power-assert

library1.6.1jsnpmunverified

Power Assert in JavaScript v1.6.1 (stable, released 2017). Provides descriptive assertion messages via the standard Node.js assert interface. No API is the best API – you only need assert(any_expression). Requires code transformation (via Babel, browserify, webpack, etc.) to generate detailed failure messages. Differentiated from chai/should by reusing the native assert module; you can swap require('power-assert') for require('assert') with zero API change. Works server-side and browser-side. Maintained by the original author but has been stable with infrequent releases.

testing

npm install power-assert

github ↗package ↗

INSTALL

IMPORT

SIG · POWER-ASSERT

power-assert

testingjavascriptv1.6.1

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.

default

✓ import 'power-assert'; const assert = require('assert');

✗ const assert = require('power-assert');

Import side-effects to augment assert module; then use native assert. This is the recommended pattern.

default

✓ const assert = require('power-assert');

✗ const assert = require('assert');

This works but less transparent; side-effect import is preferred.

assert

✓ import assert from 'power-assert';

✗ import { assert } from 'power-assert';

Named export is not available; use default import.

Usage with Babel: augment assert, then use native assert methods; power-assert provides detailed diffs.

// Install: npm install --save-dev power-assert babel-plugin-espower // .babelrc: { "plugins": ["babel-plugin-espower"] } // test.js import 'power-assert'; const assert = require('assert'); const a = [1, 2, 3]; const b = [1, 2, 3, 4]; assert.deepStrictEqual(a, b); // Without transformation: AssertionError [ERR_ASSERTION]: [1,2,3] deepStrictEqual [1,2,3,4] // With power-assert transformation: // assert.deepStrictEqual(a, b) // | | // | [1,2,3,4] // [1,2,3]

Debug

Known issues

gotchaWithout code transformation, power-assert falls back to normal assert output.

fix

Add a code transformation step (Babel plugin, browserify transform, webpack loader, etc.) to your build process.

affects: >=1.0.0

breakingIn v1.0.0, the API changed to require side-effect import (import 'power-assert') instead of requiring the module directly.

fix

Use import 'power-assert' at module top; still call require('assert') for assertions.

affects: >=1.0.0

deprecatedBower package is maintained but no longer updated; Bower itself is deprecated.

fix

Use npm to install power-assert.

affects: all

gotchapower-assert relies on AST transformation; test files must be transpiled before execution.

fix

Ensure test files are transformed via Babel, browserify, or other tools. Use babel-plugin-espower or eslint-plugin-espower as part of the build.

affects: >=1.0.0

gotchaWhen using mocha with power-assert, you must configure the test runner to perform transformation (e.g., require babel-register).

fix

Run mocha with --require babel-register and Babel config with babel-plugin-espower.

affects: >=1.0.0

Errors

Common errors & fixes

TypeError: assert(expression) is not a function

Importing power-assert incorrectly (e.g., using named import).

fix

Use `import 'power-assert'` as a side-effect import, not expecting named exports.

AssertionError [ERR_ASSERTION]: Expression is not truthy

power-assert transformation did not run; test code not transpiled.

fix

Add babel-plugin-espower to Babel config and run test with Babel.

Cannot find module 'power-assert'

power-assert not installed in node_modules.

fix

Run `npm install --save-dev power-assert`.

ReferenceError: require is not defined

Using `require('assert')` in ES module (type: module) environment.

fix

Switch to ES module import: `import assert from 'assert'` after `import 'power-assert'`.

Upgrade

Version history

1.6.1latest on npm

Audit

Dependencies

empowerrequiredredefines assert methods for power-assert output

power-assert-formatterrequiredformats assertion error messages

espowerrequiredtransform library to instrument test code

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/power-assert-js/power-assert ↗

packagehttps://www.npmjs.com/package/power-assert ↗