unittest discover throws TypeError on namespace packages · Issue #80958 · python/cpython · GitHub

BPO	36777
Nosy	@warsaw, @brettcannon, @ericvsmith, @rbtcollins, @ezio-melotti, @voidspace, @methane, @augustogoulart, @tirkarthi
PRs	bpo-36777: unittest discover should not throw TypeError on empty packages #13259

Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-05-02.16:47:03.266>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = 'unittest discover throws TypeError on namespace packages'
updated_at = <Date 2020-07-20.03:33:05.899>
user = 'https://github.com/tirkarthi'

bugs.python.org fields:

activity = <Date 2020-07-20.03:33:05.899>
actor = 'methane'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-05-02.16:47:03.266>
creator = 'xtreak'
dependencies = []
files = []
hgrepos = []
issue_num = 36777
keywords = ['patch']
message_count = 5.0
messages = ['341285', '341339', '341530', '373941', '373980']
nosy_count = 9.0
nosy_names = ['barry', 'brett.cannon', 'eric.smith', 'rbcollins', 'ezio.melotti', 'michael.foord', 'methane', 'augustogoulart', 'xtreak']
pr_nums = ['13259']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue36777'
versions = ['Python 3.7', 'Python 3.8']

Linked PRs

gh-80958: Restore unittest discovery support for namespace packages as start directory #123820

In the given folder structure unittest discover fails. I think this is due to bpo-32303 where __file__ was set as None and I guess empty packages didn't have __file__ set before which has None value now. Hence the_module.__file__ returns None and thus subsequent calls to os.path.dirname raise TypeError. There is one another location in the same file in unittest module causing this issue. See also bpo-36406 for similar error in doctest with the change. I reverted bbbcf86 just to confirm the issue. I am adding devs in bpo-32303 and unittest. Any thoughts on this would be helpful.

➜  cpython git:(master) ✗ tree test1
test1
└── test2
    └── test_foo.py

1 directory, 1 file
➜  cpython git:(master) ✗ ./python.exe -m unittest discover test1.test2
Traceback (most recent call last):
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/runpy.py", line 192, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/__main__.py", line 18, in <module>
    main(module=None)
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/main.py", line 100, in __init__
    self.parseArgs(argv)
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/main.py", line 124, in parseArgs
    self._do_discovery(argv[2:])
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/main.py", line 244, in _do_discovery
    self.createTests(from_discovery=True, Loader=Loader)
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/main.py", line 154, in createTests
    self.test = loader.discover(self.start, self.pattern, self.top)
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/unittest/loader.py", line 306, in discover
    os.path.dirname((the_module.__file__)))
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/posixpath.py", line 152, in dirname
    p = os.fspath(p)
TypeError: expected str, bytes or os.PathLike object, not NoneType

# 3.6.4 works that doesn't have the change

➜ cpython git:(master) ✗ python3.6 -m unittest discover test1.test2
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

A unittest would be as below :

def test_empty_package_discovery(self):
    # bpo-36789: Return zero test cases when using discovery in
    # empty packages.

    with support.temp_dir() as path:
        dirname, basename = os.path.split(path)
        os.mkdir(os.path.join(path, 'test2'))

        with support.DirsOnSysPath(dirname):
            loader = unittest.TestLoader()
            empty_package = f"{basename}.test2"
            tests_count = loader.discover(empty_package).countTestCases()
            self.assertEqual(loader.discover(empty_package).countTestCases(), 0)

One possible fix would be to check for __file__ == None and return empty list of test cases but this causes a behavior change like below where my patch returns 0 and python 3.6 returns 1 test.

# Patch

diff --git a/Lib/unittest/loader.py b/Lib/unittest/loader.py
index ba7105e1ad..f465b2419f 100644
--- a/Lib/unittest/loader.py
+++ b/Lib/unittest/loader.py
@@ -302,6 +302,10 @@ class TestLoader(object):
                 the_module = sys.modules[start_dir]
                 top_part = start_dir.split('.')[0]
                 try:
+                    filepath = the_module.__file__
+                    # __file__ is None for empty packages. Hence return empty list of tests.
+                    if filepath == None:
+                        return self.suiteClass([])
                     start_dir = os.path.abspath(
                        os.path.dirname((the_module.__file__)))
                 except AttributeError:

# Behavior change

➜ cpython git:(unittest-empty-package) ✗ ./python.exe -m unittest discover test1.test2

----------------------------------------------------------------------
Ran 0 tests in 0.000s

OK
➜ cpython git:(unittest-empty-package) ✗ python3.6 -m unittest discover test1.test2
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

My patch also causes reference leak and I am not sure why. So I guess mine is not the best approach to solving this.

