Method test_halfway_cases

Lib/test/test_strtod.py:149–173

(self)

                    exponent -= 1

    def test_halfway_cases(self):
        # test halfway cases for the round-half-to-even rule
        for i in range(100 * TEST_SIZE):
            # bit pattern for a random finite positive (or +0.0) float
            bits = random.randrange(2047*2**52)

            # convert bit pattern to a number of the form m * 2**e
            e, m = divmod(bits, 2**52)
            if e:
                m, e = m + 2**52, e - 1
            e -= 1074

            # add 0.5 ulps
            m, e = 2*m + 1, e - 1

            # convert to a decimal string
            if e >= 0:
                digits = m << e
                exponent = 0
            else:
                # m * 2**e = (m * 5**-e) * 10**e
                digits = m * 5**-e
                exponent = e
            s = '{}e{}'.format(digits, exponent)
            self.check_strtod(s)

    def test_boundaries(self):
        # boundaries expressed as triples (n, e, u), where