Merge pull request #2315 from pypa/feature/417-tests

Add tests capturing expected distutils behavior.

setup.cfg

@@ -72,6 +72,7 @@ tests =
     paver; python_version>="3.6"
     futures; python_version=="2.7"
     pip>=19.1 # For proper file:// URLs support.
+    jaraco.envs
 
 docs =
     # Keep these in sync with docs/requirements.txt

setuptools/tests/requirements.txt

@@ -10,3 +10,4 @@ pytest-cov>=2.5.1
 paver; python_version>="3.6"
 futures; python_version=="2.7"
 pip>=19.1 # For proper file:// URLs support.
+jaraco.envs

setuptools/tests/test_distutils_adoption.py

+import os
+import sys
+import functools
+import subprocess
+import platform
+
+import pytest
+import jaraco.envs
+import path
+
+
+class VirtualEnv(jaraco.envs.VirtualEnv):
+    name = '.env'
+
+    def run(self, cmd, *args, **kwargs):
+        cmd = [self.exe(cmd[0])] + cmd[1:]
+        return subprocess.check_output(cmd, *args, cwd=self.root, **kwargs)
+
+
+@pytest.fixture
+def venv(tmpdir):
+    env = VirtualEnv()
+    env.root = path.Path(tmpdir)
+    env.req = os.getcwd()
+    return env.create()
+
+
+def popen_text(call):
+    """
+    Augment the Popen call with the parameters to ensure unicode text.
+    """
+    return functools.partial(call, universal_newlines=True) \
+        if sys.version_info < (3, 7) else functools.partial(call, text=True)
+
+
+def find_distutils(venv, imports='distutils', env=None, **kwargs):
+    py_cmd = 'import {imports}; print(distutils.__file__)'.format(**locals())
+    cmd = ['python', '-c', py_cmd]
+    if platform.system() == 'Windows':
+        env['SYSTEMROOT'] = os.environ['SYSTEMROOT']
+    return popen_text(venv.run)(cmd, env=env, **kwargs)
+
+
+def test_distutils_stdlib(venv):
+    """
+    Ensure stdlib distutils is used when appropriate.
+    """
+    assert venv.name not in find_distutils(venv, env=dict()).split(os.sep)
+
+
+def test_distutils_local_with_setuptools(venv):
+    """
+    Ensure local distutils is used when appropriate.
+    """
+    env = dict(SETUPTOOLS_USE_DISTUTILS='local')
+    loc = find_distutils(venv, imports='setuptools, distutils', env=env)
+    assert venv.name in loc.split(os.sep)
+
+
+@pytest.mark.xfail(reason="#2259")
+def test_distutils_local(venv):
+    env = dict(SETUPTOOLS_USE_DISTUTILS='local')
+    assert venv.name in find_distutils(venv, env=env).split(os.sep)