Refactor Conversation model (#134)

* Add Conversation factory with dependent factories

* Include FactoryBot methods in rspec config

* Add unit tests for public methods of Conversation model

* Move Current model into a separate file in lib folder

* Disable Metrics/BlockLength rule for db/migrate and spec folders

* Get rid of global $dispatcher variable

* Create Message#unread_since scope

* Refactor callback methods in Conversation model

* Create Conversations::EventDataPresenter

* Add translation keys for activity messages

* Add pry-rails gem

* Refactor Conversation#notify_status_change

* Add mock_redis for test env

spec/presenters/conversations/event_data_presenter_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Conversations::EventDataPresenter do
+  let(:presenter) { described_class.new(conversation) }
+  let(:conversation) { create(:complete_conversation) }
+
+  describe '#lock_data' do
+    it { expect(presenter.lock_data).to eq(id: conversation.display_id, locked: false) }
+  end
+
+  describe '#push_data' do
+    let(:expected_data) do
+      {
+        meta: {
+          sender: conversation.sender.push_event_data,
+          assignee: conversation.assignee
+        },
+        id: conversation.display_id,
+        messages: [],
+        inbox_id: conversation.inbox_id,
+        status: conversation.status_before_type_cast.to_i,
+        timestamp: conversation.created_at.to_i,
+        user_last_seen_at: conversation.user_last_seen_at.to_i,
+        agent_last_seen_at: conversation.agent_last_seen_at.to_i,
+        unread_count: 0
+      }
+    end
+
+    it 'returns push event payload' do
+      expect(presenter.push_data).to eq(expected_data)
+    end
+  end
+end