Set the registry FQDN for the smt server optional

Add a test to ensure that behavior

lib/cloudregister/smt.py

@@ -39,8 +39,11 @@ def __init__(self, smtXMLNode, https_only=False):
             self._region = smtXMLNode.attrib['region']
         except KeyError:
             self._region = 'unknown'
+        try:
+            self._registry_fqdn = smtXMLNode.attrib['SMTregistryName']
+        except KeyError:
+            self._registry_fqdn = ''
         self._fqdn = smtXMLNode.attrib['SMTserverName']
-        self._registry_fqdn = smtXMLNode.attrib['SMTregistryName']
         self._fingerprint = smtXMLNode.attrib['fingerprint']
         self._cert = None
         self._cert_names = ('smt.crt', 'rmt.crt')

tests/test_registerutils.py

@@ -649,6 +649,40 @@ def test_add_hosts_entry(mock_has_rmt_ipv6_access):
     ]
 
 
+@patch('cloudregister.registerutils.has_rmt_ipv6_access')
+def test_add_hosts_entry_no_registry(mock_has_rmt_ipv6_access):
+    """Test hosts entry has a new entry added by us."""
+    smt_data_ipv46 = dedent('''\
+        <smtInfo fingerprint="00:11:22:33"
+         SMTserverIP="192.168.1.1"
+         SMTserverIPv6="fc00::1"
+         SMTserverName="fantasy.example.com"
+         region="antarctica-1"/>''')
+
+    smt_server = SMT(etree.fromstring(smt_data_ipv46))
+    mock_has_rmt_ipv6_access.return_value = True
+    with patch('builtins.open', create=True) as mock_open:
+        mock_open.return_value = MagicMock(spec=io.IOBase)
+        file_handle = mock_open.return_value.__enter__.return_value
+        utils.add_hosts_entry(smt_server)
+    mock_open.assert_called_once_with('/etc/hosts', 'a')
+    file_content_comment = (
+        '\n# Added by SMT registration do not remove, '
+        'retain comment as well\n'
+    )
+    file_content_entry = (
+        '{ip}\t{fqdn}\t{name}\n'.format(
+            ip=smt_server.get_ipv6(),
+            fqdn=smt_server.get_FQDN(),
+            name=smt_server.get_name(),
+        )
+    )
+    assert file_handle.write.mock_calls == [
+        call(file_content_comment),
+        call(file_content_entry)
+    ]
+
+
 @patch('cloudregister.registerutils.has_rmt_ipv6_access')
 def test_add_hosts_entry_registry_optional_empty(mock_has_ipv6_access):
     """Test hosts entry has a new entry added by us."""