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cpython/Lib/test/test_long.py
Armin Rigo 7ccbca93a2 Forward-port of r52136,52138: a review of overflow-detecting code. 
* unified the way intobject, longobject and mystrtoul handle
  values around -sys.maxint-1.

* in general, trying to entierely avoid overflows in any computation
  involving signed ints or longs is extremely involved.  Fixed a few
  simple cases where a compiler might be too clever (but that's all
  guesswork).

* more overflow checks against bad data in marshal.c.

* 2.5 specific: fixed a number of places that were still confusing int
  and Py_ssize_t.  Some of them could potentially have caused
  "real-world" breakage.

* list.pop(x): fixing overflow issues on x was messy.  I just reverted
  to PyArg_ParseTuple("n"), which does the right thing.  (An obscure
  test was trying to give a Decimal to list.pop()... doesn't make
  sense any more IMHO)

* trying to write a few tests...
2006-10-04 12:17:45 +00:00

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import unittest
from test import test_support
import random
# Used for lazy formatting of failure messages
class Frm(object):
def __init__(self, format, *args):
self.format = format
self.args = args
def __str__(self):
return self.format % self.args
# SHIFT should match the value in longintrepr.h for best testing.
SHIFT = 15
BASE = 2 ** SHIFT
MASK = BASE - 1
KARATSUBA_CUTOFF = 70 # from longobject.c
# Max number of base BASE digits to use in test cases. Doubling
# this will more than double the runtime.
MAXDIGITS = 15
# build some special values
special = map(long, [0, 1, 2, BASE, BASE >> 1])
special.append(0x5555555555555555L)
special.append(0xaaaaaaaaaaaaaaaaL)
# some solid strings of one bits
p2 = 4L # 0 and 1 already added
for i in range(2*SHIFT):
special.append(p2 - 1)
p2 = p2 << 1
del p2
# add complements & negations
special = special + map(lambda x: ~x, special) + \
map(lambda x: -x, special)
class LongTest(unittest.TestCase):
# Get quasi-random long consisting of ndigits digits (in base BASE).
# quasi == the most-significant digit will not be 0, and the number
# is constructed to contain long strings of 0 and 1 bits. These are
# more likely than random bits to provoke digit-boundary errors.
# The sign of the number is also random.
def getran(self, ndigits):
self.assert_(ndigits > 0)
nbits_hi = ndigits * SHIFT
nbits_lo = nbits_hi - SHIFT + 1
answer = 0L
nbits = 0
r = int(random.random() * (SHIFT * 2)) | 1 # force 1 bits to start
while nbits < nbits_lo:
bits = (r >> 1) + 1
bits = min(bits, nbits_hi - nbits)
self.assert_(1 <= bits <= SHIFT)
nbits = nbits + bits
answer = answer << bits
if r & 1:
answer = answer | ((1 << bits) - 1)
r = int(random.random() * (SHIFT * 2))
self.assert_(nbits_lo <= nbits <= nbits_hi)
if random.random() < 0.5:
answer = -answer
return answer
# Get random long consisting of ndigits random digits (relative to base
# BASE). The sign bit is also random.
def getran2(ndigits):
answer = 0L
for i in xrange(ndigits):
answer = (answer << SHIFT) | random.randint(0, MASK)
if random.random() < 0.5:
answer = -answer
return answer
def check_division(self, x, y):
eq = self.assertEqual
q, r = divmod(x, y)
q2, r2 = x//y, x%y
pab, pba = x*y, y*x
eq(pab, pba, Frm("multiplication does not commute for %r and %r", x, y))
eq(q, q2, Frm("divmod returns different quotient than / for %r and %r", x, y))
eq(r, r2, Frm("divmod returns different mod than %% for %r and %r", x, y))
eq(x, q*y + r, Frm("x != q*y + r after divmod on x=%r, y=%r", x, y))
if y > 0:
self.assert_(0 <= r < y, Frm("bad mod from divmod on %r and %r", x, y))
else:
self.assert_(y < r <= 0, Frm("bad mod from divmod on %r and %r", x, y))
def test_division(self):
digits = range(1, MAXDIGITS+1) + range(KARATSUBA_CUTOFF,
KARATSUBA_CUTOFF + 14)
digits.append(KARATSUBA_CUTOFF * 3)
for lenx in digits:
x = self.getran(lenx)
for leny in digits:
y = self.getran(leny) or 1L
self.check_division(x, y)
def test_karatsuba(self):
digits = range(1, 5) + range(KARATSUBA_CUTOFF, KARATSUBA_CUTOFF + 10)
digits.extend([KARATSUBA_CUTOFF * 10, KARATSUBA_CUTOFF * 100])
bits = [digit * SHIFT for digit in digits]
