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gh-124529: Fix _strptime to make %c/%x accept a year with fewer digits #124778

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gh-124529: Fix _strptime to make %c/%x accept a year with fewer digits #124778

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827db45
gh-124529: Fix _strptime to make %c/%x accept year with fewer digits
zuo Sep 30, 2024
1d916a0
Add the blurb
zuo Sep 30, 2024
a4ba3c9
Fix/improve (and shorten) the blurb
zuo Sep 30, 2024
cef0722
Fix/improve/refactor tests and restrict their scope
zuo Sep 30, 2024
6556bdf
Test fail message fixes
zuo Sep 30, 2024
56c84dc
Continue enhancing/improving tests
zuo Sep 30, 2024
b42783c
Improve docstring
zuo Sep 30, 2024
97b523e
Add a suitable mention in the docs + improve blurb
zuo Sep 30, 2024
6c2addf
Docstring edit
zuo Sep 30, 2024
fb32c03
Edit the mention in the docs
zuo Sep 30, 2024
722efe4
Minor docs edit
zuo Sep 30, 2024
7b46a48
Fix/improve tests
zuo Oct 1, 2024
3d4116a
Shorten blurb again
zuo Oct 1, 2024
8eac106
Minor docs edit
zuo Oct 1, 2024
1956662
Docstring edit
zuo Oct 1, 2024
a77c3da
Docs edit
zuo Oct 1, 2024
b3b161f
Docstring edit
zuo Oct 1, 2024
949e66a
Minor test improvements/refactoring
zuo Oct 1, 2024
059d4c5
Add `time.strptime()`-dedicated test
zuo Oct 1, 2024
95753ac
Minor test improvements/refactoring
zuo Oct 1, 2024
ed4582b
Merge branch 'main' into strptime-c-and-y-fix
zuo Oct 1, 2024
990b075
Minor test improvement
zuo Oct 1, 2024
ecc359d
Test improvements/refactoring
zuo Oct 1, 2024
6d690ca
Minor refactoring
zuo Oct 1, 2024
4ad1062
Merge branch 'main' into strptime-c-and-y-fix
zuo Oct 1, 2024
c79a66b
Apply suggestion from @donbarbos
zuo Jul 18, 2026
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Test improvements/refactoring
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@zuo
zuo committed Oct 1, 2024
commit ecc359de010d06fed3c65197280a33ef46ac31dd
26 changes: 12 additions & 14 deletions Lib/test/datetimetester.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2129,18 +2129,18 @@ def test_strftime_strptime_roundtrip_concerning_locale_specific_year(self):
concerned_formats = '%c', '%x'

def run_subtest():
input_ = sample.replace(year=year)
input_obj = sample.replace(year=year)
reason = (f"test strftime/strptime roundtrip concerning "
f"locale-specific year representation "
f"- for {fmt=} and {input_=}")
f"- for {fmt=} and {input_obj=}")
fail_msg = f"{reason} - failed"
with self.subTest(reason=reason):
formatted = input_.strftime(fmt)
formatted = input_obj.strftime(fmt)
try:
parsed = self.theclass.strptime(formatted, fmt)
except ValueError as exc:
self.fail(f"{fail_msg}; parsing error: {exc!r}")
self.assertEqual(parsed, input_, fail_msg)
self.assertEqual(parsed, input_obj, fail_msg)

sample = self.theclass.strptime('1999-03-17', '%Y-%m-%d')
for fmt in concerned_formats:
Expand All @@ -2161,11 +2161,10 @@ def run_subtest():
]:
run_subtest()
else:
self.fail(f"it seems that sample.strftime({fmt!r})="
f"{sample_str!r} does not include year="
f"{sample.year!r} in any expected format "
f"(is there something severely wrong with "
f"current locale?)")
self.fail(f"{sample!r}.strftime({fmt!r})={sample_str!r} "
f"does not include year={sample.year!r} in "
f"any expected format (is there something "
f"severely wrong with the current locale?)")

def test_strptime_accepting_locale_specific_year_with_fewer_digits(self):
# gh-124529
Expand Down Expand Up @@ -2198,11 +2197,10 @@ def run_subtest():
year_digits = str(year - 2000)
run_subtest()
else:
self.fail(f"it seems that sample.strftime({fmt!r})="
f"{sample_str!r} does not include year="
f"{sample.year!r} in any expected format "
f"(is there something severely wrong with "
f"current locale?)")
self.fail(f"{sample!r}.strftime({fmt!r})={sample_str!r} "
f"does not include year={sample.year!r} in "
f"any expected format (is there something "
f"severely wrong with the current locale?)")


#############################################################################
Expand Down
106 changes: 53 additions & 53 deletions Lib/test/test_strptime.py
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Original file line number Diff line number Diff line change
Expand Up @@ -172,14 +172,11 @@ def test_compile(self):
fmt = "%" + directive
with self.subTest(f"{fmt!r} should match input containing "
f"year with fewer digits than usual"):
(input_string,
year) = _get_data_to_test_strptime_with_few_digits_year(fmt)
if year is None:
self.fail(f"it seems that using {fmt=} results in value "
f"which does not include year representation "
f"in any expected format (is there something "
f"severely wrong with current locale?)")

