Complete training workflow and acceptance hardening

backend/tests/test_db_pool_config.py

@@ -0,0 +1,54 @@
+from types import SimpleNamespace
+
+import pytest
+from pydantic import ValidationError
+
+from app.config import Settings
+
+
+def test_database_pool_defaults_fit_two_backend_node_budget():
+    settings = Settings(_env_file=None)
+    assert settings.db_pool_size == 20
+    assert settings.db_pool_max_overflow == 10
+    # Two backend nodes use at most 60 application connections, leaving room
+    # under PostgreSQL's common 100-connection default for admin/backup work.
+    assert 2 * (settings.db_pool_size + settings.db_pool_max_overflow) == 60
+
+
+@pytest.mark.parametrize("values", [{"db_pool_size": 0}, {"db_pool_max_overflow": -1}])
+def test_database_pool_rejects_invalid_limits(values):
+    with pytest.raises(ValidationError):
+        Settings(_env_file=None, **values)
+
+
+def test_engine_uses_configured_pool_limits(monkeypatch):
+    from app.db import base
+
+    observed = {}
+    sentinel = object()
+
+    def capture(url, **options):
+        observed["url"] = url
+        observed.update(options)
+        return sentinel
+
+    settings = SimpleNamespace(
+        database_url="postgresql+asyncpg://lct:test@localhost/lct",
+        db_pool_size=12,
+        db_pool_max_overflow=7,
+    )
+    monkeypatch.setattr(base, "get_settings", lambda: settings)
+    monkeypatch.setattr(base, "create_async_engine", capture)
+    base.reset()
+    try:
+        assert base.get_engine() is sentinel
+    finally:
+        base.reset()
+
+    assert observed == {
+        "url": settings.database_url,
+        "pool_pre_ping": True,
+        "pool_size": 12,
+        "max_overflow": 7,
+        "hide_parameters": True,
+    }