# Test products of long strings of 1 bits -- (2**x-1)*(2**y-1) ==
# 2**(x+y) - 2**x - 2**y + 1, so the proper result is easy to check.
for abits in bits:
a = (1L << abits) - 1
for bbits in bits:
if bbits < abits:
continue
b = (1L << bbits) - 1
x = a * b
y = ((1L << (abits + bbits)) -
(1L << abits) -
(1L << bbits) +
1)
self.assertEqual(x, y,
Frm("bad result for a*b: a=%r, b=%r, x=%r, y=%r", a, b, x, y))
def check_bitop_identities_1(self, x):
eq = self.assertEqual
eq(x & 0, 0, Frm("x & 0 != 0 for x=%r", x))
eq(x | 0, x, Frm("x | 0 != x for x=%r", x))
eq(x ^ 0, x, Frm("x ^ 0 != x for x=%r", x))
eq(x & -1, x, Frm("x & -1 != x for x=%r", x))
eq(x | -1, -1, Frm("x | -1 != -1 for x=%r", x))
eq(x ^ -1, ~x, Frm("x ^ -1 != ~x for x=%r", x))
eq(x, ~~x, Frm("x != ~~x for x=%r", x))
eq(x & x, x, Frm("x & x != x for x=%r", x))
eq(x | x, x, Frm("x | x != x for x=%r", x))
eq(x ^ x, 0, Frm("x ^ x != 0 for x=%r", x))
eq(x & ~x, 0, Frm("x & ~x != 0 for x=%r", x))
eq(x | ~x, -1, Frm("x | ~x != -1 for x=%r", x))
eq(x ^ ~x, -1, Frm("x ^ ~x != -1 for x=%r", x))
eq(-x, 1 + ~x, Frm("not -x == 1 + ~x for x=%r", x))
eq(-x, ~(x-1), Frm("not -x == ~(x-1) forx =%r", x))
for n in xrange(2*SHIFT):
p2 = 2L ** n
eq(x << n >> n, x,
Frm("x << n >> n != x for x=%r, n=%r", (x, n)))
eq(x // p2, x >> n,
Frm("x // p2 != x >> n for x=%r n=%r p2=%r", (x, n, p2)))
eq(x * p2, x << n,
Frm("x * p2 != x << n for x=%r n=%r p2=%r", (x, n, p2)))
eq(x & -p2, x >> n << n,
Frm("not x & -p2 == x >> n << n for x=%r n=%r p2=%r", (x, n, p2)))
eq(x & -p2, x & ~(p2 - 1),
Frm("not x & -p2 == x & ~(p2 - 1) for x=%r n=%r p2=%r", (x, n, p2)))
def check_bitop_identities_2(self, x, y):
eq = self.assertEqual
eq(x & y, y & x, Frm("x & y != y & x for x=%r, y=%r", (x, y)))
eq(x | y, y | x, Frm("x | y != y | x for x=%r, y=%r", (x, y)))
eq(x ^ y, y ^ x, Frm("x ^ y != y ^ x for x=%r, y=%r", (x, y)))
eq(x ^ y ^ x, y, Frm("x ^ y ^ x != y for x=%r, y=%r", (x, y)))
eq(x & y, ~(~x | ~y), Frm("x & y != ~(~x | ~y) for x=%r, y=%r", (x, y)))
eq(x | y, ~(~x & ~y), Frm("x | y != ~(~x & ~y) for x=%r, y=%r", (x, y)))
eq(x ^ y, (x | y) & ~(x & y),
Frm("x ^ y != (x | y) & ~(x & y) for x=%r, y=%r", (x, y)))
eq(x ^ y, (x & ~y) | (~x & y),
Frm("x ^ y == (x & ~y) | (~x & y) for x=%r, y=%r", (x, y)))
eq(x ^ y, (x | y) & (~x | ~y),
Frm("x ^ y == (x | y) & (~x | ~y) for x=%r, y=%r", (x, y)))
def check_bitop_identities_3(self, x, y, z):
eq = self.assertEqual
eq((x & y) & z, x & (y & z),
Frm("(x & y) & z != x & (y & z) for x=%r, y=%r, z=%r", (x, y, z)))
eq((x | y) | z, x | (y | z),
Frm("(x | y) | z != x | (y | z) for x=%r, y=%r, z=%r", (x, y, z)))
