tests: better support for parallel testing (#871)

* tests: better support for parallel testing

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* tests: only copy setuptools

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* Update tests/conftest.py

Co-authored-by: layday <layday@protonmail.com>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: layday <layday@protonmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 3 people

tests/conftest.py

@@ -12,11 +12,14 @@
 import tempfile
 
 from functools import partial, update_wrapper
+from pathlib import Path
 
 import pytest
 
 import build.env
 
+from build._compat import tomllib
+
 
 def pytest_addoption(parser):
     os.environ['PYTHONWARNINGS'] = 'ignore:DEPRECATION::pip._internal.cli.base_command'  # for when not run within tox
@@ -101,10 +104,28 @@ def packages_path():
     return os.path.realpath(os.path.join(__file__, '..', 'packages'))
 
 
+def is_setuptools(package_path):
+    if package_path.joinpath('setup.py').is_file():
+        return True
+    pyproject = package_path / 'pyproject.toml'
+    try:
+        with pyproject.open('rb') as f:
+            pp = tomllib.load(f)
+    except (FileNotFoundError, ValueError):
+        return True
+    return 'setuptools' in pp.get('build-system', {}).get('build-backend', 'setuptools')
+
+
 def generate_package_path_fixture(package_name):
     @pytest.fixture
-    def fixture(packages_path):
-        return os.path.join(packages_path, package_name)
+    def fixture(packages_path, tmp_path):
+        package_path = Path(packages_path) / package_name
+        if not is_setuptools(package_path):
+            return str(package_path)
+
+        new_path = tmp_path / package_name
+        shutil.copytree(package_path, new_path)
+        return str(new_path)
 
     return fixture