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import unittest, struct
import os
from test import test_support
def isinf(x):
return x * 0.5 == x
def isnan(x):
return x != x
class FormatFunctionsTestCase(unittest.TestCase):
def setUp(self):
self.save_formats = {'double':float.__getformat__('double'),
'float':float.__getformat__('float')}
def tearDown(self):
float.__setformat__('double', self.save_formats['double'])
float.__setformat__('float', self.save_formats['float'])
def test_getformat(self):
self.assert_(float.__getformat__('double') in
['unknown', 'IEEE, big-endian', 'IEEE, little-endian'])
self.assert_(float.__getformat__('float') in
['unknown', 'IEEE, big-endian', 'IEEE, little-endian'])
self.assertRaises(ValueError, float.__getformat__, 'chicken')
self.assertRaises(TypeError, float.__getformat__, 1)
def test_setformat(self):
for t in 'double', 'float':
float.__setformat__(t, 'unknown')
if self.save_formats[t] == 'IEEE, big-endian':
self.assertRaises(ValueError, float.__setformat__,
t, 'IEEE, little-endian')
elif self.save_formats[t] == 'IEEE, little-endian':
self.assertRaises(ValueError, float.__setformat__,
t, 'IEEE, big-endian')
else:
self.assertRaises(ValueError, float.__setformat__,
t, 'IEEE, big-endian')
self.assertRaises(ValueError, float.__setformat__,
t, 'IEEE, little-endian')
self.assertRaises(ValueError, float.__setformat__,
t, 'chicken')
self.assertRaises(ValueError, float.__setformat__,
'chicken', 'unknown')
BE_DOUBLE_INF = '\x7f\xf0\x00\x00\x00\x00\x00\x00'
LE_DOUBLE_INF = ''.join(reversed(BE_DOUBLE_INF))
BE_DOUBLE_NAN = '\x7f\xf8\x00\x00\x00\x00\x00\x00'
LE_DOUBLE_NAN = ''.join(reversed(BE_DOUBLE_NAN))
BE_FLOAT_INF = '\x7f\x80\x00\x00'
LE_FLOAT_INF = ''.join(reversed(BE_FLOAT_INF))
BE_FLOAT_NAN = '\x7f\xc0\x00\x00'
LE_FLOAT_NAN = ''.join(reversed(BE_FLOAT_NAN))
# on non-IEEE platforms, attempting to unpack a bit pattern
# representing an infinity or a NaN should raise an exception.
class UnknownFormatTestCase(unittest.TestCase):
def setUp(self):
self.save_formats = {'double':float.__getformat__('double'),
'float':float.__getformat__('float')}
float.__setformat__('double', 'unknown')
float.__setformat__('float', 'unknown')
def tearDown(self):
float.__setformat__('double', self.save_formats['double'])
float.__setformat__('float', self.save_formats['float'])
def test_double_specials_dont_unpack(self):
for fmt, data in [('>d', BE_DOUBLE_INF),
('>d', BE_DOUBLE_NAN),
('<d', LE_DOUBLE_INF),
('<d', LE_DOUBLE_NAN)]:
self.assertRaises(ValueError, struct.unpack, fmt, data)
def test_float_specials_dont_unpack(self):
for fmt, data in [('>f', BE_FLOAT_INF),
('>f', BE_FLOAT_NAN),
('<f', LE_FLOAT_INF),
('<f', LE_FLOAT_NAN)]:
self.assertRaises(ValueError, struct.unpack, fmt, data)
