babel-plugin-empower-assert

2.0.0 verified Sat Apr 25 auth: no javascript

Babel plugin that transforms standard Node.js assert() calls into power-assert empowered assertions at compile time, enabling detailed failure messages with expression graph visualization. Version 2.0.0 requires Babel 7 and power-assert 1.x. The package is lightweight, focused solely on the transformation step, and must be used alongside power-assert. For Babel 6, use version 1.x. Provides enhanced debugging for tests but adds no runtime overhead.

Common errors

error Error: Cannot find module 'babel-plugin-empower-assert' ↓

cause Plugin not installed or installed in wrong location (e.g., globally instead of locally)

fix

Run npm install --save-dev babel-plugin-empower-assert in your project directory.

error ReferenceError: assert is not defined ↓

cause The transformed code requires power-assert at runtime, but it is missing from dependencies

fix

Install power-assert: npm install power-assert --save

error Error: Plugin/Preset files are not allowed to export objects, only functions ↓

cause Using version 2.x with Babel 6; Babel 6 expects function-based plugins, but 2.x exports as object for Babel 7

fix

Use version 1.x for Babel 6: npm install babel-plugin-empower-assert@1.4.0 --save-dev

Warnings

breaking Babel 7 is incompatible with Babel 6. Use version 1.x for Babel 6. ↓

fix Downgrade to version 1.4.0 with npm install babel-plugin-empower-assert@1.4.0 --save-dev

gotcha You must have power-assert installed separately as a dependency; the plugin does not include it. ↓

fix Add power-assert to your dependencies: npm install power-assert --save-dev

gotcha The plugin only transforms require('assert') to require('power-assert'); it does not modify assert methods like assert.ok() beyond the replacement. ↓

fix Ensure power-assert is used in your runtime environment for the enhanced output.

deprecated Babel 6 version is on older release line (1.x); new development targets Babel 7. ↓

fix Migrate to Babel 7 and use version 2.0.0.

Install

npm install babel-plugin-empower-assert

yarn add babel-plugin-empower-assert

pnpm add babel-plugin-empower-assert

Imports

babel-plugin-empower-assert
wrong
```
"plugins": ["empower-assert"]
```
correct
```
"plugins": ["babel-plugin-empower-assert"]
```
Plugin name used in .babelrc or Babel config. Short form 'empower-assert' (without 'babel-plugin-' prefix) also works, but full name is preferred for clarity.
default
wrong
```
import empowerAssert from 'babel-plugin-empower-assert';
```
correct
```
const empowerAssert = require('babel-plugin-empower-assert');
```
The plugin is distributed as CommonJS and typically not used directly via import; it's loaded by Babel's plugin system.
assert
wrong
```
var assert = require('assert');
```
correct
```
var assert = require('power-assert');
```
After transformation, the require('assert') is rewritten to require('power-assert'). In source code, you still write require('assert'), but the plugin changes it at compile time.

Quickstart

Shows configuration (.babelrc) and source code example that will be transformed by babel-plugin-empower-assert.

// Install dependencies:
// npm install --save-dev babel-plugin-empower-assert power-assert

// .babelrc
{
  "env": {
    "development": {
      "plugins": ["babel-plugin-empower-assert"]
    }
  }
}

// source.js (before transformation)
'use strict';
var assert = require('assert');
function add(a, b) {
    assert(!isNaN(a));
    assert.equal(typeof b, 'number');
    return a + b;
}

// After babel transformation, 'require("assert")' becomes 'require("power-assert")'