fix(attachments): fixes + specs for download on-receive option

spec/stores/file-download-store-spec.coffee

@@ -3,6 +3,7 @@ path = require 'path'
 {shell} = require 'electron'
 NylasAPI = require '../../src/flux/nylas-api'
 File = require '../../src/flux/models/file'
+Message = require '../../src/flux/models/message'
 FileDownloadStore = require '../../src/flux/stores/file-download-store'
 AccountStore = require '../../src/flux/stores/account-store'
 
@@ -112,6 +113,23 @@ describe "FileDownloadStore", ->
         FileDownloadStore._checkForDownloadedFile(f).then (downloaded) ->
           expect(downloaded).toBe(false)
 
+  describe "_newMailReceived", ->
+    it "should fetch attachments if the setting is on-receive", ->
+      spyOn(FileDownloadStore, '_fetch')
+      spyOn(NylasEnv.config, 'get').andCallFake (key) ->
+        return 'on-receive' if key is 'core.attachments.downloadPolicy'
+        return null
+      FileDownloadStore._newMailReceived(message: [new Message(files: [new File()])])
+      expect(FileDownloadStore._fetch).toHaveBeenCalled()
+
+    it "should not fetch attachments otherwise", ->
+      spyOn(FileDownloadStore, '_fetch')
+      spyOn(NylasEnv.config, 'get').andCallFake (key) ->
+        return 'on-read' if key is 'core.attachments.downloadPolicy'
+        return null
+      FileDownloadStore._newMailReceived(message: [new Message(files: [new File()])])
+      expect(FileDownloadStore._fetch).not.toHaveBeenCalled()
+
   describe "_runDownload", ->
     beforeEach ->
       spyOn(FileDownloadStore.Download.prototype, 'run').andCallFake -> Promise.resolve(@)

src/flux/stores/file-download-store.coffee

@@ -140,11 +140,11 @@ FileDownloadStore = Reflux.createStore
 
   ########### PRIVATE ####################################################
 
-  _newMailReceived: (incoming) =>
-    return unless NylasEnv.config.get('core.attachments.downloadPolicy') is 'on-receive'
-    for message in incoming
-      for file in message.files
-        @_fetch(file)
+  _newMailReceived: (incoming) ->
+    if NylasEnv.config.get('core.attachments.downloadPolicy') is 'on-receive'
+      for message in incoming['message']
+        for file in message.files
+          @_fetch(file)
 
   # Returns a promise with a Download object, allowing other actions to be
   # daisy-chained to the end of the download operation.

src/flux/stores/message-store.coffee

@@ -259,7 +259,9 @@ class MessageStore extends NylasStore
     startedAFetch
 
   _fetchExpandedAttachments: (items) ->
-    return unless NylasEnv.config.get('core.attachments.downloadPolicy') is 'on-read'
+    policy = NylasEnv.config.get('core.attachments.downloadPolicy')
+    return if policy is 'manually'
+
     for item in items
       continue unless @_itemsExpanded[item.id]
       for file in item.files