➜ cpython git:(unittest-empty-package) ✗ ./python.exe -m test --fail-env-changed -R 3:3 test_unittest
Run tests sequentially
0:00:00 load avg: 1.46 [1/1] test_unittest
beginning 6 repetitions
123456
......
test_unittest leaked [99, 99, 99] references, sum=297
test_unittest leaked [38, 38, 38] memory blocks, sum=114
test_unittest failed in 43 sec 634 ms

== Tests result: FAILURE ==

1 test failed:
test_unittest

Total duration: 43 sec 655 ms
Tests result: FAILURE

I opened bpo-36784 for reference leak in the initial report along with a reproducer that is reproducible on master branch without my changes.

Confirming that the issue seems to have been introduced on 3.7. Working on this at the PyCon US 2019 sprints.

I didn't know packages without __init__.py are namespace packages back then and used empty packages. I guess it's related to the other issues with unittest and namespace packages bpo-36723, bpo-23882 and bpo-35617

This issue is not duplicate of bpo-23882.
In the example, test1 and test1.test2 are namespace package. But they are specified explicitly.

./python.exe -m unittest discover test1.test2

ran this through an ai to diagnose and got this suggested patch

diff --git a/Lib/unittest/loader.py b/Lib/unittest/loader.py
index ba7105e1ad..f465b2419f 100644
--- a/Lib/unittest/loader.py
+++ b/Lib/unittest/loader.py
@@ -302,6 +302,13 @@ class TestLoader(object):
                 the_module = sys.modules[start_dir]
                 top_part = start_dir.split('.')[0]
                 try:
+                    # Handle the case where __file__ is None (empty package)
+                    if the_module.__file__ is None:
+                        if not hasattr(the_module, '__path__') or not list(the_module.__path__):
+                            # If the package is empty, return an empty suite
+                            return self.suiteClass([])
+                        # Continue processing if it's not empty
+                        
                     start_dir = os.path.abspath(
                        os.path.dirname(the_module.__file__))
                 except AttributeError:

which came with this explanation:

Check for file: The patch first checks if file is None. If it is, it further checks if the package is truly empty by examining path (which should exist for packages).
Return Empty Suite Only if Empty: If both conditions confirm that the package is empty, it returns an empty test suite. Otherwise, it proceeds with the normal discovery process.
Avoid Reference Leaks: The refined patch avoids creating unnecessary TestSuite objects, which helps in preventing reference leaks.
Additional Testing:
After applying the patch, it is crucial to run extensive tests, including the specific cases of empty packages and reference management, to ensure no new issues are introduced and that the fix resolves the original problem.

pythongh-80958: Restore unittest discovery of PEP 420 namespace packages

Support for namespace package discovery was removed in #29745, however as noted in this issue, we still have a cryptic failure.

I think we should consider reverting #29745 and solving the underlying issue, which was pretty trivial.

PR

@jacobtylerwalls Do you understand that test discovery in namespace packages had been broken for long time before I remove?
Reverting #29745 just re-introduce broken feature again.

Update: I was wrong, suggested patch is not enough and code removed in #29745 seems needed.
But I need more time to understand test discovery codebase again.

fixup! pythongh-80958: Restore unittest discovery of PEP 420 namespac…

I agree there is no reason to do a revert alone without fixing what was broken about it. Subsequent commits on #29745 apply a fix. Sorry if this was not signalled sufficiently.

But I need more time to understand test discovery codebase again.

Take your time, I'm eager to have your view when you are able, and thanks!

gh-80958: unittest: discovery support for namespace packages as start…

pythongh-80958: unittest: discovery support for namespace packages as…

unittest discover throws TypeError on namespace packages · Issue #80958 · python/cpython · GitHub

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unittest discover throws TypeError on namespace packages · Issue #80958 · python/cpython · GitHub

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unittest discover throws TypeError on namespace packages #80958

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tirkarthi commented on May 2, 2019

tirkarthi commented on May 3, 2019

augustogoulart commented on May 6, 2019

tirkarthi commented on Jul 19, 2020

methane commented on Jul 20, 2020

DataAcctLisa commented on Sep 2, 2024

jacobtylerwalls commented on Sep 7, 2024

methane commented on Sep 8, 2024

jacobtylerwalls commented on Sep 8, 2024

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