Setup basic Revision History page

Sets up paper_trail tracking in important models

and add conference_id to versions for storing conference_id
of conference related objects  as metadata.This will help in querying
for versions related to conferences.

Fix issues with factories & event types initialization.Import paper_trail testing helpers
Fix bug: Creating an event creates a useless version with event update

Add revert and view changes features to revision history

spec/controllers/admin/versions_controller_spec.rb

@@ -0,0 +1,101 @@
+require 'spec_helper'
+
+describe Admin::VersionsController do
+
+  let!(:conference) { create(:conference, short_title: 'exampletitle', description: 'Example Description') }
+  let(:admin) { create(:admin) }
+
+  with_versioning do
+    describe 'GET #revert' do
+      before :each do
+        sign_in admin
+      end
+
+      it 'reverts all changes for update actions' do
+        conference.update_attributes(short_title: 'testtitle', description: 'Some random text')
+        get :revert_object, id: PaperTrail::Version.last.id
+        conference.reload
+        expect(conference.short_title).to eq 'exampletitle'
+        expect(conference.description).to eq 'Example Description'
+      end
+
+      it 'shows correct flash on trying to revert create event of a deleted object' do
+        creation_version_id = conference.program.event_types.first.versions.first.id
+        conference.program.event_types.first.destroy
+        get :revert_object, id: creation_version_id
+        expect(flash[:error]).to match('The item is already in the state that you are trying to revert it back to')
+      end
+
+      it 'reverting deletion of object  creates it again' do
+        conference.program.event_types.first.destroy
+        event_types_count = conference.program.event_types.count
+        get :revert_object, id: PaperTrail::Version.last.id
+        conference.reload
+        expect(PaperTrail::Version.last.event).to eq 'create'
+        expect(conference.program.event_types.count).to eq(event_types_count + 1)
+      end
+
+      it 'reverting creation of object deletes it ' do
+        create(:lodging, conference: conference)
+        get :revert_object, id: PaperTrail::Version.last.id
+        expect(PaperTrail::Version.last.event).to eq 'destroy'
+        expect(Lodging.count).to eq 0
+      end
+
+      it 'reverting creation of conference is not permitted' do
+        conference_count_before = Conference.count
+        get :revert_object, id: conference.versions.first.id
+        expect(flash[:alert]).to eq 'You are not authorized to access this page.'
+        expect(Conference.count).to eq(conference_count_before)
+      end
+    end
+
+    describe 'GET #revert_attribute' do
+      before :each do
+        sign_in admin
+      end
+
+      it 'reverts specified change for update actions' do
+        conference.update_attributes(short_title: 'testtitle', description: 'Some random text')
+        get :revert_attribute, id: PaperTrail::Version.last.id, attribute: 'short_title'
+        conference.reload
+        expect(conference.short_title).to eq 'exampletitle'
+        expect(conference.description).to eq 'Some random text'
+      end
+
+      it 'shows correct flash on trying to revert to the current state' do
+        conference.update_attributes(short_title: 'testtitle', description: 'Some random text')
+        conference.update_attributes(short_title: 'exampletitle')
+        get :revert_attribute, id: PaperTrail::Version.all[-2].id, attribute: 'short_title'
+        expect(flash[:error]).to match('The item is already in the state that you are trying to revert it back to')
+        expect(conference.short_title).to eq 'exampletitle'
+      end
+
+      it 'fails on trying to revert deleted object' do
+        conference.program.event_types.first.update_attributes(title: 'New Event Title')
+        conference.program.event_types.first.destroy
+        get :revert_attribute, id: PaperTrail::Version.all[-2].id, attribute: 'title'
+        conference.reload
+        expect(flash[:alert]).to eq 'You are not authorized to access this page.'
+      end
+
+      it 'fails on trying to revert creation event' do
+        create(:lodging, conference: conference)
+        get :revert_attribute, id: PaperTrail::Version.last.id, attribute: 'name'
+        expect(flash[:alert]).to eq 'You are not authorized to access this page.'
+      end
+
+      it 'revert fails when attribute is invalid' do
+        conference.update_attributes(short_title: 'testtitle', description: 'Some random text')
+        before_conference_title = conference.title
+        # Note: even though title is a valid attribute of conference, it was not updated in the change we are trying to revert
+        get :revert_attribute, id: PaperTrail::Version.last.id, attribute: 'title'
+        conference.reload
+        expect(conference.short_title).to eq 'testtitle'
+        expect(conference.description).to eq 'Some random text'
+        expect(conference.title).to eq(before_conference_title)
+        expect(flash[:error]).to match('Revert failed. Attribute missing or invalid')
+      end
+    end
+  end
+end