Lib/test/test_zlib.py

   1 import zlib
   2 import sys
   3 import imp
   4 from test.test_support import TestFailed
   5
   6 try:
   7     t = imp.find_module('test_zlib')
   8     file = t[0]
   9 except ImportError:
  10     file = open(__file__)
  11 buf = file.read() * 8
  12 file.close()
  13
  14 # test the checksums (hex so the test doesn't break on 64-bit machines)
  15 def fix(x):
  16     return "0x%x" % (x & 0xffffffffL)
  17 print fix(zlib.crc32('penguin')), fix(zlib.crc32('penguin', 1))
  18 print fix(zlib.adler32('penguin')), fix(zlib.adler32('penguin', 1))
  19
  20 # make sure we generate some expected errors
  21 try:
  22     zlib.compress('ERROR', zlib.MAX_WBITS + 1)
  23 except zlib.error, msg:
  24     print "expecting", msg
  25 try:
  26     zlib.compressobj(1, 8, 0)
  27 except ValueError, msg:
  28     print "expecting", msg
  29 try:
  30     zlib.decompressobj(0)
  31 except ValueError, msg:
  32     print "expecting", msg
  33
  34 x = zlib.compress(buf)
  35 y = zlib.decompress(x)
  36 if buf != y:
  37     print "normal compression/decompression failed"
  38 else:
  39     print "normal compression/decompression succeeded"
  40
  41 buf = buf * 16
  42
  43 co = zlib.compressobj(8, 8, -15)
  44 x1 = co.compress(buf)
  45 x2 = co.flush()
  46 try:
  47     co.flush()
  48     print "Oops - second flush worked when it should not have!"
  49 except zlib.error:
  50     pass
  51
  52 x = x1 + x2
  53
  54 dc = zlib.decompressobj(-15)
  55 y1 = dc.decompress(x)
  56 y2 = dc.flush()
  57 y = y1 + y2
  58 if buf != y:
  59     print "compress/decompression obj failed"
  60 else:
  61     print "compress/decompression obj succeeded"
  62
  63 co = zlib.compressobj(2, 8, -12, 9, 1)
  64 bufs = []
  65 for i in range(0, len(buf), 256):
  66     bufs.append(co.compress(buf[i:i+256]))
  67 bufs.append(co.flush())
  68 combuf = ''.join(bufs)
  69
  70 decomp1 = zlib.decompress(combuf, -12, -5)
  71 if decomp1 != buf:
  72     print "decompress with init options failed"
  73 else:
  74     print "decompress with init options succeeded"
  75
  76 deco = zlib.decompressobj(-12)
  77 bufs = []
  78 for i in range(0, len(combuf), 128):
  79     bufs.append(deco.decompress(combuf[i:i+128]))
  80 bufs.append(deco.flush())
  81 decomp2 = ''.join(bufs)
  82 if decomp2 != buf:
  83     print "decompressobj with init options failed"
  84 else:
  85     print "decompressobj with init options succeeded"
  86
  87 print "should be '':", `deco.unconsumed_tail`
  88
  89 # Check a decompression object with max_length specified
  90 deco = zlib.decompressobj(-12)
  91 cb = combuf
  92 bufs = []
  93 while cb:
  94     max_length = 1 + len(cb)/10
  95     chunk = deco.decompress(cb, max_length)
  96     if len(chunk) > max_length:
  97         print 'chunk too big (%d>%d)' % (len(chunk),max_length)
  98     bufs.append(chunk)
  99     cb = deco.unconsumed_tail
 100 bufs.append(deco.flush())
 101 decomp2 = ''.join(buf)
 102 if decomp2 != buf:
 103     print "max_length decompressobj failed"
 104 else:
 105     print "max_length decompressobj succeeded"
 106
 107 # Misc tests of max_length
 108 deco = zlib.decompressobj(-12)
 109 try:
 110     deco.decompress("", -1)
 111 except ValueError:
 112     pass
 113 else:
 114     print "failed to raise value error on bad max_length"
 115 print "unconsumed_tail should be '':", `deco.unconsumed_tail`
 116
 117 # Test flush() with the various options, using all the different levels
 118 # in order to provide more variations.
