fixup: _RowView validation, efficient values/items, fix None-replication crash

Author: mykaul

cassandra/metadata.py

@@ -61,6 +61,11 @@ class _RowView(Mapping):
     __slots__ = ("_row", "_index_map")
 
     def __init__(self, row, index_map):
+        if len(row) < max(index_map.values(), default=-1) + 1:
+            raise ValueError(
+                "row length (%d) is insufficient for index_map with max index %d"
+                % (len(row), max(index_map.values(), default=-1))
+            )
         self._row = row
         self._index_map = index_map
 
@@ -73,6 +78,12 @@ def __iter__(self):
     def __len__(self):
         return len(self._index_map)
 
+    def values(self):
+        return (self._row[i] for i in self._index_map.values())
+
+    def items(self):
+        return ((k, self._row[i]) for k, i in self._index_map.items())
+
     def get(self, key, default=None):
         idx = self._index_map.get(key)
         if idx is not None:
@@ -3121,7 +3132,7 @@ def _build_keyspace_metadata_internal(row):
         # Read without mutating the row, since _RowView is read-only
         name = row["keyspace_name"]
         durable_writes = row.get("durable_writes", None)
-        replication = dict(row.get("replication")) if 'replication' in row else {}
+        replication = dict(row.get("replication")) if row.get("replication") else {}
         replication_class = replication.pop("class") if 'class' in replication else None
         return KeyspaceMetadata(name, durable_writes, replication_class, replication)
 
@@ -3189,7 +3200,7 @@ def get_table(self, keyspaces, keyspace, table):
     def _build_keyspace_metadata_internal(row):
         name = row["keyspace_name"]
         durable_writes = row.get("durable_writes", None)
-        replication = dict(row.get("replication")) if 'replication' in row else {}
+        replication = dict(row.get("replication")) if row.get("replication") else {}
         replication_class = replication.pop("class") if 'class' in replication else None
         graph_engine = row.get("graph_engine", None)
         return KeyspaceMetadata(name, durable_writes, replication_class, replication, graph_engine)

tests/unit/test_metadata.py

@@ -910,3 +910,31 @@ def test_row_factory_values(self):
         self.assertEqual(rows[0]["name"], "alice")
         self.assertEqual(rows[1]["id"], 2)
         self.assertEqual(rows[1]["name"], "bob")
+
+    def test_len(self):
+        rv = _RowView(("a", "b", "c"), {"x": 0, "y": 1, "z": 2})
+        self.assertEqual(len(rv), 3)
+        rv2 = _RowView((), {})
+        self.assertEqual(len(rv2), 0)
+
+    def test_keys(self):
+        rv = _RowView(("a", "b"), {"x": 0, "y": 1})
+        self.assertEqual(set(rv.keys()), {"x", "y"})
+
+    def test_values(self):
+        rv = _RowView(("a", "b"), {"x": 0, "y": 1})
+        self.assertEqual(list(rv.values()), ["a", "b"])
+
+    def test_items(self):
+        rv = _RowView(("a", "b"), {"x": 0, "y": 1})
+        self.assertEqual(set(rv.items()), {("x", "a"), ("y", "b")})
+
+    def test_init_raises_on_short_row(self):
+        with self.assertRaises(ValueError):
+            _RowView(("val",), {"a": 0, "b": 1})
+
+    def test_init_accepts_exact_row(self):
+        _RowView(("a", "b"), {"a": 0, "b": 1})
+
+    def test_init_accepts_empty(self):
+        _RowView((), {})