Thanks to visit codestin.com
Credit goes to github.com

Skip to content

Improve tests for str to Fraction conversion #134010

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
May 14, 2025
Merged

Improve tests for str to Fraction conversion #134010

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
207 changes: 97 additions & 110 deletions Lib/test/test_fractions.py
View file
Open in desktop
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
Expand Down Expand Up @@ -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 ")))
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Why this was replaced, not added?

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It is virtually the same test, but tests that more than one zero is accepted. There were no tests for leading zero in other forms, so they were added.

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 ")))
Expand All @@ -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)
Comment on lines +425 to +427
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This looks fine.

But maybe use subTest?

for value in ["3/", "/2",  # there can be a lot of...
              # Denominators don't need a sign.
              "3/+2", "3/-2",
              # Imitate float's parsing.
              ...]:
    with self.subTest(value=value):
        check_invalid(value)

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The main reason is that if we make error messages more specific, it is easier to add an optional parameter, while keeping default for most tests. For example, I originally planned to add the tests here that are currently in test_limit_int.


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)
Expand Down
Loading