node-class-mock #

Allows you to mock Class methods for use in testing with a few extra testy bits thrown in.

Example ##

This will replace the method on our TestClass prototype to a method which firstly checks
the arguments passed to it and will assert.fail in the event of errors. It will then return
a resolved Promise with the given output.

`` javascript

// First, instantiate ClassMock with the class you would like to mock
const classMock = new ClassMock( TestClass );

// Then replace one of the methods
const methodMock = classMock.mock( 'myMethod' )
.shouldHaveArguments([
{ type: 'string', value: 'Hello, World!' },
{ value: 1 },
{ type: 'string', value: 'Sausages', optional: true }
])
.resolves( 'Such Promise resolution!' )

// Then anything which calls your mocked-method will
// have it's inputs checked and receieve a resolved promise
// ( other outcomes are available )
const myTestClass = new TestClass();
myTestClass.doStuff( 'Hello, World!', 1 ).then(
out => console.log( 'Hey, my test works!' )
);

// Finally, remember to un-mock!
methodMock.unMock();

``

To start-a-mocking, simply instantiate a ClassMock with your desired class ( non instantiated ). The ClassMock object exposes the following methods...

ClassMock ##

This can be considered the mock factory or the mock father or the mock-mack-daddy. Having instantiated it with your desired class, it
will produce little method mock children.

- mock

Main entry for overriding methods

Arguments

- methodName [Stirng] - Name of class method to override
- callback [Function, Optional] - Function to use as mock
- context [Object, Optional] - An instantiated object which acts as this in your override method

Returns

- methodMock [Object] - A representation of the mock dynamic

- unMock

Reinstates original method

Arguments

- methodName [String] - Name of method to reinstate

- unMockAll

Reinstate all mocked methods

Method Mocking ##

When calling mock on the mock-father you will receive back an object which exposes these methods...

- shouldHaveArguments

Provide a list of expected arguments, assert.fail if any are amiss

Arguments

- argumentDescriptorList [Array|Object] - A list of objects describing each expected parameter

- value - The expected value
- type - The typeof the argument
- optional - Some arguments are optional

- resolves

The overriden method will result in a resolved Promise being returned with the given value.

Arguments

- output - Value to resolve

- rejects

The overriden method will result in a rejected Promise being returned with the given error.

Arguments

- error - Value to reject

- returns

The overriden method will result in the specified value being returned.

Arguments

- output - Value to reject

- throws

The overriden method will result in the given error being thrown

Arguments

- error - Value to throw

- unMock

Reinstate the original function

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npm install
npm test

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babel src/class-mock.js -o lib/class-mock.js

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