Lib/test/test_long.py

   1 from test_support import verify, verbose, TestFailed
   2 from string import join
   3 from random import random, randint
   4
   5 # SHIFT should match the value in longintrepr.h for best testing.
   6 SHIFT = 15
   7 BASE = 2 ** SHIFT
   8 MASK = BASE - 1
   9
  10 # Max number of base BASE digits to use in test cases.  Doubling
  11 # this will at least quadruple the runtime.
  12 MAXDIGITS = 10
  13
  14 # build some special values
  15 special = map(long, [0, 1, 2, BASE, BASE >> 1])
  16 special.append(0x5555555555555555L)
  17 special.append(0xaaaaaaaaaaaaaaaaL)
  18 #  some solid strings of one bits
  19 p2 = 4L  # 0 and 1 already added
  20 for i in range(2*SHIFT):
  21     special.append(p2 - 1)
  22     p2 = p2 << 1
  23 del p2
  24 # add complements & negations
  25 special = special + map(lambda x: ~x, special) + \
  26                     map(lambda x: -x, special)
  27
  28 # ------------------------------------------------------------ utilities
  29
  30 # Use check instead of assert so the test still does something
  31 # under -O.
  32
  33 def check(ok, *args):
  34     if not ok:
  35         raise TestFailed, join(map(str, args), " ")
  36
  37 # Get quasi-random long consisting of ndigits digits (in base BASE).
  38 # quasi == the most-significant digit will not be 0, and the number
  39 # is constructed to contain long strings of 0 and 1 bits.  These are
  40 # more likely than random bits to provoke digit-boundary errors.
  41 # The sign of the number is also random.
  42
  43 def getran(ndigits):
  44     verify(ndigits > 0)
  45     nbits_hi = ndigits * SHIFT
  46     nbits_lo = nbits_hi - SHIFT + 1
  47     answer = 0L
  48     nbits = 0
  49     r = int(random() * (SHIFT * 2)) | 1  # force 1 bits to start
  50     while nbits < nbits_lo:
  51         bits = (r >> 1) + 1
  52         bits = min(bits, nbits_hi - nbits)
  53         verify(1 <= bits <= SHIFT)
  54         nbits = nbits + bits
  55         answer = answer << bits
  56         if r & 1:
  57             answer = answer | ((1 << bits) - 1)
  58         r = int(random() * (SHIFT * 2))
  59     verify(nbits_lo <= nbits <= nbits_hi)
  60     if random() < 0.5:
  61         answer = -answer
  62     return answer
  63
  64 # Get random long consisting of ndigits random digits (relative to base
  65 # BASE).  The sign bit is also random.
  66
  67 def getran2(ndigits):
  68     answer = 0L
  69     for i in range(ndigits):
  70         answer = (answer << SHIFT) | randint(0, MASK)
  71     if random() < 0.5:
  72         answer = -answer
  73     return answer
  74
  75 # --------------------------------------------------------------- divmod
  76
  77 def test_division_2(x, y):
  78     q, r = divmod(x, y)
  79     q2, r2 = x/y, x%y
  80     pab, pba = x*y, y*x
  81     check(pab == pba, "multiplication does not commute for", x, y)
  82     check(q == q2, "divmod returns different quotient than / for", x, y)
  83     check(r == r2, "divmod returns different mod than % for", x, y)
  84     check(x == q*y + r, "x != q*y + r after divmod on", x, y)
  85     if y > 0:
  86         check(0 <= r < y, "bad mod from divmod on", x, y)
  87     else:
  88         check(y < r <= 0, "bad mod from divmod on", x, y)
  89
  90 def test_division(maxdigits=MAXDIGITS):
  91     print "long / * % divmod"
  92     digits = range(1, maxdigits+1)
  93     for lenx in digits:
  94         x = getran(lenx)
  95         for leny in digits:
  96             y = getran(leny) or 1L
  97             test_division_2(x, y)
  98
  99 # -------------------------------------------------------------- ~ & | ^
 100
 101 def test_bitop_identities_1(x):
 102     check(x & 0 == 0, "x & 0 != 0 for", x)
 103     check(x | 0 == x, "x | 0 != x for", x)
 104     check(x ^ 0 == x, "x ^ 0 != x for", x)
 105     check(x & -1 == x, "x & -1 != x for", x)
 106     check(x | -1 == -1, "x | -1 != -1 for", x)
 107     check(x ^ -1 == ~x, "x ^ -1 != ~x for", x)
 108     check(x == ~~x, "x != ~~x for", x)
 109     check(x & x == x, "x & x != x for", x)
 110     check(x | x == x, "x | x != x for", x)
 111     check(x ^ x == 0, "x ^ x != 0 for", x)
 112     check(x & ~x == 0, "x & ~x != 0 for", x)
 113     check(x | ~x == -1, "x | ~x != -1 for", x)
 114     check(x ^ ~x == -1, "x ^ ~x != -1 for", x)
 115     check(-x == 1 + ~x == ~(x-1), "not -x == 1 + ~x == ~(x-1) for", x)
 116     for n in range(2*SHIFT):
 117         p2 = 2L ** n
 118         check(x << n >> n == x, "x << n >> n != x for", x, n)
 119         check(x / p2 == x >> n, "x / p2 != x >> n for x n p2", x, n, p2)
 120         check(x * p2 == x << n, "x * p2 != x << n for x n p2", x, n, p2)
 121         check(x & -p2 == x >> n << n == x & ~(p2 - 1),
 122             "not x & -p2 == x >> n << n == x & ~(p2 - 1) for x n p2",
 123             x, n, p2)
 124
 125 def test_bitop_identities_2(x, y):
 126     check(x & y == y & x, "x & y != y & x for", x, y)
 127     check(x | y == y | x, "x | y != y | x for", x, y)
