Welcome to Unexpected

The extensible BDD assertion toolkit

expect({ text: 'f00!' }, 'to equal', { text: 'foo!' });

expected { text: 'f00!' } to equal { text: 'foo!' }

{

text:

'f00!'

should equal

'foo!'

f00!

foo!

}

Badges

Features

Extensible
Fast
Provides really nice error messages
Helps you if you misspells assertions
Compatible with all test frameworks.
Node.JS ready (require('unexpected'))
Supports asynchronous assertions using promises
Single global with no prototype extensions or shims.
Cross-browser: works on Chrome, Firefox, Safari, Opera, IE6+, (IE6-IE8 with es5-shim)

Node

Install it with NPM or add it to your package.json:

$ npm install unexpected

Then:

var expect = require('unexpected');

Browser

Include unexpected.js.

This will expose the expect function under the following namespace:

var expect = weknowhow.expect;

RequireJS

Include the library with RequireJS the following way:

require.config({

paths: {

unexpected: 'path/to/unexpected'

}

});

define(['unexpected'], function (expect) {

// Your code

});

Using Unexpected with a test framework

For example, if you create a test suite with mocha.

Let's say we wanted to test the following program:

math.js

function add (a, b) { return a + b; };

Our test file would look like this:

describe('math.js', function () {

describe('add', function () {

it('is a function', function () {

expect(add, 'to be a', 'function');

});

it('adds numbers', function () {

expect(add(1, 3), 'to be', 4);

});

If a certain expectation fails, an exception will be raised which gets captured and shown/processed by the test runner.

Source

The source for Unexpected can be found on Github.

Releases

10.0.0

Assertions are now declared with explicit type requirements for the arguments as part of the pattern. This is a breaking change that removes support for the old addAssertion syntax where the subject type(s) were passed as the first argument. See addAssertion for more information.
The to be >, to be >=, to be <, and to be <= assertions have been removed as they clashed with the new type syntax. Please use the fully spelled-out variants: to be greater than, to be less than or equal to, etc.
The [not] to begin with, [not] to end with, and [not] to contain assertions now require strings as the needle(s). Previously they supported any type, which would then be stringified.
Inside an assertion you can now access the errorMode, shift, flags, alternations properties etc. via the expect passed to the assertion. They can still be accessed via this as previously, but that is deprecated. (This change actually debuted in 9.12.0).
The when passed as parameter(s) to, when called with, when decoded as can now be used standalone, ie. without delegating the result to another assertion in the same expect call. In that case they will provide the result as the fulfillment value of the promise.

9.0.0

Build all error messages lazily. This is an internal refactoring that makes it possible to generate very different output in the text, Ansi, and HTML modes using the magicpen raw feature. This change mostly affects plugins, and we have updated all the official plugins accordingly, so please upgrade those to the latest version when you upgrade to Unexpected 9.
Made it possible to tweak the default error message when creating assertions. See addAssertion for more information.
Expanded the to have message assertion defined for Error instances to allow matching a serialization other than plain text: to have ansi message, to have html message.
The to contain assertion defined for strings: When the assertion fails, display a "diff" where partial matches are highlighted.

8.0.0

All errors originating from assertions are now instances of UnexpectedError, which can be manipulated before being serialized.
Error messages and diffs are now built lazily, improving performance.
Unexpected now detects created promises that were never returned and fails synchronously. This will uncover some extremely nasty bugs where the test suite succeeds when it should actually fail. This feature only works in Mocha and Jasmine.
Deprecated error.output, please use error.getErrorMessage() instead.
Deprecated error.label, please use error.getLabel() instead.
when decoded as, when called with, when passed as parameter to, when passed as parameters to: Require the 4th argument to be a string specifying an assertion. Previously a function was also allowed, which turned out to be error prone. This also affects all plugins that use the internal function Assertion.prototype.shift to delegate to other assertions.
Nested error mode: Don't repeat the subject when it takes up multiple lines and is identical to the parent subject.
Added a new bubbleThrough error mode that will make the error bubble all the way to the top, mainly useful internally.
Added to error assertion.
Minor bugfixes and output tweaks.

7.0.0

Support for asynchronous assertions using promises. All built-in assertions that delegate to other assertions (such as to satisfy) have been rewritten to support this. The change is fully backwards compatible.
Removed support for the to be an array of and to be an array of (strings|numbers|...) assertions. There are better and more flexible alternatives.
Renamed assertions so that the subject type isn't mentioned in the assertion name. The old names are kept around as aliases for now. These assertions are affected:
- to be an array whose items satisfy => to have items satisfying
- to be an (object|hash|map) whose keys satisfy => to have keys satisfying
- to be an (object|hash|map) whose values satisfy => to have values satisfying Also, these 3 assertions no longer pass for empty collections.
New when passed as parameter to constructor and when passed as parameter to async "adverbial" assertions.
New when decoded as "adverbial" assertion for Buffer instances.
New to have message assertion defined for Error instances.
A lot of output improvements and minor tweaks.

6.0.0

New documentation and corresponding site.
Use Object.is/the SameValue algorithm when checking equality of primitive values (the to be and to equal assertions).
Tweaked the output of numerous assertions.
Constrained to be empty and to have length to only work with strings and array-like objects.
Renamed the arrayLike type to array-like.
Changed style names and added theming support (mostly internal).
Removed grammatically incorrect assertions.

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.