Fix missing __init__.py

tests/__init__.py

@@ -0,0 +1,39 @@
+# Copyright (c) MONAI Consortium
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#     http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import sys
+import unittest
+import warnings
+
+
+def _enter_pr_4800(self):
+    """
+    code from https://github.com/python/cpython/pull/4800
+    """
+    # The __warningregistry__'s need to be in a pristine state for tests
+    # to work properly.
+    for v in list(sys.modules.values()):
+        if getattr(v, "__warningregistry__", None):
+            v.__warningregistry__ = {}
+    self.warnings_manager = warnings.catch_warnings(record=True)
+    self.warnings = self.warnings_manager.__enter__()
+    warnings.simplefilter("always", self.expected)
+    return self
+
+
+# FIXME: workaround for https://bugs.python.org/issue29620
+try:
+    # Suppression for issue #494:  tests/__init__.py:34: error: Cannot assign to a method
+    unittest.case._AssertWarnsContext.__enter__ = _enter_pr_4800  # type: ignore
+except AttributeError:
+    pass