alt="MagicMock.js">

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Mocked objects with ES6, inspired by python's unittest.mock module.

Install

``sh
npm i -D --save-dev magicmock
`

Prerequisite

Use magicmock with Node.js/io.js (with --harmony_proxies). Currently we only test it against Node.js 4 and Node.js 5. To request more engine support, please kindly send in an issue or pull request.

Usage

$3

The terms method and function are interchangeable here.

`
import {mockMethod} from 'magicmock';

let mockedMethod = mockMethod();
mockedMethod.returnValue = 100;
mockedMethod(1, 2, 3); // => 100
console.log(mockedMethod.called()); // => true
console.log(mockedMethod.calledWith(1, 2, 3)); // => true
console.log(mockedMethod.calledWith(1, 2)); // => false
`

##### mockedMethod.returnValue / options.returnValue

Setting returnValue property of the mockedMethod changes the return value when executing mockedMethod.

returnValue is also accepted as an option to mockMethod() factory method.

`
let mockedMethod = mockMethod({
returnValue: 100
});
mockedMethod(1, 2, 3); // => 100
`

##### options.sideEffect

options.sideEffect allows mockedMethod returns different values depending on side effects from outside world. If sideEffect was defined, returnValue won't not work anymore.

`
let method = mockMethod({
sideEffect: [1, 4, 2]
});
method(); // => 1
method(); // => 4
method(); // => 2
method(); // => undefined
`

It also accepts a mapping function.

`
let resultMap = {'a': 1, 'b': 2, 'c': 3}
let method = mockMethod({
sideEffect: (key) => resultMap[key]
});
method('a'); // => 1
method('b'); // => 2
method('c'); // => 3
method('d'); // => undefined
`

mockedMethod can raise an error defined by options.sideEffect.

`
let mockedMethod = mockMethod({
sideEffect: new Error('My GOSH!')
});
mockedMethod(); // => throws error
`

##### mockedMethod.callCount()

Returns how many times was the method called.

##### mockedMethod.called()

Returns a boolean. Indicates whether the method was called or not.

##### mockedMethod.calledWith(args)

Returns a boolean. Indicates whether the method was called with exactly the same argument list or not.

##### mockedMethod.getInvocationHistory()

Returns an array of argument lists which mockedMethod was called.

`
let method = mockMethod();
method();
method(1);
method({a: 1});
method.getInvocationHistory(); // => [[], [1], [{a: 1}]]
`

$3

mockObject() factory method creates an object mockedObject. When you access any of undefined property of mockedObject, it returns a mockedMethod instead of undefined.

`
let mockedObject = mockObject();
// mockedObject.testMethod is undefined
mockedObject.testMethod.returnValue = 101;
console.log(mockedObject.testMethod()); // => 101
`

You could still assign property value to mockedObject after its creation.

`
let mockedObject = mockObject();
// mockedObject.testMethod is undefined
mockedObject.testMethod.returnValue = 101;
console.log(mockedObject.testMethod()); // => 101
mockedObject.testMethod = 'not a method anymore';
console.log(mockedObject.testMethod()); // => 'not a method anymore'
`

mockObject() factory method accepts an option with props key, which defines properties upon creation.

`
let mockedObject = mockObject({
props: {
myProperty: 'this is a string'
}
});
console.log(mockedObject.myProperty); // => this is a string
`

Use for testing only

magicmock was designed for testing. You don't want to run magicmock code in production code, neither client-side nor server-side.

If you are using mocha to run test, simply add flag --harmony_proxies. You'd better use some ES6 transpiler like babel.

`
mocha --compilers js:babel-register --harmony_proxies
``

License

MIT © tjwudi

[npm-url]: https://npmjs.org/package/magicmock
[npm-image]: https://img.shields.io/npm/v/magicmock.svg?style=flat-square

[travis-url]: https://travis-ci.org/tjwudi/magicmock
[travis-image]: https://img.shields.io/travis/tjwudi/magicmock.svg?style=flat-square

[coveralls-url]: https://coveralls.io/r/tjwudi/magicmock
[coveralls-image]: https://img.shields.io/coveralls/tjwudi/magicmock.svg?style=flat-square

[depstat-url]: https://david-dm.org/tjwudi/magicmock
[depstat-image]: https://david-dm.org/tjwudi/magicmock.svg?style=flat-square

[download-badge]: http://img.shields.io/npm/dm/magicmock.svg?style=flat-square