e2e: add DPS leak checks

tests/e2e/provisioning_e2e/conftest.py

@@ -0,0 +1,29 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for
+# license information.
+
+import pytest
+
+import dev_utils.leak_tracker as leak_tracker_module
+
+
+@pytest.hookimpl(wrapper=True)
+def pytest_runtest_call():
+    """
+    Check that DPS client objects are released after each registration test.
+
+    Successful registration shuts down the provisioning pipeline before returning. The leak check
+    runs after the test frame is released so test-local clients and results do not cause false
+    positives.
+    """
+    # DPS clients are created after this baseline, so allowing a "replacement" object would hide
+    # a real leak rather than suppress a false positive.
+    tracker = leak_tracker_module.LeakTracker()
+    tracker.track_module("azure.iot.device")
+    tracker.track_module("paho")
+    tracker.set_initial_object_list()
+
+    result = yield
+
+    tracker.check_for_leaks()
+    return result