eq((x ^ y) ^ z, x ^ (y ^ z),
Frm("(x ^ y) ^ z != x ^ (y ^ z) for x=%r, y=%r, z=%r", (x, y, z)))
eq(x & (y | z), (x & y) | (x & z),
Frm("x & (y | z) != (x & y) | (x & z) for x=%r, y=%r, z=%r", (x, y, z)))
eq(x | (y & z), (x | y) & (x | z),
Frm("x | (y & z) != (x | y) & (x | z) for x=%r, y=%r, z=%r", (x, y, z)))
def test_bitop_identities(self):
for x in special:
self.check_bitop_identities_1(x)
digits = xrange(1, MAXDIGITS+1)
for lenx in digits:
x = self.getran(lenx)
self.check_bitop_identities_1(x)
for leny in digits:
y = self.getran(leny)
self.check_bitop_identities_2(x, y)
self.check_bitop_identities_3(x, y, self.getran((lenx + leny)//2))
def slow_format(self, x, base):
if (x, base) == (0, 8):
# this is an oddball!
return "0L"
digits = []
sign = 0
if x < 0:
sign, x = 1, -x
while x:
x, r = divmod(x, base)
digits.append(int(r))
digits.reverse()
digits = digits or [0]
return '-'[:sign] + \
{8: '0', 10: '', 16: '0x'}[base] + \
"".join(map(lambda i: "0123456789abcdef"[i], digits)) + "L"
def check_format_1(self, x):
for base, mapper in (8, oct), (10, repr), (16, hex):
got = mapper(x)
expected = self.slow_format(x, base)
msg = Frm("%s returned %r but expected %r for %r",
mapper.__name__, got, expected, x)
self.assertEqual(got, expected, msg)
self.assertEqual(long(got, 0), x, Frm('long("%s", 0) != %r', got, x))
# str() has to be checked a little differently since there's no
# trailing "L"
got = str(x)
expected = self.slow_format(x, 10)[:-1]
msg = Frm("%s returned %r but expected %r for %r",
mapper.__name__, got, expected, x)
self.assertEqual(got, expected, msg)
def test_format(self):
for x in special:
self.check_format_1(x)
for i in xrange(10):
for lenx in xrange(1, MAXDIGITS+1):
x = self.getran(lenx)
self.check_format_1(x)
def test_misc(self):
import sys
# check the extremes in int<->long conversion
hugepos = sys.maxint
hugeneg = -hugepos - 1
hugepos_aslong = long(hugepos)
hugeneg_aslong = long(hugeneg)
self.assertEqual(hugepos, hugepos_aslong, "long(sys.maxint) != sys.maxint")
self.assertEqual(hugeneg, hugeneg_aslong,
"long(-sys.maxint-1) != -sys.maxint-1")
# long -> int should not fail for hugepos_aslong or hugeneg_aslong
x = int(hugepos_aslong)
try:
self.assertEqual(x, hugepos,
"converting sys.maxint to long and back to int fails")
except OverflowError:
self.fail("int(long(sys.maxint)) overflowed!")
if not isinstance(x, int):
raise TestFailed("int(long(sys.maxint)) should have returned int")
x = int(hugeneg_aslong)
try:
self.assertEqual(x, hugeneg,
"converting -sys.maxint-1 to long and back to int fails")
except OverflowError:
self.fail("int(long(-sys.maxint-1)) overflowed!")
