feat: Add the support for custom attributes in message variables (#8511)

spec/drops/contact_drop_spec.rb

@@ -3,7 +3,7 @@ require 'rails_helper'
 describe ContactDrop do
   subject(:contact_drop) { described_class.new(contact) }
 
-  let!(:contact) { create(:contact) }
+  let!(:contact) { create(:contact, custom_attributes: { car_model: 'Tesla Model S', car_year: '2022' }) }
 
   context 'when first name' do
     it 'returns first name' do
@@ -38,4 +38,19 @@ describe ContactDrop do
       expect(subject.last_name).to eq 'Doe'
     end
   end
+
+  context 'when accessing custom attributes' do
+    it 'returns the correct car model from custom attributes' do
+      expect(contact_drop.custom_attribute['car_model']).to eq 'Tesla Model S'
+    end
+
+    it 'returns the correct car year from custom attributes' do
+      expect(contact_drop.custom_attribute['car_year']).to eq '2022'
+    end
+
+    it 'returns empty hash when there are no custom attributes' do
+      contact.update!(custom_attributes: nil)
+      expect(contact_drop.custom_attribute).to eq({})
+    end
+  end
 end