callTimes

callTimes.js

function CalledMoreThanExpected(meta = {}) {
  this.name = 'CalledMoreThanExpected'
  this.message = 'Function called more than the expected times'
  this.meta = meta
  this.stack = (new Error()).stack
}
CalledMoreThanExpected.prototype = Error.prototype
CalledMoreThanExpected.prototype.constructor = CalledMoreThanExpected


function CalledWithNoFunction(meta = {}) {
  this.name = 'CalledWithNoFunction'
  this.message = 'callTimes called with argument thats not a function'
  this.meta = meta
  this.stack = (new Error()).stack
}
CalledWithNoFunction.prototype = Error.prototype
CalledWithNoFunction.prototype.constructor = CalledWithNoFunction



const callTimes = function (fn, times= 1) {
  const self = this
  const onceDate = new Date()

  if (typeof(fn) !== 'function') {
    throw new CalledMoreThanExpected({ fn, date: onceDate })
  }

  const onceCallerFunctionBody = fn.toString()
  const onceCallerFunctionName = fn.name || '__annonymous__'

  // l = l.child({ onceCallerFunctionBody, onceCallerFunctionName })

  const f = function (...args) {
    f._calledTimes += 1
    const now = new Date()
    const calledTimes = f._calledTimes
    const callInfo = { date: now, args, calledTimes }

    f._callHistory = Object.assign(callInfo, { previousCall: f._callHistory })

    const context = {
      allowedTimes: times,
      onceInfo: {
        callerFunctionBody: onceCallerFunctionBody,
        callerFunctionName: onceCallerFunctionName,
        date: onceDate,
      },
      callHistory: f._callHistory,
    }

    if (f._calledTimes > times) {
      throw new CalledMoreThanExpected(context)
    }
    console.info('Calling function', context)

    const result = fn.apply(self, args)
    context.callHistory.result = result
    return result
  }
  f._callHistory = {}
  f._calledTimes = 0
  return f
}

module.exports = callTimes

test.js

import callTimes from './callTimes'

const pow2 = (n) => n * n

const c = callTimes(pow2)
const c1 = callTimes(pow2, 1)
const c2 = callTimes(pow2, 2)

console.assert(c(2) === 4) // OK
console.assert(c(2) === 4) // Error

console.assert(c1(2) === 4) // OK
console.assert(c1(2) === 4) // Error

console.assert(c2(2) === 4) // OK
console.assert(c2(2) === 4) // OK
console.assert(c2(2) === 4) // Error