Add stress tests

AGENTS.md

@@ -48,7 +48,9 @@
   run and destroys it at session end. Run them with
   `tox -e integration` or
   `.venv/bin/pytest tests/integration`. Throughput comparison against
-  native VDDK lives under `tests/perf/` (`tox -e perf`).
+  native VDDK lives under `tests/perf/` (`tox -e perf`). Repeated
+  connect/open/close leak checks live under `tests/stress/`
+  (`tox -e stress`).
 
 
 ## Other rules

README.md

@@ -69,6 +69,7 @@ VDDK-shaped handle.
 | `openvixdisklib/fastlz.py`         | FastLZ NFC adapter (pip `pyfastlz`)                    |
 | `tests/integration/`               | Live pytest suite against a lab vCenter                |
 | `tests/perf/`                      | Throughput comparison of openvixdisklib vs VDDK        |
+| `tests/stress/`                    | Repeated connect/open/close leak check                 |
 | `tests/integration/vixdisklib.py`  | Native VDDK wrapper used only to cross-check           |
 | `docs/`                            | Protocol notes and reverse-engineering steps           |
 
@@ -114,6 +115,14 @@ plain and FastLZ):
 tox -e perf
 ```
 
+Repeat ``connect`` / ``open`` / write-read one sector / ``close`` /
+``disconnect`` 200 times (one process, sequential, like many VMs) and
+assert the fd count does not grow:
+
+```bash
+tox -e stress
+```
+
 VDDK cross-check tests skip when `libvixDiskLib` is not loadable from
 `.vddk`. `tox -e integration` sets `LD_LIBRARY_PATH` to that directory
 and clears `LD_PRELOAD`. For a direct pytest run, do the same.

tests/stress/test_connect_open_close.py

@@ -0,0 +1,72 @@
+# Copyright 2026 Cloudbase Solutions Srl
+# All Rights Reserved.
+
+"""Repeat connect/open/close against the lab to catch leaked sockets."""
+
+from __future__ import annotations
+
+import gc
+import os
+
+import pytest
+
+from openvixdisklib import openvixdisklib as vixdisklib
+from tests.integration.base import SECTOR_SIZE, LabEnv, pattern_bytes
+
+# Sequential ConnectEx + Open, as when migrating many VMs in one process.
+_ITERATIONS = 200
+# Noise from pytest/OpenSSL; one leaked socket per iteration is 200.
+_FD_SLACK = 8
+
+
+def _fd_count() -> int:
+    """Return the number of open file descriptors in this process."""
+    return len(os.listdir("/proc/self/fd"))
+
+
+@pytest.mark.skipif(
+    not os.path.isdir("/proc/self/fd"),
+    reason="fd leak check needs /proc/self/fd",
+)
+class TestConnectOpenReadWriteClose:
+    def test_repeated_connect_open_read_write_close_does_not_leak_fds(
+        self,
+        lab: LabEnv,
+    ) -> None:
+        """Connect, open, write/read one sector, and close ``_ITERATIONS`` times.
+
+        Each cycle is a full ``VixDiskLib_ConnectEx`` / ``Open`` /
+        ``Close`` / ``Disconnect`` for the lab VM (ticket, authd, NFC).
+        After the loop the process fd count must not have grown by more
+        than ``_FD_SLACK``.
+        """
+        handle = vixdisklib.VixDiskLibHandle(
+            vixdisklib_compatibility_version="8.0", config_path=None
+        )
+        write_buf = vixdisklib.get_buffer(SECTOR_SIZE)
+        read_buf = vixdisklib.get_buffer(SECTOR_SIZE)
+        kwargs = lab.vixdisklib_connect_kwargs(
+            {
+                "allow_untrusted": lab.allow_untrusted,
+                "transport_modes": "nbdssl",
+            }
+        )
+        gc.collect()
+        fds_before = _fd_count()
+        for i in range(_ITERATIONS):
+            expected = pattern_bytes(SECTOR_SIZE, f"STRESS-{i}-".encode())
+            write_buf[:SECTOR_SIZE] = expected
+            with (
+                handle.connect(**kwargs) as conn,
+                handle.open(conn, lab.disk_path, flags=0) as disk,
+            ):
+                handle.write(disk, 0, 1, write_buf)
+                read_buf[:SECTOR_SIZE] = b"\xa5" * SECTOR_SIZE
+                handle.read(disk, 0, 1, read_buf)
+            assert read_buf.raw[:SECTOR_SIZE] == expected
+        gc.collect()
+        fds_after = _fd_count()
+        assert fds_after <= fds_before + _FD_SLACK, (
+            f"open fds grew from {fds_before} to {fds_after} after "
+            f"{_ITERATIONS} connect/open/close cycles"
+        )

tox.ini

@@ -60,6 +60,15 @@ setenv =
 commands =
     python -m pytest -v -s tests/perf/ {posargs}
 
+[testenv:stress]
+description = Repeat connect/open/close against the lab to detect socket leaks.
+sitepackages = True
+usedevelop = True
+setenv =
+    {[testenv:integration]setenv}
+commands =
+    python -m pytest -v tests/stress/ {posargs}
+
 [testenv:fmt]
 description = Format the code based on the coding style standards.
 deps =