don't include quizzes locked by date in epub export

test plan:
* have a quiz set to be locked until a future date
* a student should not be able to see the quiz
 content in a epub export

closes #ADMIN-842

Change-Id: I323bc3df36b8078e88331a08a85abb7914c92efb
Reviewed-on: https://gerrit.instructure.com/142958
Tested-by: Jenkins
Reviewed-by: Mysti Sadler <mysti@instructure.com>
QA-Review: Deepeeca Soundarrajan <dsoundarrajan@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>

lib/cc/qti/qti_generator.rb

@@ -61,6 +61,7 @@ module CC
 
         Quizzes::ScopedToUser.new(@course, @user, @course.quizzes.active).scope.each do |quiz|
           next unless export_object?(quiz) || export_object?(quiz.assignment)
+          next if @user && !@course.grants_right?(@user, :read_as_admin) && quiz.locked_for?(@user, check_policies: true)
 
           title = if quiz
                     quiz.title

spec/lib/cc/exporter/web_zip/zip_package_spec.rb

@@ -829,6 +829,14 @@ describe "ZipPackage" do
           }]
       end
 
+      it "should not export quizzes when locked by date" do
+        quiz = @course.quizzes.create!(title: 'Quiz 1', description: "stuff",
+          workflow_state: "available", unlock_at: 3.days.from_now)
+        @module.content_tags.create!(content: quiz, context: @course, indent: 0)
+        course_data = create_zip_package.parse_course_data
+        expect(course_data[:quizzes]).to be_empty
+      end
+
       it "should export linked file items in sub-folders" do
         folder = @course.folders.create!(name: 'folder#1', parent_folder: Folder.root_folders(@course).first)
         file = add_file(fixture_file_upload('files/cn_image.jpg', 'image/jpg'), @course, "cn_image.jpg", folder)