added mvi service handling for 200 from vaafi but 500 from mvi

lib/mvi/service.rb

@@ -67,6 +67,7 @@ def call(operation, body)
         Rails.logger.error response.body
         raise MVI::HTTPError.new('MVI HTTP call failed', response.status)
       end
+      raise MVI::HTTPError.new('MVI internal server error', 500) if body_has_error(response.body)
       response
     end
 
@@ -79,6 +80,17 @@ def request_failure_handler(operation, xml)
       Rails.logger.error "mvi #{operation} request failure: #{xml}"
       raise MVI::RequestFailureError
     end
+
+    def body_has_error(body)
+      doc = Ox.parse(body)
+      fault_element = doc.locate('env:Envelope/env:Body/env:Fault').first
+      return false unless fault_element
+      fault_code = fault_element.locate('faultcode').first
+      fault_string = fault_element.locate('faultstring').first
+      Rails.logger.error "MVI fault code: #{fault_code.nodes.first}" if fault_code
+      Rails.logger.error "MVI fault string: #{fault_string.nodes.first}" if fault_string
+      true
+    end
   end
   class ServiceError < StandardError
   end

spec/lib/mvi/service_spec.rb

@@ -122,6 +122,16 @@
         end
       end
     end
+
+    context 'when MVI returns 500 but VAAFI sends 200' do
+      it 'raises an MVI::HTTPError' do
+        VCR.use_cassette('mvi/find_candidate/internal_server_error') do
+          expect(Rails.logger).to receive(:error).with('MVI fault code: env:Server').once
+          expect(Rails.logger).to receive(:error).with('MVI fault string: Internal Error (from server)').once
+          expect { subject.find_candidate(message) }.to raise_error(MVI::HTTPError, 'MVI internal server error')
+        end
+      end
+    end
   end
 
   describe MVI::RecordNotFound do