Clean Assert
A simple, intuitive, extensible, and open-core TDD assertion library.
- Very simple assertion-style syntax with intuitive names for each method.
- About 100 built-in assertions, all fitting a few very simple patterns.
- Custom assertions are simple functions that call
assert.assertand friends. No, really. - Optimized assertions and matching algorithms keep assertions fast.
- Very extensively tested - almost 4000 tests at the time of writing.
- Tested in both Node LTS, modern browsers, and even PhantomJS 2!
So what isn't there to love?
Note: If you're concerned about the very minimal Git/version history, this library is actively maintained, and I personally use this with all new production projects I control; it's just very stable and what you might consider mostly done. Probably one of those 0.00001% of projects that are generally bug-free.
Installation
Install via npm or Yarn:
npm install --save-dev clean-assert
yarn add clean-assert
Or, if you just want to try it out in a browser, add one of these <script> elements to your <head>:
<!-- For the latest and greatest --> <!-- For version 3 --> <!-- If you prefer to use a local copy -->Note that if you use Rollup, this is exposed as a CommonJS module, not an ES module.
API
See here. There's not a lot in terms of examples, but the API docs are self-explanatory enough usage is pretty obvious.
Motivation
This was originally designed for Thallium when I first started working on that library, because I wanted something simple, yet intuitive, and something that didn't get in my way of testing crap. I apparently did a good enough job from the gate after decoupling it from that framework that I soon found it replacing Chai for me in all new code I wrote.
I also experienced a few other issues with other libraries:
- An over-abundance of overly specific assertions like
assert.isTrue(value)orassert.lengthOf(value, 1), which add literally nothing at best to the user experience. In this, there's noassert.isTrue(value),assert.lengthOf(value, 1)or other similarly niche methods. You just useassert.equal(value, true)orassert.hasIn(value, "length", 1), respectively. - An unnecessary reliance on identity for equality. If you read
assert.equal({foo: 1}, {foo: 1}), you'd expect that to generally work if you're not thinking about strict equality semantics. In this, structural matching and value equality is the default, soassert.equal({foo: 1}, {foo: 1})works exactly how you'd expect it would. - Plugins are extremely messy, complex, and suffer from name conflicts. In this, there's no such thing as a "plugin". Custom assertions just call
assert.assert,assert.fail, orassert.failFormatonce they're ready to test (in the first case) or fail (in the second). - Most assertion libraries use a language that doesn't read like English, but instead some horribly bastardized, broken English-like pseudo-language that's trying to be somehow declarative when it's not. In this, it's all based on proper English and using imperative language - how you say it is almost always how the method is named. For a couple concrete examples:
- This library's equivalent to Chai's
assert.notDeepOwnInclude(object, "key")isassert.deeplyHasOwn(object, "key"). - This library's equivalent to Chai's
assert.oneOf(value, list)isassert.equalsAny(actual, [...expected])
- This library's equivalent to Chai's
Contributing
Found a bug? Want a feature? Report it here! Want to contribute? Keep reading.
ESLint with my preset is used to lint, and Mocha is used to run the tests. Most of the source code is in index.js and lib/, and the tests are all in test/. There's various scripts and utilities in scripts/.
The implementation is generally composed of a combination of DSLs to avoid a large amount of repetition, since most of the assertions fit the mold of "type check, test something, then throw an error if it failed".
License
Copyright (c) 2018 and later, Isiah Meadows me@isiahmeadows.com.
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.