feat: add sla events table (#9126)

* feat: add sla events table

* chore: refactor to EE namespace

* chore: refactor

* chore: fix spec

* chore: add references to account,inbox,sla_policy

* chore: update specs

* chore: update spec to check backfilling id's

* Update spec/enterprise/models/sla_event_spec.rb

spec/enterprise/models/sla_event_spec.rb

@@ -0,0 +1,28 @@
+require 'rails_helper'
+
+RSpec.describe SlaEvent, type: :model do
+  describe 'associations' do
+    it { is_expected.to belong_to(:applied_sla) }
+    it { is_expected.to belong_to(:conversation) }
+    it { is_expected.to belong_to(:account) }
+    it { is_expected.to belong_to(:sla_policy) }
+    it { is_expected.to belong_to(:inbox) }
+  end
+
+  describe 'validates_factory' do
+    it 'creates valid sla event object' do
+      sla_event = create(:sla_event)
+      expect(sla_event.event_type).to eq 'frt'
+    end
+  end
+
+  describe 'backfilling ids' do
+    it 'automatically backfills account_id, inbox_id, and sla_id upon creation' do
+      sla_event = create(:sla_event)
+
+      expect(sla_event.account_id).to eq sla_event.conversation.account_id
+      expect(sla_event.inbox_id).to eq sla_event.conversation.inbox_id
+      expect(sla_event.sla_policy_id).to eq sla_event.applied_sla.sla_policy_id
+    end
+  end
+end