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97c1adf393
- Issue #25958: Support "anti-registration" of special methods from various ABCs, like __hash__, __iter__ or __len__. All these (and several more) can be set to None in an implementation class and the behavior will be as if the method is not defined at all. (Previously, this mechanism existed only for __hash__, to make mutable classes unhashable.) Code contributed by Andrew Barnert and Ivan Levkivskyi.
441 lines
14 KiB
Python
441 lines
14 KiB
Python
"""Tests for binary operators on subtypes of built-in types."""
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import unittest
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from test import support
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from operator import eq, le, ne
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from abc import ABCMeta
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def gcd(a, b):
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"""Greatest common divisor using Euclid's algorithm."""
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while a:
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a, b = b%a, a
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return b
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def isint(x):
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"""Test whether an object is an instance of int."""
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return isinstance(x, int)
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def isnum(x):
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"""Test whether an object is an instance of a built-in numeric type."""
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for T in int, float, complex:
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if isinstance(x, T):
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return 1
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return 0
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def isRat(x):
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"""Test wheter an object is an instance of the Rat class."""
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return isinstance(x, Rat)
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class Rat(object):
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"""Rational number implemented as a normalized pair of ints."""
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__slots__ = ['_Rat__num', '_Rat__den']
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def __init__(self, num=0, den=1):
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"""Constructor: Rat([num[, den]]).
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The arguments must be ints, and default to (0, 1)."""
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if not isint(num):
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raise TypeError("Rat numerator must be int (%r)" % num)
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if not isint(den):
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raise TypeError("Rat denominator must be int (%r)" % den)
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# But the zero is always on
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if den == 0:
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raise ZeroDivisionError("zero denominator")
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g = gcd(den, num)
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self.__num = int(num//g)
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self.__den = int(den//g)
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def _get_num(self):
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"""Accessor function for read-only 'num' attribute of Rat."""
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return self.__num
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num = property(_get_num, None)
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def _get_den(self):
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"""Accessor function for read-only 'den' attribute of Rat."""
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return self.__den
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den = property(_get_den, None)
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def __repr__(self):
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"""Convert a Rat to a string resembling a Rat constructor call."""
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return "Rat(%d, %d)" % (self.__num, self.__den)
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def __str__(self):
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"""Convert a Rat to a string resembling a decimal numeric value."""
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return str(float(self))
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def __float__(self):
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"""Convert a Rat to a float."""
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return self.__num*1.0/self.__den
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def __int__(self):
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"""Convert a Rat to an int; self.den must be 1."""
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if self.__den == 1:
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try:
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return int(self.__num)
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except OverflowError:
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raise OverflowError("%s too large to convert to int" %
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repr(self))
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raise ValueError("can't convert %s to int" % repr(self))
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def __add__(self, other):
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"""Add two Rats, or a Rat and a number."""
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if isint(other):
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other = Rat(other)
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if isRat(other):
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return Rat(self.__num*other.__den + other.__num*self.__den,
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self.__den*other.__den)
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if isnum(other):
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return float(self) + other
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return NotImplemented
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__radd__ = __add__
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def __sub__(self, other):
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"""Subtract two Rats, or a Rat and a number."""
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if isint(other):
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other = Rat(other)
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if isRat(other):
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return Rat(self.__num*other.__den - other.__num*self.__den,
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self.__den*other.__den)
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if isnum(other):
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return float(self) - other
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return NotImplemented
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def __rsub__(self, other):
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"""Subtract two Rats, or a Rat and a number (reversed args)."""
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if isint(other):
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other = Rat(other)
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if isRat(other):
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return Rat(other.__num*self.__den - self.__num*other.__den,
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self.__den*other.__den)
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if isnum(other):
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return other - float(self)
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return NotImplemented
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def __mul__(self, other):
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"""Multiply two Rats, or a Rat and a number."""
