Registry / testing / babel-plugin-espower

babel-plugin-espower

library3.0.1jsnpmunverified

Babel plugin for power-assert that transforms assertion expressions (assert, assert.ok, assert.equal, etc.) at build time to produce detailed, tree-structured failure messages. Current stable version is 3.0.1 (for Babel 7+). Release cadence is low, driven by power-assert ecosystem updates. Key differentiator: unlike generic assertion libraries, it leverages Babel AST rewriting to embed variable values and expression results into assertion output, enabling richer debugging without runtime instrumentation. Compatible only with Babel 7; separate major versions exist for Babel 6 (2.x) and Babel 5 (1.x).

testing

npm install babel-plugin-espower

github ↗package ↗

INSTALL

IMPORT

SIG · BABEL-PLUGIN-ESPOW

babel-plugin-espower

testingjavascriptv3.0.1

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 espower from 'babel-plugin-espower'

✗ const espower = require('babel-plugin-espower')

Package exports a single function; ESM import is recommended for Babel 7 projects. CJS require works in Node.js but may not be compatible with Babel's plugin resolution across bundlers.

Plugin

✓ plugins: ['babel-plugin-espower']

✗ plugins: [require('babel-plugin-espower')]

In .babelrc or babel.config.js, use the string name. The actual import is rarely needed; Babel resolves strings to the module internally.

Default (Babel API)

✓ babel.transform(code, { plugins: ['babel-plugin-espower'] })

✗ babel.transform(code, { plugins: [espower] })

When using Babel API, the plugin can be specified as a string. The imported function is only needed for advanced usage like custom options (none documented).

Shows a complete example of configuring babel-plugin-espower with Babel 7 and running a mocha test with power-assert.

// Install: npm install --save-dev @babel/core @babel/preset-env babel-plugin-espower power-assert mocha // Create babel.config.js: module.exports = { presets: [['@babel/preset-env', { targets: { node: 'current' } }]], plugins: ['babel-plugin-espower'] }; // test.js import assert from 'power-assert'; const alice = { name: 'alice' }; const bob = { name: 'bob' }; assert(`${alice.name} and ${bob.name}` === `bob and alice`); // Run: npx mocha --require @babel/register test.js

Debug

Known issues

breakingbabel-plugin-espower v3 is incompatible with Babel 6. You must use v2 for Babel 6 and v1 for Babel 5.

fix

Use babel-plugin-espower@2 for Babel 6, babel-plugin-espower@1 for Babel 5, or upgrade to Babel 7.

affects: >=3.0.0

breakingbabel-plugin-espower must be applied after all other syntax transforms (e.g., after preset-env) to work correctly.

fix

Place 'babel-plugin-espower' last in the plugins array in your Babel config.

affects: >=1.0.0

gotchapower-assert must be imported in test files for babel-plugin-espower to have effect; the plugin transforms calls to assert, assert.ok, etc.

fix

Ensure you have `import assert from 'power-assert'` (or `const assert = require('power-assert')`) in every test file using assert.

affects: >=1.0.0

deprecatedbabel-plugin-espower v2 is deprecated for Babel 6 users; actively maintain for Babel 7 only.

fix

Upgrade to Babel 7 and use babel-plugin-espower v3.

affects: 2.x

Errors

Common errors & fixes

Error: Cannot find module 'babel-plugin-espower'

babel-plugin-espower is not installed or version mismatched with Babel.

fix

Run `npm install --save-dev babel-plugin-espower`. Ensure Babel version matches: Babel 7 uses v3, Babel 6 uses v2, Babel 5 uses v1.

AssertionError: expected [...] to deeply equal [...] (no power-assert output)

babel-plugin-espower is not applied to the test file, or power-assert import is missing.

fix

Add 'babel-plugin-espower' to your Babel plugins configuration (after presets) and ensure test files import power-assert.

Error: Plugin or preset file "babel-plugin-espower" is not a function.

Using a version of babel-plugin-espower incompatible with your Babel version (e.g., v3 with Babel 6).

fix

Check Babel version: Babel 7 -> babel-plugin-espower@3, Babel 6 -> @2, Babel 5 -> @1.

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

babel-plugin-espower running before syntax transforms, causing AST nodes to not be fully parsed.

fix

Ensure babel-plugin-espower is listed last in the plugins array, after all presets and other plugins.

Upgrade

Version history

3.0.1latest on npm

Audit

Dependencies

@babel/corerequiredPeer dependency for Babel plugin API (Babel 7). Must be installed alongside.

Agent activity

18 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/power-assert-js/babel-plugin-espower ↗

packagehttps://www.npmjs.com/package/babel-plugin-espower ↗