feat(auth): implement auth stack

tests/db/test_get_conn.py

@@ -0,0 +1,80 @@
+"""Tests for the get_conn dependency helper."""
+
+from __future__ import annotations
+
+import pytest
+
+from app.db import db, get_conn
+
+
+pytestmark = pytest.mark.asyncio
+
+
+class _FakeConnection:
+    def __init__(self, idx: int) -> None:
+        self.idx = idx
+
+
+class _AcquireContext:
+    def __init__(self, conn: _FakeConnection, tracker: "_FakePool") -> None:
+        self._conn = conn
+        self._tracker = tracker
+
+    async def __aenter__(self) -> _FakeConnection:
+        self._tracker.active += 1
+        return self._conn
+
+    async def __aexit__(self, exc_type, exc, tb) -> None:
+        self._tracker.active -= 1
+
+
+class _FakePool:
+    def __init__(self) -> None:
+        self.acquire_calls = 0
+        self.active = 0
+
+    def acquire(self) -> _AcquireContext:
+        conn = _FakeConnection(self.acquire_calls)
+        self.acquire_calls += 1
+        return _AcquireContext(conn, self)
+
+
+async def _collect_single_connection():
+    connection = None
+    async for conn in get_conn():
+        connection = conn
+    return connection
+
+
+async def test_get_conn_reuses_connection_within_scope():
+    original_pool = db.pool
+    fake_pool = _FakePool()
+    db.pool = fake_pool
+    try:
+        captured: list[_FakeConnection] = []
+
+        async for outer in get_conn():
+            captured.append(outer)
+            async for inner in get_conn():
+                captured.append(inner)
+
+        assert len(captured) == 2
+        assert captured[0] is captured[1]
+        assert fake_pool.acquire_calls == 1
+    finally:
+        db.pool = original_pool
+
+
+async def test_get_conn_acquires_new_connection_per_root_scope():
+    original_pool = db.pool
+    fake_pool = _FakePool()
+    db.pool = fake_pool
+    try:
+        first = await _collect_single_connection()
+        second = await _collect_single_connection()
+
+        assert first is not None and second is not None
+        assert first is not second
+        assert fake_pool.acquire_calls == 2
+    finally:
+        db.pool = original_pool