fix/added tests to cover db lookup for session refresh tokens

tests/integration/test_session_schema_real.py

@@ -0,0 +1,28 @@
+"""Integration tests for the live session-table schema."""
+
+from __future__ import annotations
+
+import pytest
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import AsyncSession
+
+
+@pytest.mark.asyncio
+async def test_sessions_refresh_hash_lookup_is_backed_by_unique_index(
+    db_session: AsyncSession,
+) -> None:
+    """The migrated sessions table should expose a unique index on hashed_refresh_token."""
+    result = await db_session.execute(text("""
+            SELECT indexname, indexdef
+            FROM pg_indexes
+            WHERE schemaname = current_schema()
+              AND tablename = 'sessions'
+            """))
+
+    indexes = {str(row.indexname): str(row.indexdef).lower() for row in result.mappings().all()}
+
+    assert indexes
+    assert any(
+        "unique index" in indexdef and "hashed_refresh_token" in indexdef
+        for indexdef in indexes.values()
+    )