test: cover session start/exit in cleanup test

Author: Epochex

tests/client/test_resource_cleanup.py

@@ -50,9 +50,10 @@ async def mock_send(*args: Any, **kwargs: Any):
     initial_stream_count = len(session._response_streams)
 
     # Run the test with the patched method
-    with patch.object(session._write_stream, "send", mock_send):
-        with pytest.raises(RuntimeError):
-            await session.send_request(request, EmptyResult)
+    async with session:
+        with patch.object(session._write_stream, "send", mock_send):
+            with pytest.raises(RuntimeError, match="Simulated network error"):
+                await session.send_request(request, EmptyResult)
 
     # Verify that no response streams were leaked
     assert len(session._response_streams) == initial_stream_count, (