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babel-jest-assertions

library0.1.0jsnpmunverified

A Babel plugin (v0.1.0) that automatically inserts `expect.assertions(n)` and `expect.hasAssertions()` into Jest test blocks by counting `expect` calls. It supports sync, async, arrow, named, and only tests, including `beforeEach`/`afterEach` blocks. Unlike manual insertion, it eliminates human error and verbosity. Current stable version is 0.1.0; no major releases planned. Minimal alternative to manual assertion count management.

testing

npm install babel-jest-assertions

github ↗package ↗

INSTALL

IMPORT

SIG · BABEL-JEST-ASSERTI

babel-jest-assertions

testingjavascriptv0.1.0

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 18–223 runs

build_error

glibc

node 18–223 runs

build_error

Code

Verified usage

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

(plugin)

✓ Add `'babel-jest-assertions'` to your `.babelrc` plugins array

✗ import babelJestAssertions from 'babel-jest-assertions'

This is a Babel plugin, not a runtime module. Use in Babel configuration only.

Shows Babel plugin configuration and how the plugin transforms a test with two assertions.

// .babelrc { "plugins": ["babel-jest-assertions"] } // test.js it('counts assertions', () => { expect(1 + 0).toBe(1); expect(0 + 1).toBe(1); }); // Transforms to: // it('counts assertions', () => { // expect.hasAssertions(); // expect.assertions(2); // expect(1 + 0).toBe(1); // expect(0 + 1).toBe(1); // });

Debug

Known issues

gotchaPlugin counts `expect` calls, not actual assertions; non-standard matcher chains may be miscounted.

fix

Manually add `expect.assertions(n)` if the count is off, or avoid complex expect chains.

affects: >=0.0.1

gotchaDoes not support dynamically computed assertion counts; `expect.assertions` uses a static integer.

fix

Use manual `expect.assertions(0)` or disable plugin for dynamic cases.

affects: >=0.0.1

breakingIn v0.1.0, support for counting `expect` in `beforeEach` and `afterEach` was added; existing tests may fail if those blocks contain assertions they didn't before.

fix

Review tests that have assertions in lifecycle hooks; adjust expected counts or add assertions.

affects: >=0.1.0

gotchaPlugin may not work with custom test wrapper functions (e.g., `describe.each`) if they don't match internal patterns.

fix

Ensure test blocks use standard `it`, `test`, `xit`, `fit`, `it.only` only.

affects: >=0.0.1

Errors

Common errors & fixes

TypeError: babel is not a function

Using plugin with Babel 7+ without updating Babel API

fix

Downgrade to Babel 6 or use the Babel 7 compatible fork of this plugin.

ReferenceError: expect is not defined

Plugin inserts `expect.assertions` but `expect` is not in scope (e.g., missing `@jest/globals` import in ESM).

fix

Add `import { expect } from '@jest/globals';` to test files or configure Jest globals properly.

The plugin "babel-jest-assertions" didn't return a function.

Using plugin string in Babel config but plugin module not installed.

fix

Run `npm install --save-dev babel-jest-assertions` and ensure it's in `node_modules`.

Upgrade

Version history

0.1.0latest on npm

Audit

Dependencies

babel-corerequiredRequired at runtime to transform code via Babel plugin API

Agent activity

17 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/mattphillips/babel-jest-assertions ↗

packagehttps://www.npmjs.com/package/babel-jest-assertions ↗