Restructure omni services and add Chatwoot research snapshot

research/chatwoot/spec/services/whatsapp/token_exchange_service_spec.rb

@@ -0,0 +1,45 @@
+require 'rails_helper'
+
+describe Whatsapp::TokenExchangeService do
+  let(:code) { 'test_authorization_code' }
+  let(:service) { described_class.new(code) }
+  let(:api_client) { instance_double(Whatsapp::FacebookApiClient) }
+
+  before do
+    allow(Whatsapp::FacebookApiClient).to receive(:new).and_return(api_client)
+  end
+
+  describe '#perform' do
+    context 'when code is valid' do
+      let(:token_response) { { 'access_token' => 'new_access_token' } }
+
+      before do
+        allow(api_client).to receive(:exchange_code_for_token).with(code).and_return(token_response)
+      end
+
+      it 'returns the access token' do
+        expect(service.perform).to eq('new_access_token')
+      end
+    end
+
+    context 'when code is blank' do
+      let(:service) { described_class.new('') }
+
+      it 'raises ArgumentError' do
+        expect { service.perform }.to raise_error(ArgumentError, 'Authorization code is required')
+      end
+    end
+
+    context 'when response has no access token' do
+      let(:token_response) { { 'error' => 'Invalid code' } }
+
+      before do
+        allow(api_client).to receive(:exchange_code_for_token).with(code).and_return(token_response)
+      end
+
+      it 'raises an error' do
+        expect { service.perform }.to raise_error(/No access token in response/)
+      end
+    end
+  end
+end