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 # Test flush() with the various options, using all the different levels
  80 # in order to provide more variations.
  81 for sync in [zlib.Z_NO_FLUSH, zlib.Z_SYNC_FLUSH, zlib.Z_FULL_FLUSH]:
  82     for level in range(10):
  83         obj = zlib.compressobj( level )
  84         d = obj.compress( buf[:3000] )
  85         d = d + obj.flush( sync )
  86         d = d + obj.compress( buf[3000:] )
  87         d = d + obj.flush()
  88         if zlib.decompress(d) != buf:
  89             print "Decompress failed: flush mode=%i, level=%i" % (sync,level)
  90         del obj
  91
  92 # Test for the odd flushing bugs noted in 2.0, and hopefully fixed in 2.1
  93
  94 import random
  95 random.seed(1)
  96
  97 print 'Testing on 17K of random data'
  98
  99 # Create compressor and decompressor objects
 100 c=zlib.compressobj(9)
 101 d=zlib.decompressobj()
 102
 103 # Try 17K of data
 104 # generate random data stream
 105 a=""
 106 for i in range(17*1024):
 107     a=a+chr(random.randint(0,255))
 108
 109 # compress, sync-flush, and decompress
 110 t = d.decompress( c.compress(a)+c.flush(zlib.Z_SYNC_FLUSH) )
 111
 112 # if decompressed data is different from the input data, choke.
 113 if len(t) != len(a):
 114     print len(a),len(t),len(d.unused_data)
 115     raise TestFailed, "output of 17K doesn't match"
 116
 117 def ignore():
 118     """An empty function with a big string.
 119
 120     Make the compression algorithm work a little harder.
 121     """
 122
 123     """
 124 LAERTES
 125
 126        O, fear me not.
 127        I stay too long: but here my father comes.
 128
 129        Enter POLONIUS
 130
 131        A double blessing is a double grace,
 132        Occasion smiles upon a second leave.
 133
 134 LORD POLONIUS
 135
 136        Yet here, Laertes! aboard, aboard, for shame!
 137        The wind sits in the shoulder of your sail,
 138        And you are stay'd for. There; my blessing with thee!
 139        And these few precepts in thy memory
 140        See thou character. Give thy thoughts no tongue,
 141        Nor any unproportioned thought his act.
 142        Be thou familiar, but by no means vulgar.
 143        Those friends thou hast, and their adoption tried,
 144        Grapple them to thy soul with hoops of steel;
 145        But do not dull thy palm with entertainment
 146        Of each new-hatch'd, unfledged comrade. Beware
 147        Of entrance to a quarrel, but being in,
 148        Bear't that the opposed may beware of thee.
 149        Give every man thy ear, but few thy voice;
 150        Take each man's censure, but reserve thy judgment.
 151        Costly thy habit as thy purse can buy,
 152        But not express'd in fancy; rich, not gaudy;
 153        For the apparel oft proclaims the man,
 154        And they in France of the best rank and station
 155        Are of a most select and generous chief in that.
 156        Neither a borrower nor a lender be;
 157        For loan oft loses both itself and friend,
 158        And borrowing dulls the edge of husbandry.
 159        This above all: to thine ownself be true,
 160        And it must follow, as the night the day,
 161        Thou canst not then be false to any man.
 162        Farewell: my blessing season this in thee!
 163
 164 LAERTES
 165
 166        Most humbly do I take my leave, my lord.
 167
 168 LORD POLONIUS
 169
 170        The time invites you; go; your servants tend.
 171
 172 LAERTES
 173
 174        Farewell, Ophelia; and remember well
 175        What I have said to you.
 176
 177 OPHELIA
 178
 179        'Tis in my memory lock'd,
 180        And you yourself shall keep the key of it.
 181
 182 LAERTES
 183
 184        Farewell.
 185 """