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https://github.com/shouldjs/should.js

BDD style assertions for node.js -- test framework agnostic
https://github.com/shouldjs/should.js

assertions bdd javascript node-js should tdd test testing tests

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BDD style assertions for node.js -- test framework agnostic

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# should.js



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_should_ is an expressive, readable, framework-agnostic assertion library. The main goals of this library are __to be expressive__ and __to be helpful__. It keeps your test code clean, and your error messages helpful.



By default (when you `require('should')`) _should_ extends the `Object.prototype` with a single non-enumerable getter that allows you to express how that object should behave. It also returns itself when required with `require`.



It is also possible to use should.js without getter (it will not even try to extend Object.prototype), just `require('should/as-function')`. Or if you already use version that auto add getter, you can call `.noConflict` function.



**Results of `(something).should` getter and `should(something)` in most situations are the same**



### Upgrading instructions



Please check [wiki page](https://github.com/shouldjs/should.js/wiki/Breaking-changes) for upgrading instructions.



### FAQ



You can take look in [FAQ](https://github.com/shouldjs/should.js/wiki/FAQ).



## Example

```javascript

var should = require('should');



var user = {

    name: 'tj'

  , pets: ['tobi', 'loki', 'jane', 'bandit']

};



user.should.have.property('name', 'tj');

user.should.have.property('pets').with.lengthOf(4);



// If the object was created with Object.create(null)

// then it doesn't inherit `Object.prototype`, so it will not have `.should` getter

// so you can do:

should(user).have.property('name', 'tj');



// also you can test in that way for null's

should(null).not.be.ok();



someAsyncTask(foo, function(err, result){

  should.not.exist(err);

  should.exist(result);

  result.bar.should.equal(foo);

});

```

## To begin



 1. Install it:



    ```bash

    $ npm install should --save-dev

    ```



 2. Require it and use:



    ```js

    var should = require('should');



    (5).should.be.exactly(5).and.be.a.Number();

    ```



    ```js

    var should = require('should/as-function');



    should(10).be.exactly(5).and.be.a.Number();

    ```



 3. For TypeScript users:

  

    ```js

    import * as should from 'should';



    (0).should.be.Number();

    ```



## In browser



Well, even when browsers by complaints of authors have 100% es5 support, it does not mean it has no bugs. Please see [wiki](https://github.com/shouldjs/should.js/wiki/Known-Bugs) for known bugs.



If you want to use _should_ in browser, use the `should.js` file in the root of this repository, or build it yourself. To build a fresh version:



```bash

$ npm install

$ npm run browser

```



The script is exported to `window.should`:



```js

should(10).be.exactly(10)

```



You can easy install it with npm or bower:



```sh

npm install should -D

# or

bower install shouldjs/should.js

```



## API docs



Actual api docs generated by jsdoc comments and available at [http://shouldjs.github.io](http://shouldjs.github.io).



## Usage examples



Please look on usage in [examples](https://github.com/shouldjs/examples)



## .not



`.not` negates the current assertion.



## .any



`.any` allow for assertions with multiple parameters to assert any of the parameters (but not all). This is similar to the native JavaScript [array.some](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some).



# Assertions

## chaining assertions



Every assertion will return a `should.js`-wrapped Object, so assertions can be chained.

To help chained assertions read more clearly, you can use the following helpers anywhere in your chain: `.an`, `.of`, `.a`, `.and`, `.be`, `.have`, `.with`, `.is`, `.which`. Use them for better readability; they do nothing at all.

For example:

```js

user.should.be.an.instanceOf(Object).and.have.property('name', 'tj');

user.pets.should.be.instanceof(Array).and.have.lengthOf(4);

```

Almost all assertions return the same object - so you can easy chain them. But some (eg: `.length` and `.property`) move the assertion object to a property value, so be careful.



## Adding own assertions



Adding own assertion is pretty easy. You need to call `should.Assertion.add` function. It accept 2 arguments:



1. name of assertion method (string)

2. assertion function (function)



What assertion function should do. It should check only positive case. `should` will handle `.not` itself.

`this` in assertion function will be instance of `should.Assertion` and you **must** define in any way this.params object

 in your assertion function call before assertion check happen.



`params` object can contain several fields:



- `operator` - it is string which describe your assertion

- `actual` it is actual value, you can assume it is your own this.obj if you need to define you own

- `expected` it is any value that expected to be matched this.obj



You can assume its usage in generating AssertionError message like: expected `obj`? || this.obj not? `operator` `expected`?



In `should` sources appeared 2 kinds of usage of this method.



First not preferred and used **only** for shortcuts to other assertions, e.g how `.should.be.true()` defined:



```javascript

Assertion.add('true', function() {

    this.is.exactly(true);

});

```

There you can see that assertion function do not define own `this.params` and instead call within the same assertion `.exactly`

that will fill `this.params`. **You should use this way very carefully, but you can use it**.



Second way preferred and i assume you will use it instead of first.



```javascript

Assertion.add('true', function() {

    this.params = { operator: 'to be true', expected: true };



    should(this.obj).be.exactly(true);

});

```

in this case this.params defined and then used new assertion context (because called `.should`). Internally this way does not

 create any edge cases as first.



```javascript

Assertion.add('asset', function() {

    this.params = { operator: 'to be asset' };



    this.obj.should.have.property('id').which.is.a.Number();

    this.obj.should.have.property('path');

})



//then

> ({ id: '10' }).should.be.an.asset();

AssertionError: expected { id: '10' } to be asset

    expected '10' to be a number



> ({ id: 10 }).should.be.an.asset();

AssertionError: expected { id: 10 } to be asset

    expected { id: 10 } to have property path

```



## Additional projects



* [`should-sinon`](https://github.com/shouldjs/sinon) - adds additional assertions for sinon.js

* [`should-immutable`](https://github.com/shouldjs/should-immutable) - extends different parts of should.js to make immutable.js first-class citizen in should.js

* [`should-http`](https://github.com/shouldjs/http) - adds small assertions for assertion on http responses for node only

* [`should-jq`](https://github.com/shouldjs/jq) - assertions for jq (need maintainer)

* [`karma-should`](https://github.com/seegno/karma-should) - make more or less easy to work karma with should.js

* [`should-spies`](https://github.com/shouldjs/spies) - small and dirty simple zero dependencies spies



## Contributions



[Actual list of contributors](https://github.com/visionmedia/should.js/graphs/contributors) if you want to show it your friends.



To run the tests for _should_ simply run:



    $ npm test



See also [CONTRIBUTING](./CONTRIBUTING.md).



## OMG IT EXTENDS OBJECT???!?!@



Yes, yes it does, with a single getter _should_, and no it won't break your code, because it does this **properly** with a non-enumerable property.



Also it is possible use it without extension. Just use `require('should/as-function')` everywhere.



## License



MIT. See LICENSE for details.