Method test_hash_method

Lib/test/test_decimal.py:1910–1986

(self)

        self.assertEqual(id(dc), id(d))

    def test_hash_method(self):

        Decimal = self.decimal.Decimal
        localcontext = self.decimal.localcontext

        def hashit(d):
            a = hash(d)
            b = d.__hash__()
            self.assertEqual(a, b)
            return a

        #just that it's hashable
        hashit(Decimal(23))
        hashit(Decimal('Infinity'))
        hashit(Decimal('-Infinity'))
        hashit(Decimal('nan123'))
        hashit(Decimal('-NaN'))

        test_values = [Decimal(sign*(2**m + n))
                       for m in [0, 14, 15, 16, 17, 30, 31,
                                 32, 33, 61, 62, 63, 64, 65, 66]
                       for n in range(-10, 10)
                       for sign in [-1, 1]]
        test_values.extend([
                Decimal("-1"), # ==> -2
                Decimal("-0"), # zeros
                Decimal("0.00"),
                Decimal("-0.000"),
                Decimal("0E10"),
                Decimal("-0E12"),
                Decimal("10.0"), # negative exponent
                Decimal("-23.00000"),
                Decimal("1230E100"), # positive exponent
                Decimal("-4.5678E50"),
                # a value for which hash(n) != hash(n % (2**64-1))
                # in Python pre-2.6
                Decimal(2**64 + 2**32 - 1),
                # selection of values which fail with the old (before
                # version 2.6) long.__hash__
                Decimal("1.634E100"),
                Decimal("90.697E100"),
                Decimal("188.83E100"),
                Decimal("1652.9E100"),
                Decimal("56531E100"),
                ])

        # check that hash(d) == hash(int(d)) for integral values
        for value in test_values:
            self.assertEqual(hashit(value), hash(int(value)))

        # check that the hashes of a Decimal float match when they
        # represent exactly the same values
        test_strings = ['inf', '-Inf', '0.0', '-.0e1',
                        '34.0', '2.5', '112390.625', '-0.515625']
        for s in test_strings:
            f = float(s)
            d = Decimal(s)
            self.assertEqual(hashit(d), hash(f))