Add EPP response code rspec matcher

#355

spec/support/matchers/epp/code.rb

@@ -0,0 +1,35 @@
+module Matchers
+  module EPP
+    class Code
+      def initialize(expected)
+        @expected = expected
+      end
+
+      def matches?(response)
+        @xml = response.body
+        actual == expected
+      end
+
+      def failure_message
+        "Expected EPP code of #{expected}, got #{actual} (#{description})"
+      end
+
+      private
+
+      attr_reader :xml
+      attr_reader :expected
+
+      def actual
+        xml_document.xpath('//xmlns:result').first['code'].to_i
+      end
+
+      def description
+        xml_document.css('result msg').text
+      end
+
+      def xml_document
+        @xml_document ||= Nokogiri::XML(xml)
+      end
+    end
+  end
+end