if not isinstance(x, int):
raise TestFailed("int(long(-sys.maxint-1)) should have "
"returned int")
# but long -> int should overflow for hugepos+1 and hugeneg-1
x = hugepos_aslong + 1
try:
y = int(x)
except OverflowError:
self.fail("int(long(sys.maxint) + 1) mustn't overflow")
self.assert_(isinstance(y, long),
"int(long(sys.maxint) + 1) should have returned long")
x = hugeneg_aslong - 1
try:
y = int(x)
except OverflowError:
self.fail("int(long(-sys.maxint-1) - 1) mustn't overflow")
self.assert_(isinstance(y, long),
"int(long(-sys.maxint-1) - 1) should have returned long")
class long2(long):
pass
x = long2(1L<<100)
y = int(x)
self.assert_(type(y) is long,
"overflowing int conversion must return long not long subtype")
# long -> Py_ssize_t conversion
class X(object):
def __getslice__(self, i, j):
return i, j
self.assertEqual(X()[-5L:7L], (-5, 7))
# use the clamping effect to test the smallest and largest longs
# that fit a Py_ssize_t
slicemin, slicemax = X()[-2L**100:2L**100]
self.assertEqual(X()[slicemin:slicemax], (slicemin, slicemax))
# ----------------------------------- tests of auto int->long conversion
def test_auto_overflow(self):
import math, sys
special = [0, 1, 2, 3, sys.maxint-1, sys.maxint, sys.maxint+1]
sqrt = int(math.sqrt(sys.maxint))
special.extend([sqrt-1, sqrt, sqrt+1])
special.extend([-i for i in special])
def checkit(*args):
# Heavy use of nested scopes here!
self.assertEqual(got, expected,
Frm("for %r expected %r got %r", args, expected, got))
for x in special:
longx = long(x)
expected = -longx
got = -x
checkit('-', x)
for y in special:
longy = long(y)
expected = longx + longy
got = x + y
checkit(x, '+', y)
expected = longx - longy
got = x - y
checkit(x, '-', y)
expected = longx * longy
got = x * y
checkit(x, '*', y)
if y:
expected = longx / longy
got = x / y
checkit(x, '/', y)
expected = longx // longy
got = x // y
checkit(x, '//', y)
expected = divmod(longx, longy)
got = divmod(longx, longy)
checkit(x, 'divmod', y)
if abs(y) < 5 and not (x == 0 and y < 0):
expected = longx ** longy
got = x ** y
checkit(x, '**', y)
for z in special:
if z != 0 :
if y >= 0:
expected = pow(longx, longy, long(z))
got = pow(x, y, z)
checkit('pow', x, y, '%', z)
else:
self.assertRaises(TypeError, pow,longx, longy, long(z))
def test_float_overflow(self):
import math
for x in -2.0, -1.0, 0.0, 1.0, 2.0:
self.assertEqual(float(long(x)), x)
shuge = '12345' * 120
huge = 1L << 30000
mhuge = -huge
namespace = {'huge': huge, 'mhuge': mhuge, 'shuge': shuge, 'math': math}
for test in ["float(huge)", "float(mhuge)",
"complex(huge)", "complex(mhuge)",
"complex(huge, 1)", "complex(mhuge, 1)",
"complex(1, huge)", "complex(1, mhuge)",
"1. + huge", "huge + 1.", "1. + mhuge", "mhuge + 1.",
"1. - huge", "huge - 1.", "1. - mhuge", "mhuge - 1.",
"1. * huge", "huge * 1.", "1. * mhuge", "mhuge * 1.",
"1. // huge", "huge // 1.", "1. // mhuge", "mhuge // 1.",
"1. / huge", "huge / 1.", "1. / mhuge", "mhuge / 1.",
"1. ** huge", "huge ** 1.", "1. ** mhuge", "mhuge ** 1.",
"math.sin(huge)", "math.sin(mhuge)",
"math.sqrt(huge)", "math.sqrt(mhuge)", # should do better
"math.floor(huge)", "math.floor(mhuge)"]:
self.assertRaises(OverflowError, eval, test, namespace)
