Lib/test/test_zlib.py

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