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Pytest tests cannot load global config that definitely exists even though real use of the library can #1467
Description
While working on and writing tests for #1466, I discovered that Config.get_global_config raised an IOError in my test. Confused as to why that didn't break other tests, I searched for use of this in the tests and found this:
def test_global_config() -> None:
try:
assert Config.get_global_config() is not None
except IOError:
# There is no user config
pass
def test_system_config() -> None:
try:
assert Config.get_system_config() is not None
except IOError:
# There is no system config
pass
I changed these tests to this so that these situations result in an official "skip" with information about why it was skipped, instead of just silently fake-passing:
def test_global_config() -> None:
try:
assert Config.get_global_config() is not None
except IOError as e:
settings = Settings()
pytest.skip(f'Unavailable for testing with home dir = {settings.homedir}: {e}')
def test_system_config() -> None:
try:
assert Config.get_system_config() is not None
except IOError as e:
pytest.skip(f'Unavailable for testing: {e}')
But the resulting pytest output puzzled me:
test/test_config.py::test_global_config SKIPPED (Unavailable for testing with home dir = /Users/nicholas: the global file '.gitconfig' doesn't exist:)
test/test_config.py::test_system_config SKIPPED (Unavailable for testing: the system file 'gitconfig' doesn't exist:)
The first reason it puzzled me is that /Users/nicholas/.gitconfig definitely exists:
$ ls -al /Users/nicholas/.gitconfig
-rw-r--r-- 1 nicholas staff 366 Apr 9 17:39 /Users/nicholas/.gitconfig
The second reason it puzzled me is that I don't encounter this error if I simply use the library in a Python shell prompt:
>>> c = pygit2.Config.get_global_config()
>>> c["push.gpgSign"]
'if-asked'
Now, it's correct that my system config file does not exist:
>>> pygit2.Config.get_system_config()
Traceback (most recent call last):
File "<python-input-8>", line 1, in <module>
pygit2.Config.get_system_config()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "/Users/nicholas/Development/OSS/libgit2/pygit2/.venv/lib/python3.14/site-packages/pygit2/config.py", line 309, in get_system_config
check_error(err)
~~~~^^^^^
File "/Users/nicholas/Development/OSS/libgit2/pygit2/.venv/lib/python3.14/site-packages/pygit2/config.py", line 300, in _from_found_config
File "/Users/nicholas/Development/OSS/libgit2/pygit2/.venv/lib/python3.14/site-packages/pygit2/errors.py", line 56, in check_error
raise IOError(message)
OSError: the system file 'gitconfig' doesn't exist: No such file or directory
But note that that error message is slightly different from the skip message of the test: "No such file or directory" is missing in the skip message. Weird?
If I now manually create /etc/gitconfig:
>>> c = pygit2.Config.get_system_config()
>>> c["bogus.foo"]
'bar'
But, low and behold, that test, also, still skips with the same partial message about not finding the system config file.
So, these two functions do work ... just not in tests. I've been unable to figure out why. My best guess is that mypy is somehow sandboxed so that it can't read these files? But that's just a wild guess. I can't confirm it.
Activity
beamerblvd commentedon Jun 26, 2026
Still investigating this. Looks like the ": " followed by "No such file or directory" is coming from these lines in
libgit2. This indicates that the "No such file or directory" is coming from the OS (viastrerror), but in thepytestcase,strerroris returning nothing (or so it seems).There could be three reasons for this:
errnoto 0 between when the error occurred andgit_error_vsetusederrno(not clear how that could have happened, but it's possible ... it wasn't another thread, becauseerrnois thread-safe).strerroritself encountered an error (and so it seterrnoand returned a pointer to an empty string).strerrorwas called in another thread between when it returns at this point and whengit_str_putcopies the string at the resulting pointer, which would result in undefined behavior becausestrerroris not thread-safe and subsequent calls modify the same pointer previously returned (libgit2should not be using this and should instead be usingstrerror_r).strerrordoesn't return an empty string for unknown error codes. It returns "Unknown error nnn." So it's not an unknown error code.