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if isRat(other):
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return Rat(self.__num*other.__num, self.__den*other.__den)
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if isint(other):
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return Rat(self.__num*other, self.__den)
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if isnum(other):
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return float(self)*other
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return NotImplemented
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__rmul__ = __mul__
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def __truediv__(self, other):
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"""Divide two Rats, or a Rat and a number."""
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if isRat(other):
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return Rat(self.__num*other.__den, self.__den*other.__num)
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if isint(other):
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return Rat(self.__num, self.__den*other)
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if isnum(other):
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return float(self) / other
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return NotImplemented
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def __rtruediv__(self, other):
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"""Divide two Rats, or a Rat and a number (reversed args)."""
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if isRat(other):
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return Rat(other.__num*self.__den, other.__den*self.__num)
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if isint(other):
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return Rat(other*self.__den, self.__num)
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if isnum(other):
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return other / float(self)
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return NotImplemented
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def __floordiv__(self, other):
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"""Divide two Rats, returning the floored result."""
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if isint(other):
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other = Rat(other)
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elif not isRat(other):
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return NotImplemented
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x = self/other
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return x.__num // x.__den
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def __rfloordiv__(self, other):
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"""Divide two Rats, returning the floored result (reversed args)."""
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x = other/self
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return x.__num // x.__den
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def __divmod__(self, other):
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"""Divide two Rats, returning quotient and remainder."""
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if isint(other):
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other = Rat(other)
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elif not isRat(other):
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return NotImplemented
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x = self//other
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return (x, self - other * x)
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def __rdivmod__(self, other):
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"""Divide two Rats, returning quotient and remainder (reversed args)."""
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if isint(other):
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other = Rat(other)
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elif not isRat(other):
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return NotImplemented
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return divmod(other, self)
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def __mod__(self, other):
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"""Take one Rat modulo another."""
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return divmod(self, other)[1]
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def __rmod__(self, other):
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"""Take one Rat modulo another (reversed args)."""
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return divmod(other, self)[1]
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def __eq__(self, other):
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"""Compare two Rats for equality."""
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if isint(other):
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return self.__den == 1 and self.__num == other
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if isRat(other):
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return self.__num == other.__num and self.__den == other.__den
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if isnum(other):
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return float(self) == other
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return NotImplemented
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class RatTestCase(unittest.TestCase):
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"""Unit tests for Rat class and its support utilities."""
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def test_gcd(self):
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self.assertEqual(gcd(10, 12), 2)
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self.assertEqual(gcd(10, 15), 5)
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self.assertEqual(gcd(10, 11), 1)
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self.assertEqual(gcd(100, 15), 5)
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self.assertEqual(gcd(-10, 2), -2)
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self.assertEqual(gcd(10, -2), 2)
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self.assertEqual(gcd(-10, -2), -2)
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for i in range(1, 20):
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for j in range(1, 20):
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self.assertTrue(gcd(i, j) > 0)
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self.assertTrue(gcd(-i, j) < 0)
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self.assertTrue(gcd(i, -j) > 0)
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self.assertTrue(gcd(-i, -j) < 0)
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def test_constructor(self):
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a = Rat(10, 15)