# XXX Perhaps float(shuge) can raise OverflowError on some box?
# The comparison should not.
self.assertNotEqual(float(shuge), int(shuge),
"float(shuge) should not equal int(shuge)")
def test_logs(self):
import math
LOG10E = math.log10(math.e)
for exp in range(10) + [100, 1000, 10000]:
value = 10 ** exp
log10 = math.log10(value)
self.assertAlmostEqual(log10, exp)
# log10(value) == exp, so log(value) == log10(value)/log10(e) ==
# exp/LOG10E
expected = exp / LOG10E
log = math.log(value)
self.assertAlmostEqual(log, expected)
for bad in -(1L << 10000), -2L, 0L:
self.assertRaises(ValueError, math.log, bad)
self.assertRaises(ValueError, math.log10, bad)
def test_mixed_compares(self):
eq = self.assertEqual
import math
import sys
# We're mostly concerned with that mixing floats and longs does the
# right stuff, even when longs are too large to fit in a float.
# The safest way to check the results is to use an entirely different
# method, which we do here via a skeletal rational class (which
# represents all Python ints, longs and floats exactly).
class Rat:
def __init__(self, value):
if isinstance(value, (int, long)):
self.n = value
self.d = 1
elif isinstance(value, float):
# Convert to exact rational equivalent.
f, e = math.frexp(abs(value))
assert f == 0 or 0.5 <= f < 1.0
# |value| = f * 2**e exactly
# Suck up CHUNK bits at a time; 28 is enough so that we suck
# up all bits in 2 iterations for all known binary double-
# precision formats, and small enough to fit in an int.
CHUNK = 28
top = 0
# invariant: |value| = (top + f) * 2**e exactly
while f:
f = math.ldexp(f, CHUNK)
digit = int(f)
assert digit >> CHUNK == 0
top = (top << CHUNK) | digit
f -= digit
assert 0.0 <= f < 1.0
e -= CHUNK
# Now |value| = top * 2**e exactly.
if e >= 0:
n = top << e
d = 1
else:
n = top
d = 1 << -e
if value < 0:
n = -n
self.n = n
self.d = d
assert float(n) / float(d) == value
else:
raise TypeError("can't deal with %r" % val)
def __cmp__(self, other):
if not isinstance(other, Rat):
other = Rat(other)
return cmp(self.n * other.d, self.d * other.n)
cases = [0, 0.001, 0.99, 1.0, 1.5, 1e20, 1e200]
# 2**48 is an important boundary in the internals. 2**53 is an
# important boundary for IEEE double precision.
for t in 2.0**48, 2.0**50, 2.0**53:
cases.extend([t - 1.0, t - 0.3, t, t + 0.3, t + 1.0,
long(t-1), long(t), long(t+1)])
cases.extend([0, 1, 2, sys.maxint, float(sys.maxint)])
# 1L<<20000 should exceed all double formats. long(1e200) is to
# check that we get equality with 1e200 above.
t = long(1e200)
cases.extend([0L, 1L, 2L, 1L << 20000, t-1, t, t+1])
cases.extend([-x for x in cases])
for x in cases:
Rx = Rat(x)
for y in cases:
Ry = Rat(y)
Rcmp = cmp(Rx, Ry)
xycmp = cmp(x, y)
eq(Rcmp, xycmp, Frm("%r %r %d %d", x, y, Rcmp, xycmp))
eq(x == y, Rcmp == 0, Frm("%r == %r %d", x, y, Rcmp))
eq(x != y, Rcmp != 0, Frm("%r != %r %d", x, y, Rcmp))
eq(x < y, Rcmp < 0, Frm("%r < %r %d", x, y, Rcmp))
eq(x <= y, Rcmp <= 0, Frm("%r <= %r %d", x, y, Rcmp))
eq(x > y, Rcmp > 0, Frm("%r > %r %d", x, y, Rcmp))
eq(x >= y, Rcmp >= 0, Frm("%r >= %r %d", x, y, Rcmp))
def test_main():
test_support.run_unittest(LongTest)
if __name__ == "__main__":
test_main()
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