feat: Introduce compatibility with native namespace packages (#187)

* feat: Introduce compatibility with native namespace packages

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: parthea

packages/google-cloud-access-context-manager/google/__init__.py

@@ -45,10 +45,6 @@
     package for package in setuptools.find_packages() if package.startswith("google")
 ]
 
-# Determine which namespaces are needed.
-namespaces = ["google"]
-namespaces.append("google.identity")
-
 setuptools.setup(
     name=name,
     version=version,
@@ -75,7 +71,6 @@
     ],
     platforms="Posix; MacOS X; Windows",
     packages=packages,
-    namespace_packages=namespaces,
     install_requires=dependencies,
     python_requires=">=3.7",
     include_package_data=True,

packages/google-cloud-access-context-manager/google/identity/__init__.py

@@ -0,0 +1,48 @@
+# Copyright 2023 Google LLC
+#
+# 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.
+
+import os
+import subprocess
+import sys
+
+
+def test_namespace_package_compat(tmp_path):
+    # The ``google`` namespace package should not be masked
+    # by the presence of ``google-cloud-access-context-manager``.
+    google = tmp_path / "google"
+    google.mkdir()
+    google.joinpath("othermod.py").write_text("")
+    env = dict(os.environ, PYTHONPATH=str(tmp_path))
+    cmd = [sys.executable, "-m", "google.othermod"]
+    subprocess.check_call(cmd, env=env)
+
+    # The ``google.identity`` namespace package should not be masked
+    # by the presence of ``google-cloud-access-context-manager``.
+    google_identity = tmp_path / "google" / "identity"
+    google_identity.mkdir()
+    google_identity.joinpath("othermod.py").write_text("")
+    env = dict(os.environ, PYTHONPATH=str(tmp_path))
+    cmd = [sys.executable, "-m", "google.identity.othermod"]
+    subprocess.check_call(cmd, env=env)
+
+    # The ``google.identity.accesscontextmanager`` namespace package should not be masked
+    # by the presence of ``google-cloud-access-context-manager``.
+    google_identity_accesscontextmanager = (
+        tmp_path / "google" / "identity" / "accesscontextmanager"
+    )
+    google_identity_accesscontextmanager.mkdir()
+    google_identity_accesscontextmanager.joinpath("othermod.py").write_text("")
+    env = dict(os.environ, PYTHONPATH=str(tmp_path))
+    cmd = [sys.executable, "-m", "google.identity.accesscontextmanager.othermod"]
+    subprocess.check_call(cmd, env=env)