Method check_strtod

Lib/test/test_strtod.py:87–104

Compare the result of Python's builtin correctly rounded string->float conversion (using float) to a pure Python correctly rounded string->float implementation. Fail if the two methods give different results.

(self, s)

class StrtodTests(unittest.TestCase):
    def check_strtod(self, s):
        """Compare the result of Python's builtin correctly rounded
        string->float conversion (using float) to a pure Python
        correctly rounded string->float implementation.  Fail if the
        two methods give different results."""

        try:
            fs = float(s)
        except OverflowError:
            got = '-inf' if s[0] == '-' else 'inf'
        except MemoryError:
            got = 'memory error'
        else:
            got = fs.hex()
        expected = strtod(s)
        self.assertEqual(expected, got,
                         "Incorrectly rounded str->float conversion for {}: "
                         "expected {}, got {}".format(s, expected, got))

    def test_short_halfway_cases(self):
        # exact halfway cases with a small number of significant digits