent } from 'jest-useragent-mock'; // jest.config.js should include setupFiles: ["jest-useragent-mock"] describe('User-Agent Dependent Feature', () => { afterEach(() => { // It's crucial to clear the mock after each test to prevent side effects // and ensure isolation between test cases. clear(); }); it('should detect a Chrome user agent correctly', () => { const chromeAgent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.75 Safari/537.36'; mockUserAgent(chromeAgent); expect(window.navigator.userAgent).toEqual(chromeAgent); // Example of browser detection logic (simplistic) const isChrome = window.navigator.userAgent.includes('Chrome') && !window.navigator.userAgent.includes('Edg'); expect(isChrome).toBe(true); }); it('should detect a Firefox user agent correctly', () => { const firefoxAgent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:99.0) Gecko/20100101 Firefox/99.0'; mockUserAgent(firefoxAgent); expect(window.navigator.userAgent).toEqual(firefoxAgent); const isFirefox = window.navigator.userAgent.includes('Firefox'); expect(isFirefox).toBe(true); }); });

Debug

Known issues

gotchaFailing to call `clear()` after each test can lead to global state pollution. Mocks will persist across tests, causing unpredictable behavior and flaky test results.

fix

Always include `afterEach(() => { clear(); });` in your test files or a shared setup script to reset the user agent mock.

affects: >=0.1.0

breakingThis package is explicitly designed for Jest and relies on a browser-like environment (e.g., `testEnvironment: 'jsdom'`). Using it in a Node.js-only Jest environment (`testEnvironment: 'node'`) will result in `window` or `navigator` being undefined.

fix

Ensure your Jest configuration sets `testEnvironment: 'jsdom'` for test files that interact with browser globals like `window.navigator`.

affects: >=0.1.0

gotchaThe package currently resides at a low version (0.1.1) and has seen no updates in several years. While functional for its stated purpose, the lack of active development means no new features, bug fixes, or compatibility updates for newer browser/Node.js versions or Jest major releases should be expected. Use with caution for long-term projects.

fix

Consider pinning the package version to avoid unexpected dependency resolution issues. For projects requiring active maintenance or advanced features, evaluate alternative, more actively developed mocking solutions or custom Jest setups.

affects: <=0.1.1

gotchaThe library works by modifying `window.navigator.userAgent` directly. If other parts of your test setup or application code also modify this global property, conflicts can occur. Ensure `jest-useragent-mock` is the sole modifier in your test environment for this specific property.

fix

Review your test suite and application code for other direct manipulations of `window.navigator.userAgent`. Isolate its usage to `jest-useragent-mock` within your Jest tests.

affects: >=0.1.0

Errors

Common errors & fixes

ReferenceError: window is not defined

Jest is running tests in a Node.js environment (`testEnvironment: 'node'`) which lacks browser globals like `window`.

fix

Configure Jest to use a browser-like environment by adding `testEnvironment: 'jsdom'` to your `jest.config.js` or within the test file's docblock.

TypeError: Cannot read properties of undefined (reading 'userAgent')

`navigator` or `window.navigator` is undefined, typically due to the same reason as 'window is not defined'.

fix

Set `testEnvironment: 'jsdom'` in your Jest configuration.

Expected: 'test-agent' Received: 'default-agent' (or an unexpected user agent string)

The mock set by `mockUserAgent` is not being applied, or a previous mock was not cleared, leading to an incorrect `userAgent` value.

fix

Ensure `jest-useragent-mock` is correctly listed in `setupFiles` in `jest.config.js` and that `clear()` is called in an `afterEach` hook.

Upgrade

Version history

0.1.1latest on npm

Audit

Dependencies

jestrequiredThis package is a Jest test utility and requires Jest to run and function correctly. It relies on Jest's test environment and global setup capabilities.

Agent activity

9 hits · last 30 days

node

Amazon

Resources

githubhttps://github.com/ariesjia/jest-useragent-mock ↗

packagehttps://www.npmjs.com/package/jest-useragent-mock ↗