[test] Test the case of XSD generation using intermediary type

e.g. for union of date and dateTime types.

test/test_profile_generation.py

@@ -401,6 +401,16 @@ class SEDAXSDExportFuncTC(XmlTestMixin, CubicWebTC):
                                 '//xs:element[@name="Keyword"]'
                                 '//xs:attribute[@name="id" and @use="optional"]')
         self.assertEqual(len(references), 1)
+        # ensure custodial item content type is properly serialized
+        chi = self.xpath(profile, '//xs:element[@name="CustodialHistoryItem"]')
+        self.assertEqual(len(chi), 1)
+        self.assertXSDAttributes(
+            chi[0],
+            [{'name': 'when', 'use': 'optional', 'type': 'datedateTime'}])
+        ddt = self.xpath(profile, '//xs:simpleType[@name="datedateTime"]')
+        self.assertEqual(len(ddt), 1)
+        self.assertEqual(ddt[0][0].tag, '{http://www.w3.org/2001/XMLSchema}union')
+        self.assertEqual(ddt[0][0].attrib, {'memberTypes': 'xsd:date xsd:dateTime'})
 
 
 if __name__ == '__main__':