Rely on pytest-home for the alternate home directory.

[jaraco]

Summary of changes

Closes

Pull Request Checklist

• Changes have tests
• News fragment added in newsfragments/.
  (See documentation for details)

[jaraco]

I also tried applying the change to test_easy_install with:

diff --git a/setuptools/tests/test_easy_install.py b/setuptools/tests/test_easy_install.py
index d71e0158..b8a066b8 100644
--- a/setuptools/tests/test_easy_install.py
+++ b/setuptools/tests/test_easy_install.py
@@ -1394,7 +1394,9 @@ def test_use_correct_python_version_string(tmpdir, tmpdir_cwd, monkeypatch):
     assert cmd.config_vars['py_version_nodot'] == '310'
 
 
-def test_editable_user_and_build_isolation(setup_context, monkeypatch, tmp_path):
+def test_editable_user_and_build_isolation(
+    setup_context, monkeypatch, tmp_path, alt_home
+):
     '''`setup.py develop` should honor `--user` even under build isolation'''
 
     # == Arrange ==
@@ -1420,9 +1422,7 @@ def test_editable_user_and_build_isolation(setup_context, monkeypatch, tmp_path)
     #
     # 2. We are going to force `site` to update site.USER_BASE and site.USER_SITE
     #    To point inside our new home
-    monkeypatch.setenv('HOME', str(tmp_path / '.home'))
-    monkeypatch.setenv('USERPROFILE', str(tmp_path / '.home'))
-    monkeypatch.setenv('APPDATA', str(tmp_path / '.home'))
+    monkeypatch.setenv('APPDATA', str(alt_home))
     monkeypatch.setattr('site.USER_BASE', None)
     monkeypatch.setattr('site.USER_SITE', None)
     user_site = Path(site.getusersitepackages())

But when I did, the tests fail with a Sandbox violation. It seems the existing test is relying on the fact that the setup script is in $temp and that the home dir is a subdir of $temp, but if that expectation isn't true, the test fails. It may be worth investigating that strange expectation, but I'm not planning to do that.