Chainable, extensible assertion framework for Javascript
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README.md

Totes - Chainable, expandable assertion library for javascript

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Install

npm install totes

Usage

var expect = require('totes').expect;

expect wraps the value in an Assertable object

var assertable = expect(testExpression);

Assertable objects have several assertion functions available

assertable.isTruthy();
assertable.is(expressionToTestAgainstValue);
assertable.isExactly(expressionToTestAgainstValueAndType);

If any assertion fails, it will throw an AssertionError which will be detected by test runners including mocha

Chaining

You can chain assertions for more terse syntax

expect(testExpression)
    .isTruthy()
    .is(someOtherExpression)
    .isExactly(aThirdExpression);

Expanding

Since totes has a small core centered around the Assertable object, you can write your own assertions by extending the Assertable prototype.

var Assertable = require('totes').assertable;

Assertable.prototype.isHelloString = function(){
  // you can access the internal value with this.value
  return this.isTrue(function(val){
      return typeof(val) === 'string' &&  val === 'Hello';
  }, 'Custom assertion error goes here');
}

Then to use the new function, simply call it like any other assertion

expect('Hello').isHelloString(); // Should pass
expect('other string').isHelloString(); // Should fail

Simply return this.isTrue or this.isFalse to hook into the chaining mechanism.

NOTE: If you use totes in browser tests (for example in karma) then replace expect with totesExpect. I made this change to avoid clashing with other libraries like chai.

License

Copyright (c) 2014 Christopher Gillis

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.

Text for license retrieved from http://opensource.org/licenses/MIT