Support update flags in summary message (#571)

`Summary.counters.contains_updates` and `.contains_system_updates` will use the
values provided by the server if present. Else, the driver falls back to the
previous behavior (computing the values).
This change will also make the driver ignore unknown counter names in the
summary message's 'stats' field.

Author: robsdedude

neo4j/work/summary.py

@@ -129,24 +129,52 @@ class SummaryCounters:
     #:
     system_updates = 0
 
+    _contains_updates = None
+    _contains_system_updates = None
+
     def __init__(self, statistics):
+        key_to_attr_name = {
+            "nodes-created": "nodes_created",
+            "nodes-deleted": "nodes_deleted",
+            "relationships-created": "relationships_created",
+            "relationships-deleted": "relationships_deleted",
+            "properties-set": "properties_set",
+            "labels-added": "labels_added",
+            "labels-removed": "labels_removed",
+            "indexes-added": "indexes_added",
+            "indexes-removed": "indexes_removed",
+            "constraints-added": "constraints_added",
+            "constraints-removed": "constraints_removed",
+            "system-updates": "system_updates",
+            "contains-updates": "_contains_updates",
+            "contains-system-updates": "_contains_system_updates",
+        }
         for key, value in dict(statistics).items():
-            key = key.replace("-", "_")
-            setattr(self, key, value)
+            attr_name = key_to_attr_name.get(key)
+            if attr_name:
+                setattr(self, attr_name, value)
 
     def __repr__(self):
         return repr(vars(self))
 
     @property
     def contains_updates(self):
-        """True if any of the counters except for system_updates, are greater than 0. Otherwise False."""
-        return bool(self.nodes_created or self.nodes_deleted or
-                    self.relationships_created or self.relationships_deleted or
-                    self.properties_set or self.labels_added or self.labels_removed or
-                    self.indexes_added or self.indexes_removed or
-                    self.constraints_added or self.constraints_removed)
+        """True if any of the counters except for system_updates, are greater
+        than 0. Otherwise False."""
+        if self._contains_updates is not None:
+            return self._contains_updates
+        return bool(
+            self.nodes_created or self.nodes_deleted
+            or self.relationships_created or self.relationships_deleted
+            or self.properties_set or self.labels_added
+            or self.labels_removed or self.indexes_added
+            or self.indexes_removed or self.constraints_added
+            or self.constraints_removed
+        )
 
     @property
     def contains_system_updates(self):
         """True if the system database was updated, otherwise False."""
+        if self._contains_system_updates is not None:
+            return self._contains_system_updates
         return self.system_updates > 0