synctos/lib/simple-mock/index.js

The Syncmaker. A tool to build comprehensive sync functions for Couchbase Sync Gateway.

/* global define */
(function (global, module) { // Browser compatibility
  var simple = module.exports
  var mocks = []
  var totalCalls = 0

  /**
   * Restore the current simple and create a new one
   *
   * @param {Object} [obj]
   * @param {String} [key]
   * @api public
   */
  simple.restore = function (obj, key) {
    if (obj && key) {
      mocks.some(function (mock, i) {
        if (mock.obj !== obj || mock.key !== key) return

        mock.restore()
        mocks.splice(i, 1)
        return true
      })
      return
    }

    mocks.forEach(_restoreMock)
    mocks = []
  }

  /**
   * Create a mocked value on an object
   *
   * @param {Object} obj
   * @param {String} key
   * @param {Function|Value} mockValue
   * @return {Function} mock
   * @api public
   */
  simple.mock = function (obj, key, mockValue) {
    if (!arguments.length) {
      return simple.spyOrStub()
    } else if (arguments.length === 1) {
      return simple.spyOrStub(obj)
    } else if (isFunction(mockValue)) {
      mockValue = simple.spyOrStub(mockValue)
    } else if (arguments.length === 2) {
      mockValue = simple.spyOrStub(obj, key)
    }

    var mock = {
      obj: obj,
      key: key,
      mockValue: mockValue,
      oldValue: obj[key],
      oldValueHasKey: (key in obj)
    }

    mock.restore = _restoreMock.bind(null, mock)
    mocks.unshift(mock)

    obj[key] = mockValue
    return mockValue
  }

  /**
   * Create a stub function
   *
   * @param {Function|Object} wrappedFn
   * @param {String} [key]
   * @return {Function} spy
   * @api public
   */
  simple.spyOrStub = simple.stub = simple.spy = function (wrappedFn, key) {
    if (arguments.length === 2) {
      wrappedFn = wrappedFn[key]
    }

    var originalFn = wrappedFn

    var stubFn = function () {
      var action = (newFn.loop) ? newFn.actions[(newFn.callCount - 1) % newFn.actions.length] : newFn.actions.shift()

      if (!action) return
      if (action.throwError) throw action.throwError
      if ('returnValue' in action) return action.returnValue
      if ('fn' in action) return action.fn.apply(action.ctx || this, arguments)

      var cb = ('cbArgIndex' in action) ? arguments[action.cbArgIndex] : arguments[arguments.length - 1]
      if (action.cbArgs) return cb.apply(action.ctx || null, action.cbArgs)
    }

    var newFn = function () {
      var call = {
        k: totalCalls++, // Keep count of calls to record the absolute order of calls
        args: Array.prototype.slice.call(arguments, 0),
        arg: arguments[0],
        context: this
      }
      newFn.calls.push(call)
      newFn.firstCall = newFn.firstCall || call
      newFn.lastCall = call
      newFn.callCount++
      newFn.called = true

      try {
        call.returned = (wrappedFn || _noop).apply(this, arguments)
      } catch(e) {
        call.threw = e
        throw e
      }
      return call.returned
    }

    // Spy
    newFn.reset = function () {
      newFn.calls = []
      newFn.lastCall = { args: [] } // For dot-safety
      newFn.callCount = 0
      newFn.called = false
    }
    newFn.reset()

    // Stub
    newFn.actions = []
    newFn.loop = true

    newFn.callbackWith = newFn.callback = function () {
      wrappedFn = stubFn
      newFn.actions.push({ cbArgs: arguments })
      return newFn // Chainable
    }

    newFn.callbackArgWith = newFn.callbackAtIndex = function () {
      wrappedFn = stubFn
      newFn.actions.push({
        cbArgs: Array.prototype.slice.call(arguments, 1),
        cbArgIndex: arguments[0]
      })
      return newFn // Chainable
    }

    newFn.inThisContext = function (obj) {
      var action = newFn.actions[newFn.actions.length - 1]
      action.ctx = obj
      return newFn // Chainable
    }

    newFn.withArgs = function () {
      var action = newFn.actions[newFn.actions.length - 1]
      action.cbArgs = arguments
      return newFn // Chainable
    }

    newFn.returnWith = function (returnValue) {
      wrappedFn = stubFn
      newFn.actions.push({ returnValue: returnValue })
      return newFn // Chainable
    }

    newFn.throwWith = function (err) {
      wrappedFn = stubFn
      newFn.actions.push({ throwError: err })
      return newFn // Chainable
    }

    newFn.resolveWith = function (value) {
      if (simple.Promise.when) return newFn.callFn(function createResolvedPromise () { return simple.Promise.when(value) })
      return newFn.callFn(function createResolvedPromise () { return simple.Promise.resolve(value) })
    }

    newFn.rejectWith = function (value) {
      return newFn.callFn(function createRejectedPromise () { return simple.Promise.reject(value) })
    }

    newFn.callFn = function (fn) {
      wrappedFn = stubFn
      newFn.actions.push({ fn: fn })
      return newFn // Chainable
    }

    newFn.withActions = function (actions) {
      wrappedFn = stubFn
      if (actions && actions.length >= 0) {
        Array.prototype.push.apply(newFn.actions, actions)
      }
      return newFn // Chainable
    }

    newFn.callOriginal = newFn.callOriginalFn = function () {
      wrappedFn = stubFn
      newFn.actions.push({ fn: originalFn })
      return newFn // Chainable
    }

    newFn.withLoop = function () {
      newFn.loop = true
      return newFn // Chainable
    }

    newFn.noLoop = function () {
      newFn.loop = false
      return newFn // Chainable
    }
    return newFn
  }

  function _restoreMock (mock) {
    if (!mock.oldValueHasKey) {
      delete mock.obj[mock.key]
      return
    }
    mock.obj[mock.key] = mock.oldValue
  }

  function _noop () {}

  /**
   * Return whether the passed variable is a function
   *
   * @param {Mixed} value
   * @return {Boolean}
   * @api private
   */
  function isFunction (value) {
    return Object.prototype.toString.call(value) === funcClass
  }
  var funcClass = '[object Function]'

  // Browser compatibility
  if (typeof define === 'function' && define.amd) {
    define(function () {
      return simple
    })
  } else if (typeof window !== 'undefined') {
    window.simple = simple
  }

  // Native Promise support
  if (typeof Promise !== 'undefined') simple.Promise = Promise
})(this, typeof module !== 'undefined' ? module : {exports: {}})