 128     check(x ^ y == y ^ x, "x ^ y != y ^ x for", x, y)
 129     check(x ^ y ^ x == y, "x ^ y ^ x != y for", x, y)
 130     check(x & y == ~(~x | ~y), "x & y != ~(~x | ~y) for", x, y)
 131     check(x | y == ~(~x & ~y), "x | y != ~(~x & ~y) for", x, y)
 132     check(x ^ y == (x | y) & ~(x & y),
 133          "x ^ y != (x | y) & ~(x & y) for", x, y)
 134     check(x ^ y == (x & ~y) | (~x & y),
 135          "x ^ y == (x & ~y) | (~x & y) for", x, y)
 136     check(x ^ y == (x | y) & (~x | ~y),
 137          "x ^ y == (x | y) & (~x | ~y) for", x, y)
 138
 139 def test_bitop_identities_3(x, y, z):
 140     check((x & y) & z == x & (y & z),
 141          "(x & y) & z != x & (y & z) for", x, y, z)
 142     check((x | y) | z == x | (y | z),
 143          "(x | y) | z != x | (y | z) for", x, y, z)
 144     check((x ^ y) ^ z == x ^ (y ^ z),
 145          "(x ^ y) ^ z != x ^ (y ^ z) for", x, y, z)
 146     check(x & (y | z) == (x & y) | (x & z),
 147          "x & (y | z) != (x & y) | (x & z) for", x, y, z)
 148     check(x | (y & z) == (x | y) & (x | z),
 149          "x | (y & z) != (x | y) & (x | z) for", x, y, z)
 150
 151 def test_bitop_identities(maxdigits=MAXDIGITS):
 152     print "long bit-operation identities"
 153     for x in special:
 154         test_bitop_identities_1(x)
 155     digits = range(1, maxdigits+1)
 156     for lenx in digits:
 157         x = getran(lenx)
 158         test_bitop_identities_1(x)
 159         for leny in digits:
 160             y = getran(leny)
 161             test_bitop_identities_2(x, y)
 162             test_bitop_identities_3(x, y, getran((lenx + leny)/2))
 163
 164 # ------------------------------------------------- hex oct repr str atol
 165
 166 def slow_format(x, base):
 167     if (x, base) == (0, 8):
 168         # this is an oddball!
 169         return "0L"
 170     digits = []
 171     sign = 0
 172     if x < 0:
 173         sign, x = 1, -x
 174     while x:
 175         x, r = divmod(x, base)
 176         digits.append(int(r))
 177     digits.reverse()
 178     digits = digits or [0]
 179     return '-'[:sign] + \
 180            {8: '0', 10: '', 16: '0x'}[base] + \
 181            join(map(lambda i: "0123456789ABCDEF"[i], digits), '') + \
 182            "L"
 183
 184 def test_format_1(x):
 185     from string import atol
 186     for base, mapper in (8, oct), (10, repr), (16, hex):
 187         got = mapper(x)
 188         expected = slow_format(x, base)
 189         check(got == expected, mapper.__name__, "returned",
 190               got, "but expected", expected, "for", x)
 191         check(atol(got, 0) == x, 'atol("%s", 0) !=' % got, x)
 192     # str() has to be checked a little differently since there's no
 193     # trailing "L"
 194     got = str(x)
 195     expected = slow_format(x, 10)[:-1]
 196     check(got == expected, mapper.__name__, "returned",
 197           got, "but expected", expected, "for", x)
 198
 199 def test_format(maxdigits=MAXDIGITS):
 200     print "long str/hex/oct/atol"
 201     for x in special:
 202         test_format_1(x)
 203     for i in range(10):
 204         for lenx in range(1, maxdigits+1):
 205             x = getran(lenx)
 206             test_format_1(x)
 207
 208 # ----------------------------------------------------------------- misc
 209
 210 def test_misc(maxdigits=MAXDIGITS):
 211     print "long miscellaneous operations"
 212     import sys
 213
 214     # check the extremes in int<->long conversion
 215     hugepos = sys.maxint
 216     hugeneg = -hugepos - 1
 217     hugepos_aslong = long(hugepos)
 218     hugeneg_aslong = long(hugeneg)
 219     check(hugepos == hugepos_aslong, "long(sys.maxint) != sys.maxint")
 220     check(hugeneg == hugeneg_aslong,
 221         "long(-sys.maxint-1) != -sys.maxint-1")
 222
 223     # long -> int should not fail for hugepos_aslong or hugeneg_aslong
 224     try:
 225         check(int(hugepos_aslong) == hugepos,
 226               "converting sys.maxint to long and back to int fails")
 227     except OverflowError:
 228         raise TestFailed, "int(long(sys.maxint)) overflowed!"
 229     try:
 230         check(int(hugeneg_aslong) == hugeneg,
 231               "converting -sys.maxint-1 to long and back to int fails")
 232     except OverflowError:
 233         raise TestFailed, "int(long(-sys.maxint-1)) overflowed!"
 234
 235     # but long -> int should overflow for hugepos+1 and hugeneg-1
 236     x = hugepos_aslong + 1
 237     try:
 238         int(x)
 239         raise ValueError
 240     except OverflowError:
 241         pass
 242     except:
 243         raise TestFailed, "int(long(sys.maxint) + 1) didn't overflow"
 244
 245     x = hugeneg_aslong - 1
 246     try:
 247         int(x)
 248         raise ValueError
 249     except OverflowError:
 250         pass
 251     except:
 252         raise TestFailed, "int(long(-sys.maxint-1) - 1) didn't overflow"
 253
 254 # ---------------------------------------------------------------- do it
 255
 256 test_division()
 257 test_bitop_identities()
 258 test_format()
 259 test_misc()