Extract shared Python test utilities into tests/helpers.py

Deduplicates exec(), vec0_shadow_table_contents(), _f32(), _i64(), and
_int8() helpers that were copied across six test files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test-metadata.py

@@ -2,6 +2,7 @@ import pytest
 import sqlite3
 from collections import OrderedDict
 import json
+from helpers import exec, vec0_shadow_table_contents
 
 
 def test_constructor_limit(db, snapshot):
@@ -594,36 +595,3 @@ def authorizer_deny_on(operation, x1, x2=None):
     return _auth
 
 
-def exec(db, sql, parameters=[]):
-    try:
-        rows = db.execute(sql, parameters).fetchall()
-    except (sqlite3.OperationalError, sqlite3.DatabaseError) as e:
-        return {
-            "error": e.__class__.__name__,
-            "message": str(e),
-        }
-    a = []
-    for row in rows:
-        o = OrderedDict()
-        for k in row.keys():
-            o[k] = row[k]
-        a.append(o)
-    result = OrderedDict()
-    result["sql"] = sql
-    result["rows"] = a
-    return result
-
-
-def vec0_shadow_table_contents(db, v):
-    shadow_tables = [
-        row[0]
-        for row in db.execute(
-            "select name from sqlite_master where name like ? order by 1", [f"{v}_%"]
-        ).fetchall()
-    ]
-    o = {}
-    for shadow_table in shadow_tables:
-        if shadow_table.endswith("_info"):
-            continue
-        o[shadow_table] = exec(db, f"select * from {shadow_table}")
-    return o