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self.assertEqual(a.num, 2)
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self.assertEqual(a.den, 3)
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a = Rat(10, -15)
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self.assertEqual(a.num, -2)
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self.assertEqual(a.den, 3)
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a = Rat(-10, 15)
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self.assertEqual(a.num, -2)
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self.assertEqual(a.den, 3)
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a = Rat(-10, -15)
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self.assertEqual(a.num, 2)
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self.assertEqual(a.den, 3)
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a = Rat(7)
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self.assertEqual(a.num, 7)
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self.assertEqual(a.den, 1)
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try:
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a = Rat(1, 0)
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except ZeroDivisionError:
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pass
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else:
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self.fail("Rat(1, 0) didn't raise ZeroDivisionError")
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for bad in "0", 0.0, 0j, (), [], {}, None, Rat, unittest:
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try:
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a = Rat(bad)
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except TypeError:
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pass
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else:
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self.fail("Rat(%r) didn't raise TypeError" % bad)
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try:
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a = Rat(1, bad)
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except TypeError:
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pass
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else:
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self.fail("Rat(1, %r) didn't raise TypeError" % bad)
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def test_add(self):
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self.assertEqual(Rat(2, 3) + Rat(1, 3), 1)
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self.assertEqual(Rat(2, 3) + 1, Rat(5, 3))
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self.assertEqual(1 + Rat(2, 3), Rat(5, 3))
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self.assertEqual(1.0 + Rat(1, 2), 1.5)
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self.assertEqual(Rat(1, 2) + 1.0, 1.5)
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def test_sub(self):
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self.assertEqual(Rat(7, 2) - Rat(7, 5), Rat(21, 10))
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self.assertEqual(Rat(7, 5) - 1, Rat(2, 5))
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self.assertEqual(1 - Rat(3, 5), Rat(2, 5))
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self.assertEqual(Rat(3, 2) - 1.0, 0.5)
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self.assertEqual(1.0 - Rat(1, 2), 0.5)
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def test_mul(self):
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self.assertEqual(Rat(2, 3) * Rat(5, 7), Rat(10, 21))
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self.assertEqual(Rat(10, 3) * 3, 10)
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self.assertEqual(3 * Rat(10, 3), 10)
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self.assertEqual(Rat(10, 5) * 0.5, 1.0)
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self.assertEqual(0.5 * Rat(10, 5), 1.0)
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def test_div(self):
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self.assertEqual(Rat(10, 3) / Rat(5, 7), Rat(14, 3))
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self.assertEqual(Rat(10, 3) / 3, Rat(10, 9))
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self.assertEqual(2 / Rat(5), Rat(2, 5))
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self.assertEqual(3.0 * Rat(1, 2), 1.5)
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self.assertEqual(Rat(1, 2) * 3.0, 1.5)
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def test_floordiv(self):
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self.assertEqual(Rat(10) // Rat(4), 2)
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self.assertEqual(Rat(10, 3) // Rat(4, 3), 2)
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self.assertEqual(Rat(10) // 4, 2)
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self.assertEqual(10 // Rat(4), 2)
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def test_eq(self):
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self.assertEqual(Rat(10), Rat(20, 2))
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self.assertEqual(Rat(10), 10)
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self.assertEqual(10, Rat(10))
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self.assertEqual(Rat(10), 10.0)
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self.assertEqual(10.0, Rat(10))
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def test_true_div(self):
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self.assertEqual(Rat(10, 3) / Rat(5, 7), Rat(14, 3))
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self.assertEqual(Rat(10, 3) / 3, Rat(10, 9))
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self.assertEqual(2 / Rat(5), Rat(2, 5))
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self.assertEqual(3.0 * Rat(1, 2), 1.5)
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self.assertEqual(Rat(1, 2) * 3.0, 1.5)
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self.assertEqual(eval('1/2'), 0.5)
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# XXX Ran out of steam; TO DO: divmod, div, future division
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class OperationLogger:
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"""Base class for classes with operation logging."""
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def __init__(self, logger):
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self.logger = logger
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def log_operation(self, *args):
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self.logger(*args)
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def op_sequence(op, *classes):
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"""Return the sequence of operations that results from applying
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the operation `op` to instances of the given classes."""
