Make `test_pip_upgrade_from_source` xdist-friendly

setuptools/tests/fixtures.py

+import pathlib
+import shutil
+
 import pytest
 
 from . import contexts
 
 
+SRC_DIR = pathlib.Path(__file__).parents[2]
+
+
 @pytest.fixture
 def user_override(monkeypatch):
     """
@@ -21,3 +27,25 @@ def user_override(monkeypatch):
 def tmpdir_cwd(tmpdir):
     with tmpdir.as_cwd() as orig:
         yield orig
+
+
+@pytest.fixture
+def src_dir():
+    """The project source directory available via fixture."""
+    return SRC_DIR
+
+
+@pytest.fixture
+def tmp_src(src_dir, tmp_path):
+    """Make a copy of the source dir under `$tmp/src`.
+
+    This fixture is useful whenever it's necessary to run `setup.py`
+    or `pip install` against the source directory when there's no
+    control over the number of simultaneous invocations. Such
+    concurrent runs create and delete directories with the same names
+    under the target directory and so they influence each other's runs
+    when they are not being executed sequentially.
+    """
+    tmp_src_path = tmp_path / 'src'
+    shutil.copytree(src_dir, tmp_src_path)
+    return tmp_src_path

setuptools/tests/test_virtualenv.py

@@ -85,7 +85,7 @@ def _get_pip_versions():
 
 
 @pytest.mark.parametrize('pip_version', _get_pip_versions())
-def test_pip_upgrade_from_source(pip_version, virtualenv):
+def test_pip_upgrade_from_source(pip_version, tmp_src, virtualenv):
     """
     Check pip can upgrade setuptools from source.
     """
@@ -104,7 +104,7 @@ def test_pip_upgrade_from_source(pip_version, virtualenv):
     virtualenv.run(' && '.join((
         'python setup.py -q sdist -d {dist}',
         'python setup.py -q bdist_wheel -d {dist}',
-    )).format(dist=dist_dir), cd=SOURCE_DIR)
+    )).format(dist=dist_dir), cd=tmp_src)
     sdist = glob.glob(os.path.join(dist_dir, '*.zip'))[0]
     wheel = glob.glob(os.path.join(dist_dir, '*.whl'))[0]
     # Then update from wheel.