# on an IEEE platform, all we guarantee is that bit patterns
# representing infinities or NaNs do not raise an exception; all else
# is accident (today).
# let's also try to guarantee that -0.0 and 0.0 don't get confused.
class IEEEFormatTestCase(unittest.TestCase):
if float.__getformat__("double").startswith("IEEE"):
def test_double_specials_do_unpack(self):
for fmt, data in [('>d', BE_DOUBLE_INF),
('>d', BE_DOUBLE_NAN),
('<d', LE_DOUBLE_INF),
('<d', LE_DOUBLE_NAN)]:
struct.unpack(fmt, data)
if float.__getformat__("float").startswith("IEEE"):
def test_float_specials_do_unpack(self):
for fmt, data in [('>f', BE_FLOAT_INF),
('>f', BE_FLOAT_NAN),
('<f', LE_FLOAT_INF),
('<f', LE_FLOAT_NAN)]:
struct.unpack(fmt, data)
if float.__getformat__("double").startswith("IEEE"):
def test_negative_zero(self):
import math
def pos_pos():
return 0.0, math.atan2(0.0, -1)
def pos_neg():
return 0.0, math.atan2(-0.0, -1)
def neg_pos():
return -0.0, math.atan2(0.0, -1)
def neg_neg():
return -0.0, math.atan2(-0.0, -1)
self.assertEquals(pos_pos(), neg_pos())
self.assertEquals(pos_neg(), neg_neg())
if float.__getformat__("double").startswith("IEEE"):
def test_underflow_sign(self):
import math
# check that -1e-1000 gives -0.0, not 0.0
self.assertEquals(math.atan2(-1e-1000, -1), math.atan2(-0.0, -1))
self.assertEquals(math.atan2(float('-1e-1000'), -1),
math.atan2(-0.0, -1))
class ReprTestCase(unittest.TestCase):
def test_repr(self):
floats_file = open(os.path.join(os.path.split(__file__)[0],
'floating_points.txt'))
for line in floats_file:
line = line.strip()
if not line or line.startswith('#'):
continue
v = eval(line)
self.assertEqual(v, eval(repr(v)))
floats_file.close()
# Beginning with Python 2.6 float has cross platform compatible
# ways to create and representate inf and nan
class InfNanTest(unittest.TestCase):
def test_inf_from_str(self):
self.assert_(isinf(float("inf")))
self.assert_(isinf(float("+inf")))
self.assert_(isinf(float("-inf")))
self.assertEqual(repr(float("inf")), "inf")
self.assertEqual(repr(float("+inf")), "inf")
self.assertEqual(repr(float("-inf")), "-inf")
self.assertEqual(repr(float("INF")), "inf")
self.assertEqual(repr(float("+Inf")), "inf")
self.assertEqual(repr(float("-iNF")), "-inf")
self.assertEqual(str(float("inf")), "inf")
self.assertEqual(str(float("+inf")), "inf")
self.assertEqual(str(float("-inf")), "-inf")
self.assertRaises(ValueError, float, "info")
self.assertRaises(ValueError, float, "+info")
self.assertRaises(ValueError, float, "-info")
self.assertRaises(ValueError, float, "in")
self.assertRaises(ValueError, float, "+in")
self.assertRaises(ValueError, float, "-in")
def test_inf_as_str(self):
self.assertEqual(repr(1e300 * 1e300), "inf")
self.assertEqual(repr(-1e300 * 1e300), "-inf")
self.assertEqual(str(1e300 * 1e300), "inf")
self.assertEqual(str(-1e300 * 1e300), "-inf")
def test_nan_from_str(self):
self.assert_(isnan(float("nan")))
self.assert_(isnan(float("+nan")))
self.assert_(isnan(float("-nan")))
self.assertEqual(repr(float("nan")), "nan")
self.assertEqual(repr(float("+nan")), "nan")
self.assertEqual(repr(float("-nan")), "nan")
self.assertEqual(repr(float("NAN")), "nan")
self.assertEqual(repr(float("+NAn")), "nan")
self.assertEqual(repr(float("-NaN")), "nan")
self.assertEqual(str(float("nan")), "nan")
self.assertEqual(str(float("+nan")), "nan")
self.assertEqual(str(float("-nan")), "nan")
self.assertRaises(ValueError, float, "nana")
self.assertRaises(ValueError, float, "+nana")
self.assertRaises(ValueError, float, "-nana")
self.assertRaises(ValueError, float, "na")
self.assertRaises(ValueError, float, "+na")
self.assertRaises(ValueError, float, "-na")
def test_nan_as_str(self):
self.assertEqual(repr(1e300 * 1e300 * 0), "nan")
self.assertEqual(repr(-1e300 * 1e300 * 0), "nan")
self.assertEqual(str(1e300 * 1e300 * 0), "nan")
self.assertEqual(str(-1e300 * 1e300 * 0), "nan")
def test_main():
test_support.run_unittest(
FormatFunctionsTestCase,
UnknownFormatTestCase,
IEEEFormatTestCase,
ReprTestCase,
InfNanTest,
)
if __name__ == '__main__':
test_main()
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