fn-spy

fn-spy

creating spies for your functions

api

const spy = require('fn-spy')

spy.calledCount() integer, returns the number of times a function as called

spy.calledWith() array, returns the arguments passed to the function

spy.restore() function, restores the function to the initial state

spy an emitter function

const spyMyEmitter = spy.emitter() and will return the same methods as above

spy a callback function

const spyMyEmitter = spy.callback() and will return the same methods as above

examples

generic example

const spy = require('fn-spy')

function foo (...args) {
  return args.length
}

let spiedFn = spy(foo)

// calledCount
spiedFn()
spiedFn()
spiedFn.calledCount()// will return 2

// calledWith
spiedFn(1, 2, 3)
spiedFn.calledWith()// will return [[1, 2, 3]]

// restore
spiedFn = spiedFn.restore()// now spiedFn is retored to the initial state

emitter example

const EE = require('events')
const spy = require('fn-spy')

const myEmitter = new EE()
const spyEmitter = spy.emitter()

myEmitter.on('hey', spyEmitter)

myEmitter.emit('hey')

spyEmitter.calledCount()// will return 1
spyEmitter.calledWith()// will return [[]]

callback example

const spy = require('fn-spy')

const spyCallback = spy.callback()

 function someFunction (cb) {
    cb()
  }

someFunction(spyCallback)

spyCallback.calledCount()// will return 1
spyCallback.calledWith()// will return [[]]

ISC License (ISC)