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[3.14] Improve tests for str to Fraction conversion (GH-134010) #134016

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Merged
merged 1 commit into from
May 14, 2025
+97 −110

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[3.14] Improve tests for str to Fraction conversion (GH-134010) #134016

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207 changes: 97 additions & 110 deletions Lib/test/test_fractions.py
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
"""Tests for Lib/fractions.py."""

from decimal import Decimal
from test.support import requires_IEEE_754
from test.support import requires_IEEE_754, adjust_int_max_str_digits
import math
import numbers
import operator
@@ -395,12 +395,14 @@ class B(metaclass=M):

def testFromString(self):
self.assertEqual((5, 1), _components(F("5")))
self.assertEqual((5, 1), _components(F("005")))
self.assertEqual((3, 2), _components(F("3/2")))
self.assertEqual((3, 2), _components(F("3 / 2")))
self.assertEqual((3, 2), _components(F(" \n +3/2")))
self.assertEqual((-3, 2), _components(F("-3/2 ")))
self.assertEqual((13, 2), _components(F(" 013/02 \n ")))
self.assertEqual((13, 2), _components(F(" 0013/002 \n ")))
self.assertEqual((16, 5), _components(F(" 3.2 ")))
self.assertEqual((16, 5), _components(F("003.2")))
self.assertEqual((-16, 5), _components(F(" -3.2 ")))
self.assertEqual((-3, 1), _components(F(" -3. ")))
self.assertEqual((3, 5), _components(F(" .6 ")))
@@ -419,116 +421,101 @@ def testFromString(self):
self.assertRaisesMessage(
ZeroDivisionError, "Fraction(3, 0)",
F, "3/0")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '3/'",
F, "3/")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '/2'",
F, "/2")
self.assertRaisesMessage(
# Denominators don't need a sign.
ValueError, "Invalid literal for Fraction: '3/+2'",
F, "3/+2")
self.assertRaisesMessage(
# Imitate float's parsing.
ValueError, "Invalid literal for Fraction: '+ 3/2'",
F, "+ 3/2")
self.assertRaisesMessage(
# Avoid treating '.' as a regex special character.
ValueError, "Invalid literal for Fraction: '3a2'",
F, "3a2")
self.assertRaisesMessage(
# Don't accept combinations of decimals and rationals.
ValueError, "Invalid literal for Fraction: '3/7.2'",
F, "3/7.2")
self.assertRaisesMessage(
# Don't accept combinations of decimals and rationals.
ValueError, "Invalid literal for Fraction: '3.2/7'",
F, "3.2/7")
self.assertRaisesMessage(
# Allow 3. and .3, but not .
ValueError, "Invalid literal for Fraction: '.'",
F, ".")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '_'",
F, "_")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '_1'",
F, "_1")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1__2'",
F, "1__2")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '/_'",
F, "/_")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1_/'",
F, "1_/")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '_1/'",
F, "_1/")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1__2/'",
F, "1__2/")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1/_'",
F, "1/_")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1/_1'",
F, "1/_1")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1/1__2'",
F, "1/1__2")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1._111'",
F, "1._111")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1.1__1'",
F, "1.1__1")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1.1e+_1'",
F, "1.1e+_1")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1.1e+1__1'",
F, "1.1e+1__1")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '123.dd'",
F, "123.dd")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '123.5_dd'",
F, "123.5_dd")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: 'dd.5'",
F, "dd.5")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '7_dd'",
F, "7_dd")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1/dd'",
F, "1/dd")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1/123_dd'",
F, "1/123_dd")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '789edd'",
F, "789edd")
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '789e2_dd'",
F, "789e2_dd")

def check_invalid(s):
msg = "Invalid literal for Fraction: " + repr(s)
self.assertRaisesMessage(ValueError, msg, F, s)

check_invalid("3/")
check_invalid("/2")
# Denominators don't need a sign.
check_invalid("3/+2")
check_invalid("3/-2")
# Imitate float's parsing.
check_invalid("+ 3/2")
check_invalid("- 3/2")
# Avoid treating '.' as a regex special character.
check_invalid("3a2")
# Don't accept combinations of decimals and rationals.
check_invalid("3/7.2")
check_invalid("3.2/7")
# No space around dot.
check_invalid("3 .2")
check_invalid("3. 2")
# No space around e.
check_invalid("3.2 e1")
check_invalid("3.2e 1")
# Fractional part don't need a sign.
check_invalid("3.+2")
check_invalid("3.-2")
# Only accept base 10.
check_invalid("0x10")
check_invalid("0x10/1")
check_invalid("1/0x10")
check_invalid("0x10.")
check_invalid("0x10.1")
check_invalid("1.0x10")
check_invalid("1.0e0x10")
# Only accept decimal digits.
check_invalid("³")
check_invalid("³/2")
check_invalid("3/²")
check_invalid("³.2")
check_invalid("3.²")
check_invalid("3.2e²")
check_invalid("¼")
# Allow 3. and .3, but not .
check_invalid(".")
check_invalid("_")
check_invalid("_1")
check_invalid("1__2")
check_invalid("/_")
check_invalid("1_/")
check_invalid("_1/")
check_invalid("1__2/")
check_invalid("1/_")
check_invalid("1/_1")
check_invalid("1/1__2")
check_invalid("1._111")
check_invalid("1.1__1")
check_invalid("1.1e+_1")
check_invalid("1.1e+1__1")
check_invalid("123.dd")
check_invalid("123.5_dd")
check_invalid("dd.5")
check_invalid("7_dd")
check_invalid("1/dd")
check_invalid("1/123_dd")
check_invalid("789edd")
check_invalid("789e2_dd")
# Test catastrophic backtracking.
val = "9"*50 + "_"
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '" + val + "'",
F, val)
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1/" + val + "'",
F, "1/" + val)
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1." + val + "'",
F, "1." + val)
self.assertRaisesMessage(
ValueError, "Invalid literal for Fraction: '1.1+e" + val + "'",
F, "1.1+e" + val)
check_invalid(val)
check_invalid("1/" + val)
check_invalid("1." + val)
check_invalid("." + val)
check_invalid("1.1+e" + val)
check_invalid("1.1e" + val)

def test_limit_int(self):
maxdigits = 5000
with adjust_int_max_str_digits(maxdigits):
val = '1' * maxdigits
num = (10**maxdigits - 1)/9
self.assertEqual((num, 1), _components(F(val)))
self.assertRaises(ValueError, F, val + '1')
self.assertEqual((num, 2), _components(F(val + '/2')))
self.assertRaises(ValueError, F, val + '1/2')
self.assertEqual((1, num), _components(F('1/' + val)))
self.assertRaises(ValueError, F, '1/1' + val)
self.assertEqual(((10**(maxdigits+1) - 1)/9, 10**maxdigits),
_components(F('1.' + val)))
self.assertRaises(ValueError, F, '1.1' + val)
self.assertEqual((num, 10**maxdigits), _components(F('.' + val)))
self.assertRaises(ValueError, F, '.1' + val)
self.assertRaises(ValueError, F, '1.1e1' + val)
self.assertEqual((11, 10), _components(F('1.1e' + '0' * maxdigits)))
self.assertRaises(ValueError, F, '1.1e' + '0' * (maxdigits+1))

def testImmutable(self):
r = F(7, 3)
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Follow Lee on X/Twitter - Father, Husband, Serial builder creating AI, crypto, games & web tools. We are friends :) AI Will Come To Life!

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