avow

avow

Assertion library to allow one to throw custom errors.

avow uses ES2015 Proxies to intercept calls to assert. All methods of assert are available, and it is compatible with both Node.js's standard assertion library and the one on npm.

Motivation

To allow assert to throw custom errors.

Example

assert encapsulates Custom Errors under an AssertionError, which sucks

const assert = require('assert')
assert(false, Error('yohoo')

{ AssertionError: Error: yohoo
    at Object.<anonymous> (/tmp/a/index.js:2:1)
  name: 'AssertionError',
  actual: false,
  expected: true,
  operator: '==',
  message: 
   Error: yohoo
       at Object.<anonymous> (/tmp/a/index.js:2:15)
  generatedMessage: false }

Stack-trace trimmed for readability.

avow throws Custom Errors properly, which is nice

const avow = require('avow')
avow(false, Error('yohoo'))
Error: yohoo
    at Object.<anonymous> (/tmp/a/index.js:2:16)

Stack-trace trimmed for readability.

Installation

Make sure assert is installed.

The npm library assert is not a dependency in package.json in order to allow one to use Node.js's standard assert library.