added test_multi_sessions

tests/test_session.py

@@ -1,4 +1,7 @@
+import asyncio
+
 import pytest
+from sqlalchemy import text
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine
 from starlette.middleware.base import BaseHTTPMiddleware
@@ -148,3 +151,24 @@ async def test_db_context_session_args(app, db, SQLAlchemyMiddleware, commit_on_
     session_args = {"expire_on_commit": False}
     async with db(session_args=session_args):
         db.session
+
+
+@pytest.mark.asyncio
+async def test_multi_sessions(app, db, SQLAlchemyMiddleware):
+    app.add_middleware(SQLAlchemyMiddleware, db_url=db_url)
+
+    async with db(multi_sessions=True):
+        async def execute_query(query):
+            return await db.session.execute(text(query))
+
+        tasks = [
+            asyncio.create_task(execute_query("SELECT 1")),
+            asyncio.create_task(execute_query("SELECT 2")),
+            asyncio.create_task(execute_query("SELECT 3")),
+            asyncio.create_task(execute_query("SELECT 4")),
+            asyncio.create_task(execute_query("SELECT 5")),
+            asyncio.create_task(execute_query("SELECT 6")),
+        ]
+
+        res = await asyncio.gather(*tasks)
+        assert len(res) == 6