standalone assertion libraries?

Question

I was nearly through porting YUI assertion modules to standalone libraries when the thought popped into mind that I should have perhaps asked on StackOverflow if this was necessary first. However I finished the libs:

YUIPort: https://github.com/gso/YUIPort

But thought I would duly ask as well. Are there any good quality standalone libraries of assert functions - these can be very useful, e.g., checking the validity of arguments passed to functions (can save a lot of time invoking the debugger).

Answer 1

As of May 7, 2012

After some brief research, starting with the most minimalistic:

• assert.js - port of node assert functions
• jShould - QUnit extension
• should.js - node library
• expect.js - based on should.js, standalone
• YUIPort - YUI libs but standalone
• chai - node and browser, plugins inc. for JQuery
• expectThat - CoffeeScript

I have to admit that I do tend to agree with a commenter on DailyJS:

I don't understand why everyone likes these wordy assertion libraries.

Although I'm not a CoffeeScript user, I do tend to gravitate towards the plain assert.js style syntax rather than all this chaining.

Features that these libraries are developing include:

• plugable with the major test suites (saves having to switch between two libraries when coding)
• coding server-side (node) and client-side without changing libraries
• integration into the main web frameworks (e.g. JQuery)

Some of the major test suites include:

• JQuery's QUnit
• Mocha
• Jasmine
• js-test-driver
• YUI Test
• Sinon.JS

The major web frameworks often include their own test suites.

Logging wise, there is a discussion on libraries available. They don't, at a glance, seem to have caught up with server-side JS as of yet.

Answer 2

function assert(condition, message) {     if (!condition) throw new Error(message) }