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# test interactions betwen int, float, Decimal and Fraction
import unittest
import random
import math
import sys
import operator
from test.support import run_unittest
from decimal import Decimal as D
from fractions import Fraction as F
# Constants related to the hash implementation; hash(x) is based
# on the reduction of x modulo the prime _PyHASH_MODULUS.
_PyHASH_MODULUS = sys.hash_info.modulus
_PyHASH_INF = sys.hash_info.inf
class HashTest(unittest.TestCase):
def check_equal_hash(self, x, y):
# check both that x and y are equal and that their hashes are equal
self.assertEqual(hash(x), hash(y),
"got different hashes for {!r} and {!r}".format(x, y))
self.assertEqual(x, y)
def test_bools(self):
self.check_equal_hash(False, 0)
self.check_equal_hash(True, 1)
def test_integers(self):
# check that equal values hash equal
# exact integers
for i in range(-1000, 1000):
self.check_equal_hash(i, float(i))
self.check_equal_hash(i, D(i))
self.check_equal_hash(i, F(i))
# the current hash is based on reduction modulo 2**n-1 for some
# n, so pay special attention to numbers of the form 2**n and 2**n-1.
for i in range(100):
n = 2**i - 1
if n == int(float(n)):
self.check_equal_hash(n, float(n))
self.check_equal_hash(-n, -float(n))
self.check_equal_hash(n, D(n))
self.check_equal_hash(n, F(n))
self.check_equal_hash(-n, D(-n))
self.check_equal_hash(-n, F(-n))
n = 2**i
self.check_equal_hash(n, float(n))
self.check_equal_hash(-n, -float(n))
self.check_equal_hash(n, D(n))
self.check_equal_hash(n, F(n))
self.check_equal_hash(-n, D(-n))
self.check_equal_hash(-n, F(-n))
# random values of various sizes
for _ in range(1000):
e = random.randrange(300)
n = random.randrange(-10**e, 10**e)
self.check_equal_hash(n, D(n))
self.check_equal_hash(n, F(n))
if n == int(float(n)):
self.check_equal_hash(n, float(n))
def test_binary_floats(self):
# check that floats hash equal to corresponding Fractions and Decimals
# floats that are distinct but numerically equal should hash the same
self.check_equal_hash(0.0, -0.0)
# zeros
self.check_equal_hash(0.0, D(0))
self.check_equal_hash(-0.0, D(0))
self.check_equal_hash(-0.0, D('-0.0'))
self.check_equal_hash(0.0, F(0))
# infinities and nans
self.check_equal_hash(float('inf'), D('inf'))
self.check_equal_hash(float('-inf'), D('-inf'))
for _ in range(1000):
x = random.random() * math.exp(random.random()*200.0 - 100.0)
self.check_equal_hash(x, D.from_float(x))
self.check_equal_hash(x, F.from_float(x))
def test_complex(self):
# complex numbers with zero imaginary part should hash equal to
# the corresponding float
test_values = [0.0, -0.0, 1.0, -1.0, 0.40625, -5136.5,
float('inf'), float('-inf')]
for zero in -0.0, 0.0:
for value in test_values:
self.check_equal_hash(value, complex(value, zero))
def test_decimals(self):
# check that Decimal instances that have different representations
# but equal values give the same hash
zeros = ['0', '-0', '0.0', '-0.0e10', '000e-10']
for zero in zeros:
self.check_equal_hash(D(zero), D(0))
self.check_equal_hash(D('1.00'), D(1))
self.check_equal_hash(D('1.00000'), D(1))
self.check_equal_hash(D('-1.00'), D(-1))
self.check_equal_hash(D('-1.00000'), D(-1))
self.check_equal_hash(D('123e2'), D(12300))
self.check_equal_hash(D('1230e1'), D(12300))
self.check_equal_hash(D('12300'), D(12300))
self.check_equal_hash(D('12300.0'), D(12300))
self.check_equal_hash(D('12300.00'), D(12300))
self.check_equal_hash(D('12300.000'), D(12300))
def test_fractions(self):
# check special case for fractions where either the numerator
# or the denominator is a multiple of _PyHASH_MODULUS
self.assertEqual(hash(F(1, _PyHASH_MODULUS)), _PyHASH_INF)
self.assertEqual(hash(F(-1, 3*_PyHASH_MODULUS)), -_PyHASH_INF)
self.assertEqual(hash(F(7*_PyHASH_MODULUS, 1)), 0)
self.assertEqual(hash(F(-_PyHASH_MODULUS, 1)), 0)
def test_hash_normalization(self):
# Test for a bug encountered while changing long_hash.
#
# Given objects x and y, it should be possible for y's
# __hash__ method to return hash(x) in order to ensure that
# hash(x) == hash(y). But hash(x) is not exactly equal to the
# result of x.__hash__(): there's some internal normalization
# to make sure that the result fits in a C long, and is not
# equal to the invalid hash value -1. This internal
# normalization must therefore not change the result of
# hash(x) for any x.
class HalibutProxy:
def __hash__(self):
return hash('halibut')
def __eq__(self, other):
return other == 'halibut'
x = {'halibut', HalibutProxy()}
self.assertEqual(len(x), 1)
def test_main():
run_unittest(HashTest)
if __name__ == '__main__':
test_main()
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