Merge pull request #3133 from befeleme/fix-tests-for-fedora

Tests using virtual environments: pass the copy of existing env to the subprocesses

3 files changed, 26 insertions, 1 deletions

diff --git a/changelog.d/3133.misc.rst b/changelog.d/3133.misc.rst
new file mode 100644
index 00000000..3377e061
--- /dev/null
+++ b/changelog.d/3133.misc.rst
@@ -0,0 +1 @@
+Enhanced isolation of tests using virtual environments - PYTHONPATH is not leaking to spawned subprocesses  -- by :user:`befeleme`
diff --git a/setuptools/tests/environment.py b/setuptools/tests/environment.py
index a0c0ec6e..bcf29601 100644
--- a/setuptools/tests/environment.py
+++ b/setuptools/tests/environment.py
@@ -18,6 +18,19 @@ class VirtualEnv(jaraco.envs.VirtualEnv):
     def run(self, cmd, *args, **kwargs):
         cmd = [self.exe(cmd[0])] + cmd[1:]
         kwargs = {"cwd": self.root, **kwargs}  # Allow overriding
+        # In some environments (eg. downstream distro packaging), where:
+        # - tox isn't used to run tests and
+        # - PYTHONPATH is set to point to a specific setuptools codebase and
+        # - no custom env is explicitly set by a test
+        # PYTHONPATH will leak into the spawned processes.
+        # In that case tests look for module in the wrong place (on PYTHONPATH).
+        # Unless the test sets its own special env, pass a copy of the existing
+        # environment with removed PYTHONPATH to the subprocesses.
+        if "env" not in kwargs:
+            env = dict(os.environ)
+            if "PYTHONPATH" in env:
+                del env["PYTHONPATH"]
+            kwargs["env"] = env
         return subprocess.check_output(cmd, *args, **kwargs)
 
 
diff --git a/setuptools/tests/fixtures.py b/setuptools/tests/fixtures.py
index 7599e655..e912399d 100644
--- a/setuptools/tests/fixtures.py
+++ b/setuptools/tests/fixtures.py
@@ -98,7 +98,18 @@ def venv(tmp_path, setuptools_wheel):
     env = environment.VirtualEnv()
     env.root = path.Path(tmp_path / 'venv')
     env.req = str(setuptools_wheel)
-    return env.create()
+    # In some environments (eg. downstream distro packaging),
+    # where tox isn't used to run tests and PYTHONPATH is set to point to
+    # a specific setuptools codebase, PYTHONPATH will leak into the spawned
+    # processes.
+    # env.create() should install the just created setuptools
+    # wheel, but it doesn't if it finds another existing matching setuptools
+    # installation present on PYTHONPATH:
+    # `setuptools is already installed with the same version as the provided
+    # wheel. Use --force-reinstall to force an installation of the wheel.`
+    # This prevents leaking PYTHONPATH to the created environment.
+    with contexts.environment(PYTHONPATH=None):
+        return env.create()
 
 
 @pytest.fixture