 119 sync_opt = ['Z_NO_FLUSH', 'Z_SYNC_FLUSH', 'Z_FULL_FLUSH']
 120 sync_opt = [getattr(zlib, opt) for opt in sync_opt if hasattr(zlib, opt)]
 121
 122 for sync in sync_opt:
 123     for level in range(10):
 124         obj = zlib.compressobj( level )
 125         d = obj.compress( buf[:3000] )
 126         d = d + obj.flush( sync )
 127         d = d + obj.compress( buf[3000:] )
 128         d = d + obj.flush()
 129         if zlib.decompress(d) != buf:
 130             print "Decompress failed: flush mode=%i, level=%i" % (sync,level)
 131         del obj
 132
 133 # Test for the odd flushing bugs noted in 2.0, and hopefully fixed in 2.1
 134
 135 import random
 136 random.seed(1)
 137
 138 print 'Testing on 17K of random data'
 139
 140 if hasattr(zlib, 'Z_SYNC_FLUSH'):
 141
 142     # Create compressor and decompressor objects
 143     c=zlib.compressobj(9)
 144     d=zlib.decompressobj()
 145
 146     # Try 17K of data
 147     # generate random data stream
 148     a=""
 149     for i in range(17*1024):
 150         a=a+chr(random.randint(0,255))
 151
 152     # compress, sync-flush, and decompress
 153     t = d.decompress( c.compress(a)+c.flush(zlib.Z_SYNC_FLUSH) )
 154
 155     # if decompressed data is different from the input data, choke.
 156     if len(t) != len(a):
 157         print len(a),len(t),len(d.unused_data)
 158         raise TestFailed, "output of 17K doesn't match"
 159
 160 def ignore():
 161     """An empty function with a big string.
 162
 163     Make the compression algorithm work a little harder.
 164     """
 165
 166     """
 167 LAERTES
 168
 169        O, fear me not.
 170        I stay too long: but here my father comes.
 171
 172        Enter POLONIUS
 173
 174        A double blessing is a double grace,
 175        Occasion smiles upon a second leave.
 176
 177 LORD POLONIUS
 178
 179        Yet here, Laertes! aboard, aboard, for shame!
 180        The wind sits in the shoulder of your sail,
 181        And you are stay'd for. There; my blessing with thee!
 182        And these few precepts in thy memory
 183        See thou character. Give thy thoughts no tongue,
 184        Nor any unproportioned thought his act.
 185        Be thou familiar, but by no means vulgar.
 186        Those friends thou hast, and their adoption tried,
 187        Grapple them to thy soul with hoops of steel;
 188        But do not dull thy palm with entertainment
 189        Of each new-hatch'd, unfledged comrade. Beware
 190        Of entrance to a quarrel, but being in,
 191        Bear't that the opposed may beware of thee.
 192        Give every man thy ear, but few thy voice;
 193        Take each man's censure, but reserve thy judgment.
 194        Costly thy habit as thy purse can buy,
 195        But not express'd in fancy; rich, not gaudy;
 196        For the apparel oft proclaims the man,
 197        And they in France of the best rank and station
 198        Are of a most select and generous chief in that.
 199        Neither a borrower nor a lender be;
 200        For loan oft loses both itself and friend,
 201        And borrowing dulls the edge of husbandry.
 202        This above all: to thine ownself be true,
 203        And it must follow, as the night the day,
 204        Thou canst not then be false to any man.
 205        Farewell: my blessing season this in thee!
 206
 207 LAERTES
 208
 209        Most humbly do I take my leave, my lord.
 210
 211 LORD POLONIUS
 212
 213        The time invites you; go; your servants tend.
 214
 215 LAERTES
 216
 217        Farewell, Ophelia; and remember well
 218        What I have said to you.
 219
 220 OPHELIA
 221
 222        'Tis in my memory lock'd,
 223        And you yourself shall keep the key of it.
 224
 225 LAERTES
 226
 227        Farewell.
 228 """