Reduce nesting depth in tests to respect server CQL limit

Scylla now limits CQL expression nesting depth to 12 (CVE-2026-31948,
scylladb commit e35c388), rejecting deeper literals with the error
"expression nested too deeply".

The limit counts every recursive `term`, including the innermost
scalar value:
- nested tuple literals max out at 11 levels deep
- nested UDT literals max out at 10 levels deep (a UDT literal
  {value: ...} adds two term levels per nesting)

Prepared statements serialize values and bypass the parser limit, so
only simple-statement/literal inserts are affected.

Adjust test_can_insert_nested_tuples to depth 11 and the nested UDT
tests to depth 10.

Author: sylwiaszunejko

tests/integration/standard/test_types.py

@@ -663,20 +663,22 @@ def test_can_insert_nested_tuples(self):
         s.encoder.mapping[tuple] = s.encoder.cql_encode_tuple
 
         # create a table with multiple sizes of nested tuples
-        # Note: Scylla limits CQL expression nesting depth to 12, so the
-        # deepest tuple tested here is 12 levels deep.
+        # Note: Scylla limits CQL expression nesting depth to 12 (every
+        # recursive `term` counts, including the innermost scalar value), so a
+        # nested tuple literal can be at most 11 levels deep before the server
+        # rejects it with "expression nested too deeply".
         s.execute("CREATE TABLE nested_tuples ("
                   "k int PRIMARY KEY, "
                   "v_1 frozen<%s>,"
                   "v_2 frozen<%s>,"
                   "v_3 frozen<%s>,"
-                  "v_12 frozen<%s>"
+                  "v_11 frozen<%s>"
                   ")" % (self.nested_tuples_schema_helper(1),
                          self.nested_tuples_schema_helper(2),
                          self.nested_tuples_schema_helper(3),
-                         self.nested_tuples_schema_helper(12)))
+                         self.nested_tuples_schema_helper(11)))
 
-        for i in (1, 2, 3, 12):
+        for i in (1, 2, 3, 11):
             # create tuple
             created_tuple = self.nested_tuples_creator_helper(i)
 

tests/integration/standard/test_udts.py

@@ -389,7 +389,12 @@ def test_can_insert_nested_registered_udts(self):
         with self._cluster_default_dict_factory() as c:
             s = c.connect(self.keyspace_name, wait_for_all_pools=True)
 
-            max_nesting_depth = 12
+            # Scylla caps CQL expression nesting depth at 12 (every recursive
+            # `term` counts). A UDT literal `{value: ...}` adds two term levels
+            # per nesting, so a UDT literal inserted via a simple statement can
+            # be at most 10 levels deep before the server rejects it with
+            # "expression nested too deeply".
+            max_nesting_depth = 10
 
             # create the schema
             self.nested_udt_schema_helper(s, max_nesting_depth)
@@ -417,7 +422,10 @@ def test_can_insert_nested_unregistered_udts(self):
         with self._cluster_default_dict_factory() as c:
             s = c.connect(self.keyspace_name, wait_for_all_pools=True)
 
-            max_nesting_depth = 12
+            # This test inserts via prepared statements (serialized values), so
+            # it is not subject to the parser's nesting limit. Keep it aligned
+            # with the literal-insert tests for consistency.
+            max_nesting_depth = 10
 
             # create the schema
             self.nested_udt_schema_helper(s, max_nesting_depth)
@@ -454,7 +462,12 @@ def test_can_insert_nested_registered_udts_with_different_namedtuples(self):
         with self._cluster_default_dict_factory() as c:
             s = c.connect(self.keyspace_name, wait_for_all_pools=True)
 
-            max_nesting_depth = 12
+            # Scylla caps CQL expression nesting depth at 12 (every recursive
+            # `term` counts). A UDT literal `{value: ...}` adds two term levels
+            # per nesting, so a UDT literal inserted via a simple statement can
+            # be at most 10 levels deep before the server rejects it with
+            # "expression nested too deeply".
+            max_nesting_depth = 10
 
             # create the schema
             self.nested_udt_schema_helper(s, max_nesting_depth)