Extract general functionality from get_single

sru/almasru.py

@@ -77,14 +77,27 @@ class RecordRetriever:
         :raises SruDiagnostics: if SRU returns an error
         """
 
+        sru_url = self._create_url(alma_query)
+
+        response = request.urlopen(sru_url).read()
+        sru_xml = fromstring(response)
+
+        self._raise_errors_single_records(sru_xml)
+
+        xml_list = self._extract_marc_xml(sru_xml, namespaces)
+        return xml_list[0]
+
+    def _create_url(self, alma_query: str) -> str:
+
         self.url_query['startRecord'] = '0'
         self.url_query['maximumRecords'] = '1'
         self.url_query['query'] = alma_query
         url_query_string = parse.urlencode(self.url_query)
         sru_url = self.url_base + url_query_string
 
-        response = request.urlopen(sru_url).read()
-        sru_xml = fromstring(response)
+        return sru_url
+
+    def _raise_errors_single_records(self, sru_xml: Element):
 
         namespaces = {
             'srw': 'http://www.loc.gov/zing/srw/',
@@ -112,9 +125,9 @@ class RecordRetriever:
             sru_message = sru_xml.find(xpath, namespaces).text
             raise SruDiagnostics(sru_message)
 
-        else:
+    def _extract_marc_xml(self, sru_xml, namespaces):
         record_xpath = 'srw:records/srw:record//marc:record'
-            marc_xml = sru_xml.find(record_xpath, namespaces)
+        marc_xml = sru_xml.findall(record_xpath, namespaces)
         return marc_xml
 
     def by_marc_009(self, marc_009: str) -> Element: