bpo-40503: PEP 615: Tests and implementation for zoneinfo (GH-19909)
This is the initial implementation of PEP 615, the zoneinfo module,
ported from the standalone reference implementation (see
https://www.python.org/dev/peps/pep-0615/#reference-implementation for a
link, which has a more detailed commit history).
This includes (hopefully) all functional elements described in the PEP,
but documentation is found in a separate PR. This includes:
1. A pure python implementation of the ZoneInfo class
2. A C accelerated implementation of the ZoneInfo class
3. Tests with 100% branch coverage for the Python code (though C code
coverage is less than 100%).
4. A compile-time configuration option on Linux (though not on Windows)
Differences from the reference implementation:
- The module is arranged slightly differently: the accelerated module is
`_zoneinfo` rather than `zoneinfo._czoneinfo`, which also necessitates
some changes in the test support function. (Suggested by Victor
Stinner and Steve Dower.)
- The tests are arranged slightly differently and do not include the
property tests. The tests live at test/test_zoneinfo/test_zoneinfo.py
rather than test/test_zoneinfo.py or test/test_zoneinfo/__init__.py
because we may do some refactoring in the future that would likely
require this separation anyway; we may:
- include the property tests
- automatically run all the tests against both pure Python and C,
rather than manually constructing C and Python test classes (similar
to the way this works with test_datetime.py, which generates C
and Python test cases from datetimetester.py).
- This includes a compile-time configuration option on Linux (though not
on Windows); added with much help from Thomas Wouters.
- Integration into the CPython build system is obviously different from
building a standalone zoneinfo module wheel.
- This includes configuration to install the tzdata package as part of
CI, though only on the coverage jobs. Introducing a PyPI dependency as
part of the CI build was controversial, and this is seen as less of a
major change, since the coverage jobs already depend on pip and PyPI.
Additional changes that were introduced as part of this PR, most / all of
which were backported to the reference implementation:
- Fixed reference and memory leaks
With much debugging help from Pablo Galindo
- Added smoke tests ensuring that the C and Python modules are built
The import machinery can be somewhat fragile, and the "seamlessly falls
back to pure Python" nature of this module makes it so that a problem
building the C extension or a failure to import the pure Python version
might easily go unnoticed.
- Adjustments to zoneinfo.__dir__
Suggested by Petr Viktorin.
- Slight refactorings as suggested by Steve Dower.
- Removed unnecessary if check on std_abbr
Discovered this because of a missing line in branch coverage.diff --git a/Modules/Setup b/Modules/Setup
index 87e73ba..02cfb67 100644
--- a/Modules/Setup
+++ b/Modules/Setup
@@ -181,6 +181,7 @@
#_elementtree -I$(srcdir)/Modules/expat -DHAVE_EXPAT_CONFIG_H -DUSE_PYEXPAT_CAPI _elementtree.c # elementtree accelerator
#_pickle _pickle.c # pickle accelerator
#_datetime _datetimemodule.c # datetime accelerator
+#_zoneinfo _zoneinfo.c # zoneinfo accelerator
#_bisect _bisectmodule.c # Bisection algorithms
#_heapq _heapqmodule.c # Heap queue algorithm
#_asyncio _asynciomodule.c # Fast asyncio Future