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log = []
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instances = []
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for c in classes:
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instances.append(c(log.append))
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try:
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op(*instances)
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except TypeError:
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pass
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return log
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class A(OperationLogger):
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def __eq__(self, other):
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self.log_operation('A.__eq__')
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return NotImplemented
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def __le__(self, other):
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self.log_operation('A.__le__')
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return NotImplemented
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def __ge__(self, other):
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self.log_operation('A.__ge__')
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return NotImplemented
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class B(OperationLogger, metaclass=ABCMeta):
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def __eq__(self, other):
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self.log_operation('B.__eq__')
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return NotImplemented
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def __le__(self, other):
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self.log_operation('B.__le__')
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return NotImplemented
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def __ge__(self, other):
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self.log_operation('B.__ge__')
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return NotImplemented
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class C(B):
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def __eq__(self, other):
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self.log_operation('C.__eq__')
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return NotImplemented
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def __le__(self, other):
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self.log_operation('C.__le__')
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return NotImplemented
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def __ge__(self, other):
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self.log_operation('C.__ge__')
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return NotImplemented
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class V(OperationLogger):
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"""Virtual subclass of B"""
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def __eq__(self, other):
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self.log_operation('V.__eq__')
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return NotImplemented
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def __le__(self, other):
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self.log_operation('V.__le__')
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return NotImplemented
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def __ge__(self, other):
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self.log_operation('V.__ge__')
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return NotImplemented
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B.register(V)
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class OperationOrderTests(unittest.TestCase):
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def test_comparison_orders(self):
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self.assertEqual(op_sequence(eq, A, A), ['A.__eq__', 'A.__eq__'])
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self.assertEqual(op_sequence(eq, A, B), ['A.__eq__', 'B.__eq__'])
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self.assertEqual(op_sequence(eq, B, A), ['B.__eq__', 'A.__eq__'])
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# C is a subclass of B, so C.__eq__ is called first
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self.assertEqual(op_sequence(eq, B, C), ['C.__eq__', 'B.__eq__'])
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self.assertEqual(op_sequence(eq, C, B), ['C.__eq__', 'B.__eq__'])
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self.assertEqual(op_sequence(le, A, A), ['A.__le__', 'A.__ge__'])
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self.assertEqual(op_sequence(le, A, B), ['A.__le__', 'B.__ge__'])
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self.assertEqual(op_sequence(le, B, A), ['B.__le__', 'A.__ge__'])
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self.assertEqual(op_sequence(le, B, C), ['C.__ge__', 'B.__le__'])
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self.assertEqual(op_sequence(le, C, B), ['C.__le__', 'B.__ge__'])
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self.assertTrue(issubclass(V, B))
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self.assertEqual(op_sequence(eq, B, V), ['B.__eq__', 'V.__eq__'])
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self.assertEqual(op_sequence(le, B, V), ['B.__le__', 'V.__ge__'])
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class SupEq(object):
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"""Class that can test equality"""
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def __eq__(self, other):
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return True
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class S(SupEq):
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"""Subclass of SupEq that should fail"""
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__eq__ = None
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class F(object):
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"""Independent class that should fall back"""
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class X(object):
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"""Independent class that should fail"""
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__eq__ = None
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class SN(SupEq):
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"""Subclass of SupEq that can test equality, but not non-equality"""
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__ne__ = None
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class XN:
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"""Independent class that can test equality, but not non-equality"""
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def __eq__(self, other):
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return True
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__ne__ = None
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class FallbackBlockingTests(unittest.TestCase):
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"""Unit tests for None method blocking"""
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def test_fallback_rmethod_blocking(self):
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e, f, s, x = SupEq(), F(), S(), X()
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self.assertEqual(e, e)
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self.assertEqual(e, f)
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self.assertEqual(f, e)
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# left operand is checked first
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self.assertEqual(e, x)
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self.assertRaises(TypeError, eq, x, e)
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# S is a subclass, so it's always checked first
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self.assertRaises(TypeError, eq, e, s)
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self.assertRaises(TypeError, eq, s, e)
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def test_fallback_ne_blocking(self):
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e, sn, xn = SupEq(), SN(), XN()
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self.assertFalse(e != e)
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self.assertRaises(TypeError, ne, e, sn)
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self.assertRaises(TypeError, ne, sn, e)
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self.assertFalse(e != xn)
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self.assertRaises(TypeError, ne, xn, e)
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if __name__ == "__main__":
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unittest.main()
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