test: update packaging test to inspect installed metadata

The CI unit test environments do not keep setuptools installed at
runtime, even though the package is installed before tests run. Inspect
the installed google-cloud-audit-log metadata instead of executing
setup.py and monkeypatching setuptools.setup.

Author: namefreezers

packages/google-cloud-audit-log/tests/unit/test_packaging.py

@@ -15,6 +15,7 @@
 import os
 import subprocess
 import sys
+from importlib import metadata
 
 
 # See https://docs.pytest.org/en/stable/how-to/tmp_path.html#the-tmp-path-fixture
@@ -39,24 +40,13 @@ def test_namespace_package_compat(tmp_path):
     subprocess.check_call(cmd, env=env)
 
 
-def test_setup_py_does_not_discover_docs_package(monkeypatch):
-    import pathlib
-    import runpy
-
-    captured_kwargs = {}
-
-    def fake_setup(**kwargs):
-        captured_kwargs.update(kwargs)
-
-    package_root = pathlib.Path(__file__).parents[2]
-    monkeypatch.chdir(package_root)
-    monkeypatch.setattr("setuptools.setup", fake_setup)
-
-    runpy.run_path(str(package_root / "setup.py"), run_name="__main__")
+def test_top_level_package_metadata_excludes_docs():
+    top_level = metadata.distribution("google-cloud-audit-log").read_text(
+        "top_level.txt"
+    )
 
-    packages = captured_kwargs["packages"]
+    assert top_level is not None
+    top_level_packages = set(top_level.splitlines())
 
-    assert "google.cloud.audit" in packages
-    assert not any(
-        package == "docs" or package.startswith("docs.") for package in packages
-    )
+    assert "google" in top_level_packages
+    assert "docs" not in top_level_packages