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test_urllib2.HandlerTests.test_redirect_no_path fails when proxy environment variables are set #148919
Description
Bug report
Bug description:
Running:
./python -m unittest test.test_urllib2.HandlerTests.test_redirect_no_path
can fail in environments where proxy-related variables are set (http_proxy, https_proxy, etc.).
The test output shows below:
F
======================================================================
FAIL: test_redirect_no_path (test.test_urllib2.HandlerTests.test_redirect_no_path)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/yansendao/git/cpython/Lib/test/test_urllib2.py", line 1400, in test_redirect_no_path
fp = urllib.request.urlopen("http://python.org/path")
File "/home/yansendao/git/cpython/Lib/urllib/request.py", line 187, in urlopen
return opener.open(url, data, timeout)
~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
File "/home/yansendao/git/cpython/Lib/urllib/request.py", line 489, in open
response = self._open(req, data)
File "/home/yansendao/git/cpython/Lib/urllib/request.py", line 506, in _open
result = self._call_chain(self.handle_open, protocol, protocol +
'_open', req)
File "/home/yansendao/git/cpython/Lib/urllib/request.py", line 466, in _call_chain
result = func(*args)
File "/home/yansendao/git/cpython/Lib/urllib/request.py", line 1352, in http_open
return self.do_open(http.client.HTTPConnection, req)
~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/yansendao/git/cpython/Lib/urllib/request.py", line 1323, in do_open
h.request(req.get_method(), req.selector, req.data, headers,
~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
encode_chunked=req.has_header('Transfer-encoding'))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/yansendao/git/cpython/Lib/test/test_urllib2.py", line 1395, in request
self.assertEqual(url, next(urls))
~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
AssertionError: 'http://python.org/path' != '/path'
- http://python.org/path
+ /path
----------------------------------------------------------------------
Ran 1 test in 0.010s
FAILED (failures=1)
Expected behavior
This test should validate relative redirect behavior (Location: ?query) independently of external shell/network configuration. It should pass regardless of whether proxy env vars are present.
Root cause
urllib.request.urlopen() honors proxy settings from environment variables.
When proxying is enabled, the HTTP request target format changes to absolute-form, which does not match this test’s path-only assertion.
Proposed fix
Make the test environment-independent by clearing proxy-related environment variables inside test_redirect_no_path using EnvironmentVarGuard (both lower/upper case variants, plus no_proxy/NO_PROXY).
Why proxy configuration matters when running tests
Some environments (corporate/campus networks, CI runners) require proxy settings for outbound connectivity; without them, networked tests may fail due to connection/timeouts.
However, logic-focused unit tests should not depend on external proxy state, so they should explicitly isolate themselves from proxy env effects.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Linked PRs
- gh-148919: Make test_redirect_no_path independent of proxy environment variables #148920
- [3.15] gh-148919: Make test_redirect_no_path independent of proxy environment variables (GH-148920) #160846
- [3.14] gh-148919: Make test_redirect_no_path independent of proxy environment variables (GH-148920) #160847
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Merge branch 'main' into pythongh-148919
Merge branch 'main' into pythongh-148919
pythongh-148919: Also make test_redirect_encoding independent of prox…
gh-148919: Make test_redirect_no_path independent of proxy environmen…
[3.15] gh-148919: Make test_redirect_no_path independent of proxy env…
[3.14] gh-148919: Make test_redirect_no_path independent of proxy env…