Parallelize the test runs via pytest-xdist

changelog.d/2459.change.rst

@@ -0,0 +1 @@
+Tests now run in parallel via pytest-xdist, completing in about half the time. Special thanks to :user:`webknjaz` for hard work implementing test isolation. To run without parallelization, disable the plugin with ``tox -- -p no:xdist``.

pyproject.toml

@@ -24,6 +24,9 @@ addopts = "--flake8"
 [pytest.enabler.cov]
 addopts = "--cov"
 
+[pytest.enabler.xdist]
+addopts = "-n auto"
+
 [tool.towncrier]
     package = "setuptools"
     package_dir = "setuptools"

setup.cfg

@@ -47,7 +47,7 @@ testing =
 	pytest-black >= 0.3.7; python_implementation != "PyPy"
 	pytest-cov
 	pytest-mypy; python_implementation != "PyPy"
-	pytest-enabler
+	pytest-enabler >= 1.0.1
 
 	# local
     mock
@@ -58,6 +58,7 @@ testing =
     paver
     pip>=19.1 # For proper file:// URLs support.
     jaraco.envs
+    pytest-xdist
 
 docs =
     # Keep these in sync with docs/requirements.txt

setuptools/tests/fixtures.py

@@ -1,3 +1,7 @@
+import contextlib
+import sys
+import shutil
+
 import pytest
 
 from . import contexts
@@ -21,3 +25,36 @@ def user_override(monkeypatch):
 def tmpdir_cwd(tmpdir):
     with tmpdir.as_cwd() as orig:
         yield orig
+
+
+@pytest.fixture
+def tmp_src(request, 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(request.config.rootdir, tmp_src_path)
+    return tmp_src_path
+
+
+@pytest.fixture(autouse=True, scope="session")
+def workaround_xdist_376(request):
+    """
+    Workaround pytest-dev/pytest-xdist#376
+
+    ``pytest-xdist`` tends to inject '' into ``sys.path``,
+    which may break certain isolation expectations.
+    Remove the entry so the import
+    machinery behaves the same irrespective of xdist.
+    """
+    if not request.config.pluginmanager.has_plugin('xdist'):
+        return
+
+    with contextlib.suppress(ValueError):
+        sys.path.remove('')

setuptools/tests/test_build_meta.py

@@ -11,7 +11,7 @@
 
 
 class BuildBackendBase:
-    def __init__(self, cwd=None, env={}, backend_name='setuptools.build_meta'):
+    def __init__(self, cwd='.', env={}, backend_name='setuptools.build_meta'):
         self.cwd = cwd
         self.env = env
         self.backend_name = backend_name
@@ -126,7 +126,7 @@ class TestBuildMetaBackend:
     backend_name = 'setuptools.build_meta'
 
     def get_build_backend(self):
-        return BuildBackend(cwd='.', backend_name=self.backend_name)
+        return BuildBackend(backend_name=self.backend_name)
 
     @pytest.fixture(params=defns)
     def build_backend(self, tmpdir, request):
@@ -337,7 +337,7 @@ def test_build_sdist_builds_targz_even_if_zip_indicated(self, tmpdir_cwd):
     def test_build_sdist_relative_path_import(self, tmpdir_cwd):
         build_files(self._relative_path_import_files)
         build_backend = self.get_build_backend()
-        with pytest.raises(ImportError):
+        with pytest.raises(ImportError, match="^No module named 'hello'$"):
             build_backend.build_sdist("temp")
 
     @pytest.mark.parametrize('setup_literal, requirements', [

setuptools/tests/test_distutils_adoption.py

@@ -21,10 +21,10 @@ def run(self, cmd, *args, **kwargs):
 
 
 @pytest.fixture
-def venv(tmpdir):
+def venv(tmp_path, tmp_src):
     env = VirtualEnv()
-    env.root = path.Path(tmpdir)
-    env.req = os.getcwd()
+    env.root = path.Path(tmp_path / 'venv')
+    env.req = str(tmp_src)
     return env.create()
 
 

setuptools/tests/test_virtualenv.py

@@ -43,11 +43,11 @@ def bare_virtualenv():
 SOURCE_DIR = os.path.join(os.path.dirname(__file__), '../..')
 
 
-def test_clean_env_install(bare_virtualenv):
+def test_clean_env_install(bare_virtualenv, tmp_src):
     """
     Check setuptools can be installed in a clean environment.
     """
-    bare_virtualenv.run(['python', 'setup.py', 'install'], cd=SOURCE_DIR)
+    bare_virtualenv.run(['python', 'setup.py', 'install'], cd=tmp_src)
 
 
 def _get_pip_versions():
@@ -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.