Allow for multiple onReadyStateChange calls (#1195)

* Closes #1150 
* Closes #2374 

* Allow for multiple onReadyStateChange calls by implementing new recursive prevention

packages/driver/src/cypress/server.coffee

@@ -359,17 +359,20 @@ create = (options = {}) ->
 
         xhr = @
         fns = {}
-        called = {}
         overrides = {}
-        readyStates = {}
 
-        onLoadFn = ->
-          ## bail if we've already been called to prevent
-          ## infinite recursion
-          return if called.onload
+        bailIfRecursive = (fn) ->
+          isCalled = false
 
-          called.onload = true
+          return () ->
+            return if isCalled
+            isCalled = true
+            try
+              return fn.apply(arguments)
+            finally
+              isCalled = false
 
+        onLoadFn = ->
           proxy._setDuration(timeStart)
           proxy._setStatus()
           proxy._setResponseHeaders()
@@ -391,12 +394,6 @@ create = (options = {}) ->
             options.onAnyResponse(route, proxy)
 
         onErrorFn = ->
-          ## bail if we've already been called to prevent
-          ## infinite recursion
-          return if called.onerror
-
-          called.onerror = true
-
           ## its possible our real onerror handler
           ## throws so we need to catch those errors too
           try
@@ -407,12 +404,6 @@ create = (options = {}) ->
             options.onError(proxy, err)
 
         onReadyStateFn = ->
-          ## bail if we've already been called with this
-          ## readyState to prevent infinite recursions
-          return if readyStates[@readyState]
-
-          readyStates[@readyState] = true
-
           ## catch synchronous errors caused
           ## by the onreadystatechange function
           try
@@ -423,9 +414,11 @@ create = (options = {}) ->
             xhr.onreadystatechange = null
             options.onError(proxy, err)
 
-        overrides.onload             = onLoadFn
-        overrides.onerror            = onErrorFn
-        overrides.onreadystatechange = onReadyStateFn
+        ## bail if eventhandlers have already been called to prevent
+        ## infinite recursion
+        overrides.onload             = bailIfRecursive(onLoadFn)
+        overrides.onerror            = bailIfRecursive(onErrorFn)
+        overrides.onreadystatechange = bailIfRecursive(onReadyStateFn)
 
         props.forEach (prop) ->
           ## if we currently have one of these properties then

packages/driver/test/cypress/integration/commands/task_spec.coffee

@@ -161,7 +161,7 @@ describe "src/cy/commands/task", ->
           expect(lastLog.get("error")).to.eq(err)
           expect(lastLog.get("state")).to.eq("failed")
 
-          expect(err.message).to.eq("cy.task('bar') failed with the following error:\n\nThe task 'bar' was not handled in the plugins file. The following tasks are registered: return:arg, wait\n\nFix this in your plugins file here:\n#{Cypress.config('pluginsFile')}\n\nhttps://on.cypress.io/api/task")
+          expect(err.message).to.eq("cy.task('bar') failed with the following error:\n\nThe task 'bar' was not handled in the plugins file. The following tasks are registered: return:arg, wait, create:long:file\n\nFix this in your plugins file here:\n#{Cypress.config('pluginsFile')}\n\nhttps://on.cypress.io/api/task")
           done()
 
         cy.task("bar")

packages/driver/test/cypress/integration/commands/xhr_spec.coffee

@@ -69,6 +69,27 @@ describe "src/cy/commands/xhr", ->
           expect(onreadystatechanged).to.be.true
           expect(xhr.status).to.eq(404)
 
+    it "allows multiple readystatechange calls", ->
+      responseText = null
+      responseStatuses = 0
+
+      cy
+        .server()
+        .route({ url: /longtext.txt/ }).as("getLongText")
+        .task('create:long:file')
+        .window().then (win) ->
+          xhr = new win.XMLHttpRequest()
+          xhr.onreadystatechange = ->
+            responseText = xhr.responseText
+            if xhr.readyState == 3
+              responseStatuses++
+          xhr.open("GET", "/_test-output/longtext.txt?" + Cypress._.random(0, 1e6))
+          xhr.send()
+          null
+        .wait("@getLongText").then (xhr) ->
+          expect(responseStatuses).to.be.gt(1)
+          expect(xhr.status).to.eq(200)
+
     it "works with jquery too", ->
       failed = false
       onloaded = false

packages/driver/test/cypress/plugins/index.js

@@ -1,3 +1,6 @@
+const _ = require('lodash')
+const path = require('path')
+const fs = require('fs-extra')
 const Promise = require('bluebird')
 
 module.exports = (on) => {
@@ -8,5 +11,14 @@ module.exports = (on) => {
     'wait' () {
       return Promise.delay(2000)
     },
+    'create:long:file' () {
+      const filePath = path.join(__dirname, '..', '_test-output', 'longtext.txt')
+      const longText = _.times(2000).map(() => {
+        return _.times(20).map(() => Math.random()).join(' ')
+      }).join('\n\n')
+
+      fs.outputFileSync(filePath, longText)
+      return null
+    },
   })
 }