test(datasource): cover SQLAlchemy pool disposal

backend/tests/test_connection_pool_manager.py

@@ -0,0 +1,103 @@
+"""Regression tests for SQLAlchemy connection pool lifecycle management."""
+
+import ast
+import os
+import threading
+from collections import OrderedDict
+from types import SimpleNamespace
+from unittest.mock import Mock
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+
+_SRC_PATH = os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
+    "apps",
+    "db",
+    "db.py",
+)
+
+
+def _load_connection_pool_manager():
+    """Load only ConnectionPoolManager to avoid importing database drivers."""
+    with open(_SRC_PATH, encoding="utf-8") as file:
+        source = file.read()
+
+    tree = ast.parse(source)
+    class_node = next(
+        node
+        for node in tree.body
+        if isinstance(node, ast.ClassDef) and node.name == "ConnectionPoolManager"
+    )
+
+    class CoreDatasource:
+        pass
+
+    class AssistantOutDsSchema:
+        pass
+
+    namespace = {
+        "threading": threading,
+        "OrderedDict": OrderedDict,
+        "CoreDatasource": CoreDatasource,
+        "AssistantOutDsSchema": AssistantOutDsSchema,
+        "sessionmaker": sessionmaker,
+        "get_engine": None,
+    }
+    module = ast.Module(body=[class_node], type_ignores=[])
+    ast.fix_missing_locations(module)
+    exec(compile(module, _SRC_PATH, "exec"), namespace)
+    return namespace["ConnectionPoolManager"], namespace
+
+
+ConnectionPoolManager, _namespace = _load_connection_pool_manager()
+
+
+def _engine_factory(created_engines):
+    def get_engine(ds, use_pool=False):
+        assert use_pool is True
+        engine = create_engine("sqlite://")
+        engine.dispose = Mock(wraps=engine.dispose)
+        created_engines.append(engine)
+        return engine
+
+    return get_engine
+
+
+def test_remove_pool_disposes_bound_engine():
+    created_engines = []
+    _namespace["get_engine"] = _engine_factory(created_engines)
+    manager = ConnectionPoolManager()
+
+    manager.get_pool(SimpleNamespace(id="ds-1"))
+    manager.remove_pool("ds-1")
+
+    created_engines[0].dispose.assert_called_once_with()
+    assert "ds-1" not in manager._pools
+
+
+def test_lru_eviction_disposes_oldest_engine():
+    created_engines = []
+    _namespace["get_engine"] = _engine_factory(created_engines)
+    manager = ConnectionPoolManager(max_pools=1)
+
+    manager.get_pool(SimpleNamespace(id="ds-1"))
+    manager.get_pool(SimpleNamespace(id="ds-2"))
+
+    created_engines[0].dispose.assert_called_once_with()
+    created_engines[1].dispose.assert_not_called()
+
+
+def test_close_all_disposes_every_engine():
+    created_engines = []
+    _namespace["get_engine"] = _engine_factory(created_engines)
+    manager = ConnectionPoolManager(max_pools=2)
+
+    manager.get_pool(SimpleNamespace(id="ds-1"))
+    manager.get_pool(SimpleNamespace(id="ds-2"))
+    manager.close_all()
+
+    for engine in created_engines:
+        engine.dispose.assert_called_once_with()
+    assert not manager._pools