Merge pull request #3046 from abravalheri/add-tests-for-duplicated-im…

…ports

Correct for duplicated distutils imports

_distutils_hack/__init__.py

@@ -57,6 +57,7 @@ def ensure_local_distutils():
     # check that submodules load as expected
     core = importlib.import_module('distutils.core')
     assert '_distutils' in core.__file__, core.__file__
+    assert 'setuptools._distutils.log' not in sys.modules
 
 
 def do_override():
@@ -112,6 +113,7 @@ def spec_for_distutils(self):
         class DistutilsLoader(importlib.abc.Loader):
 
             def create_module(self, spec):
+                mod.__name__ = 'distutils'
                 return mod
 
             def exec_module(self, module):

changelog.d/3035.misc.rst

@@ -0,0 +1 @@
+When loading distutils from the vendored copy, rewrite ``__name__`` to ensure consistent importing from inside and out.

setuptools/tests/test_distutils_adoption.py

@@ -93,3 +93,66 @@ def test_distutils_has_origin():
     Distutils module spec should have an origin. #2990.
     """
     assert __import__('distutils').__spec__.origin
+
+
+ENSURE_IMPORTS_ARE_NOT_DUPLICATED = r"""
+# Depending on the importlib machinery and _distutils_hack, some imports are
+# duplicated resulting in different module objects being loaded, which prevents
+# patches as shown in #3042.
+# This script provides a way of verifying if this duplication is happening.
+
+from distutils import cmd
+import distutils.command.sdist as sdist
+
+# import last to prevent caching
+from distutils import {imported_module}
+
+for mod in (cmd, sdist):
+    assert mod.{imported_module} == {imported_module}, (
+        f"\n{{mod.dir_util}}\n!=\n{{{imported_module}}}"
+    )
+
+print("success")
+"""
+
+
+@pytest.mark.parametrize(
+    "distutils_version, imported_module",
+    [
+        ("stdlib", "dir_util"),
+        ("stdlib", "file_util"),
+        ("stdlib", "archive_util"),
+        ("local", "dir_util"),
+        ("local", "file_util"),
+        ("local", "archive_util"),
+    ]
+)
+def test_modules_are_not_duplicated_on_import(
+        distutils_version, imported_module, tmpdir_cwd, venv
+):
+    env = dict(SETUPTOOLS_USE_DISTUTILS=distutils_version)
+    script = ENSURE_IMPORTS_ARE_NOT_DUPLICATED.format(imported_module=imported_module)
+    cmd = ['python', '-c', script]
+    output = popen_text(venv.run)(cmd, env=win_sr(env)).strip()
+    assert output == "success"
+
+
+ENSURE_LOG_IMPORT_IS_NOT_DUPLICATED = r"""
+# Similar to ENSURE_IMPORTS_ARE_NOT_DUPLICATED
+import distutils.dist as dist
+from distutils import log
+
+assert dist.log == log, (
+    f"\n{dist.log}\n!=\n{log}"
+)
+
+print("success")
+"""
+
+
+@pytest.mark.parametrize("distutils_version", "local stdlib".split())
+def test_log_module_is_not_duplicated_on_import(distutils_version, tmpdir_cwd, venv):
+    env = dict(SETUPTOOLS_USE_DISTUTILS=distutils_version)
+    cmd = ['python', '-c', ENSURE_LOG_IMPORT_IS_NOT_DUPLICATED]
+    output = popen_text(venv.run)(cmd, env=win_sr(env)).strip()
+    assert output == "success"