fix google doc submissions with submissions folder enabled

test plan:
 - enable the Google Drive plugin
   (see instructions in the wiki article "OtherServiceTestAccounts",
    section "Google (Beta)")
 - enable the submissions folder feature
 - ensure that you can submit an assignment that accepts file
   uploads via the Google Doc tab

fixes CNVS-29307

Change-Id: I5bb953abd89bfcd1a8c0845eb76b1dcb78f4ef89
Reviewed-on: https://gerrit.instructure.com/79379
Tested-by: Jenkins
Reviewed-by: Steven Burnett <sburnett@instructure.com>
QA-Review: Deepeeca Soundarrajan <dsoundarrajan@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>

app/controllers/submissions_controller.rb

@@ -240,7 +240,9 @@ class SubmissionsController < ApplicationController
     end
 
     params[:submission][:attachments] = params[:submission][:attachments].compact.uniq
-    copy_attachments_to_submissions_folder! if @context.root_account.feature_enabled?(:submissions_folder)
+    if @context.root_account.feature_enabled?(:submissions_folder)
+      params[:submission][:attachments] = self.class.copy_attachments_to_submissions_folder(@context, params[:submission][:attachments])
+    end
 
     begin
       @submission = @assignment.submit_homework(@current_user, params[:submission])
@@ -299,12 +301,14 @@ class SubmissionsController < ApplicationController
   end
   private :lookup_existing_attachments
 
-  def copy_attachments_to_submissions_folder!
-    params[:submission][:attachments].map! do |attachment|
-      if attachment.folder.for_submissions?
+  def self.copy_attachments_to_submissions_folder(assignment_context, attachments)
+    attachments.map do |attachment|
+      if attachment.folder && attachment.folder.for_submissions?
         attachment # already in a submissions folder
+      elsif attachment.context.respond_to?(:submissions_folder)
+        attachment.copy_to_folder!(attachment.context.submissions_folder(assignment_context))
       else
-        attachment.copy_to_folder!(attachment.context.submissions_folder(@context))
+        attachment # in a weird context; leave it alone
       end
     end
   end

spec/controllers/submissions_controller_spec.rb

@@ -620,4 +620,41 @@ describe SubmissionsController do
     end
 
   end
+
+  describe "copy_attachments_to_submissions_folder" do
+    before(:once) do
+      course_with_student
+      attachment_model(context: @student)
+    end
+
+    it "copies a user attachment into the user's submissions folder" do
+      atts = SubmissionsController.copy_attachments_to_submissions_folder(@course, [@attachment])
+      expect(atts.length).to eq 1
+      expect(atts[0]).not_to eq @attachment
+      expect(atts[0].folder).to eq @student.submissions_folder(@course)
+    end
+
+    it "leaves files already in submissions folders alone" do
+      @attachment.folder = @student.submissions_folder(@course)
+      @attachment.save!
+      atts = SubmissionsController.copy_attachments_to_submissions_folder(@course, [@attachment])
+      expect(atts).to eq [@attachment]
+    end
+
+    it "copies a group attachment into the group submission folder" do
+      group_model(context: @course)
+      attachment_model(context: @group)
+      atts = SubmissionsController.copy_attachments_to_submissions_folder(@course, [@attachment])
+      expect(atts.length).to eq 1
+      expect(atts[0]).not_to eq @attachment
+      expect(atts[0].folder).to eq @group.submissions_folder
+    end
+
+    it "leaves files in non user/group context alone" do
+      assignment_model(context: @course)
+      weird_file = @assignment.attachments.create! name: 'blah', uploaded_data: default_uploaded_data
+      atts = SubmissionsController.copy_attachments_to_submissions_folder(@course, [weird_file])
+      expect(atts).to eq [weird_file]
+    end
+  end
 end