Add delete test

Author: lgarber-akamai

test/unit/objects/linode_interface_test.py

@@ -240,3 +240,10 @@ def test_update_vlan(self):
                     "ipam_address": "10.0.0.2/24",
                 },
             }
+
+    def test_delete(self):
+        iface = LinodeInterface(self.client, 123, 124)
+
+        with self.mock_delete() as m:
+            iface.delete()
+            assert m.called