try:
(input_string,
_) = _get_data_to_test_strptime_with_few_digits_year(fmt)
except AssertionError as exc:
self.fail(str(exc))
compiled = self.time_re.compile(fmt)
found = compiled.match(input_string)
self.assertTrue(found,
Expand All @@ -189,13 +186,11 @@ def test_compile(self):
fmt = "%" + directive
with self.subTest(f"{fmt!r} should not match input containing "
f"year with fewer digits than usual"):
(input_string,
year) = _get_data_to_test_strptime_with_few_digits_year(fmt)
if year is None:
self.fail(f"it seems that using {fmt=} results in value "
f"which does not include year representation "
f"in any expected format (is there something "
f"severely wrong with current locale?)")
try:
(input_string,
_) = _get_data_to_test_strptime_with_few_digits_year(fmt)
except AssertionError as exc:
self.fail(str(exc))
compiled = self.time_re.compile(fmt)
found = compiled.match(input_string)
self.assertFalse(found,
Expand Down Expand Up @@ -337,13 +332,14 @@ def helper(self, directive, position):

def helper_for_directives_accepting_few_digits_year(self, directive):
fmt = "%" + directive
(input_string,
expected_year) = _get_data_to_test_strptime_with_few_digits_year(fmt)
if expected_year is None:
self.fail(f"it seems that using {fmt=} results in value "
f"which does not include year representation "
f"in any expected format (is there something "
f"severely wrong with current locale?)")

try:
(input_string,
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expected_year,
) = _get_data_to_test_strptime_with_few_digits_year(fmt)
except AssertionError as exc:
self.fail(str(exc))

try:
output_year = _strptime._strptime(input_string, fmt)[0][0]
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except ValueError as exc:
Expand Down Expand Up @@ -853,47 +849,51 @@ def _get_data_to_test_strptime_with_few_digits_year(fmt):
# where:
# * <strptime input string> -- is a `strftime(fmt)`-result-like str
# containing a year number which is *shorter* than the usual four
# or two digits (namely: here the contained year number consist of
# one digit: 7; that's an arbitrary choice);
# or two digits, because the number is small and *not* 0-padded
# (namely: here the contained year number consist of one digit: 7
# -- that's an arbitrary choice);
# * <expected year> -- is an int representing the year number that
# is expected to be part of the result of a `strptime(<strptime
# input string>, fmt)` call (namely: either 7 or 2007, depending
# on the given format string and current locale...); however, it
# is None if <strptime input string> does *not* contain the year
# part (for the given format string and current locale).
# on the given format string and current locale...).
# Note: AssertionError (with an appropriate failure message) is
# raised if <strptime input string> does *not* contain the year
# part (for the given format string and current locale).

# 1. Prepare auxiliary *magic* time data (note that the magic values
# 1. Prepare auxiliary sample time data (note that the magic values
# we use here are guaranteed to be compatible with `time.strftime()`,
# and are also intended to be well distinguishable within a formatted
# string, thanks to the fact that the amount of overloaded numbers is
# minimized, as in `_strptime.LocaleTime.__calc_date_time()`):
magic_year = 1999
magic_tt = (magic_year, 3, 17, 22, 44, 55, 2, 76, 0)
# and are also intended to be well distinguishable within formatted
# strings, thanks to the fact that the amount of overloaded numbers
# is minimized, as in `_strptime.LocaleTime.__calc_date_time()`):
sample_year = 1999
sample_tt = (sample_year, 3, 17, 22, 44, 55, 2, 76, 0)
sample_str = time.strftime(fmt, sample_tt)
sample_year_4digits = str(sample_year)
sample_year_2digits = str(sample_year)[-2:]

# 2. Pick an arbitrary year number representation that
# is always *shorter* than the usual four or two digits:
input_year_str = '7'
year_1digit = '7'

# 3. Obtain the resultant 2-tuple:

input_string = time.strftime(fmt, magic_tt)
expected_year = None

magic_4digits = str(magic_year)
if found_4digits := (magic_4digits in input_string):
# `input_string` contains up-to-4-digit year representation
input_string = input_string.replace(magic_4digits, input_year_str)
expected_year = int(input_year_str)

magic_2digits = str(magic_year)[-2:]
if magic_2digits in input_string:
# `input_string` contains up-to-2-digit year representation
if found_4digits:
raise RuntimeError(f'case not supported by this helper: {fmt=} '
f'(includes both 2-digit and 4-digit year)')
input_string = input_string.replace(magic_2digits, input_year_str)
expected_year = 2000 + int(input_year_str)

if sample_year_4digits in sample_str:
input_string = sample_str.replace(sample_year_4digits, year_1digit)
if sample_year_2digits in input_string:
raise RuntimeError(f"the {fmt!r} format is not supported by "
f"this helper (a {fmt!r}-formatted string, "
f"{sample_str!r}, seems to include both a "
f"2-digit and 4-digit year number)")
expected_year = int(year_1digit)
elif sample_year_2digits in sample_str:
input_string = sample_str.replace(sample_year_2digits, year_1digit)
expected_year = 2000 + int(year_1digit)
else:
raise AssertionError(f"time.strftime({fmt!r}, ...)={sample_str!r} "
f"does not include the year {sample_year!r} in "
f"any expected format (are {fmt!r}-formatted "
f"strings supposed to include a year number? "
f"if they are, isn't there something severely "
f"wrong with the current locale?)")
return input_string, expected_year


Expand Down
9 changes: 4 additions & 5 deletions Lib/test/test_time.py
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Original file line number Diff line number Diff line change
Expand Up @@ -338,11 +338,10 @@ def run_subtest():
year_digits = str(year - 2000)
run_subtest()
else:
self.fail(f"it seems that time.strftime(fmt, ...)="
f"{sample_str!r} does not include year="
f"{sample_tt[0]!r} in any expected format "
f"(is there something severely wrong with "
f"current locale?)")
self.fail(f"time.strftime({fmt!r}, ...)={sample_str!r} "
f"does not include year={sample_tt[0]!r} in "
f"any expected format (is there something "
f"severely wrong with the current locale?)")

def test_asctime(self):
time.asctime(time.gmtime(self.t))
Expand Down