Provide proper error message if interface name is invalid

Currently if an invalid interface name is used for the
"openstack baremetal introspection interface show" command the
unhelpful message "need more than 0 values to unpack" is
returned.  This fix returns a better message.

Story: 2002749
Task: 22603
Change-Id: I0556b64e39c5b3e9be0cfecfb6d741a4e5cd16e7

ironic_inspector_client/test/test_v1.py

@@ -427,8 +427,7 @@ class TestInterfaceApi(BaseTest):
             self.uuid, "em1", fields)
         self.assertEqual(expected_values, iface_dict)
 
-        # Test interface name not in 'all_interfaces'
-        expected_values = collections.OrderedDict()
-        iface_dict = self.get_client().get_interface_data(
-            self.uuid, "em55", fields)
-        self.assertEqual(expected_values, iface_dict)
+    def test_invalid_interface(self, mock_req):
+        mock_req.return_value.json.return_value = self.inspector_db
+        self.assertRaises(ValueError, self.get_client().get_interface_data,
+                          self.uuid, "em55", ["node_ident", "interface"])

ironic_inspector_client/v1.py

@@ -287,6 +287,7 @@ class ClientV1(http.BaseClient):
         :param interface: interface name
         :param field_sel: list of all fields for which to get data
         :returns: interface data in OrderedDict
+        :raises: ValueError if interface is not found.
         """
         # Use OrderedDict to maintain order of user-entered fields
         iface_data = collections.OrderedDict()
@@ -296,7 +297,9 @@ class ClientV1(http.BaseClient):
 
         # Make sure interface name is valid
         if interface not in all_interfaces:
-            return iface_data
+            raise ValueError(
+                _("Interface %s was not found on this node")
+                % interface)
 
         # If lldp data not available this will still return interface,
         # mac, node_ident etc.

releasenotes/notes/change-error-msg-invalid-interface-4b6b70b92c27d6f6.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - The error message returned when running the
+    `openstack baremetal introspection interface show`
+    command with an interface not associated with the node has been fixed.
+    It now indicates that the interface was invalid.