Lib/test/test_gzip.py

   1 #! /usr/bin/env python
   2 """Test script for the gzip module.
   3 """
   4
   5 import unittest
   6 from test import test_support
   7 import os
   8 import io
   9 import struct
  10 gzip = test_support.import_module('gzip')
  11
  12 data1 = """  int length=DEFAULTALLOC, err = Z_OK;
  13   PyObject *RetVal;
  14   int flushmode = Z_FINISH;
  15   unsigned long start_total_out;
  16
  17 """
  18
  19 data2 = """/* zlibmodule.c -- gzip-compatible data compression */
  20 /* See http://www.gzip.org/zlib/
  21 /* See http://www.winimage.com/zLibDll for Windows */
  22 """
  23
  24
  25 class TestGzip(unittest.TestCase):
  26     filename = test_support.TESTFN
  27
  28     def setUp(self):
  29         test_support.unlink(self.filename)
  30
  31     def tearDown(self):
  32         test_support.unlink(self.filename)
  33
  34
  35     def test_write(self):
  36         f = gzip.GzipFile(self.filename, 'wb') ; f.write(data1 * 50)
  37
  38         # Try flush and fileno.
  39         f.flush()
  40         f.fileno()
  41         if hasattr(os, 'fsync'):
  42             os.fsync(f.fileno())
  43         f.close()
  44
  45         # Test multiple close() calls.
  46         f.close()
  47
  48     def test_read(self):
  49         self.test_write()
  50         # Try reading.
  51         f = gzip.GzipFile(self.filename, 'r') ; d = f.read() ; f.close()
  52         self.assertEqual(d, data1*50)
  53
  54     def test_append(self):
  55         self.test_write()
  56         # Append to the previous file
  57         f = gzip.GzipFile(self.filename, 'ab') ; f.write(data2 * 15) ; f.close()
  58
  59         f = gzip.GzipFile(self.filename, 'rb') ; d = f.read() ; f.close()
  60         self.assertEqual(d, (data1*50) + (data2*15))
  61
  62     def test_many_append(self):
  63         # Bug #1074261 was triggered when reading a file that contained
  64         # many, many members.  Create such a file and verify that reading it
  65         # works.
  66         f = gzip.open(self.filename, 'wb', 9)
  67         f.write('a')
  68         f.close()
  69         for i in range(0,200):
  70             f = gzip.open(self.filename, "ab", 9) # append
  71             f.write('a')
  72             f.close()
  73
  74         # Try reading the file
  75         zgfile = gzip.open(self.filename, "rb")
  76         contents = ""
  77         while 1:
  78             ztxt = zgfile.read(8192)
  79             contents += ztxt
  80             if not ztxt: break
  81         zgfile.close()
  82         self.assertEquals(contents, 'a'*201)
  83
  84     def test_buffered_reader(self):
  85         # Issue #7471: a GzipFile can be wrapped in a BufferedReader for
  86         # performance.
  87         self.test_write()
  88
  89         f = gzip.GzipFile(self.filename, 'rb')
  90         with io.BufferedReader(f) as r:
  91             lines = [line for line in r]
  92
  93         self.assertEqual(lines, 50 * data1.splitlines(True))
  94
  95     def test_readline(self):
  96         self.test_write()
  97         # Try .readline() with varying line lengths
  98
  99         f = gzip.GzipFile(self.filename, 'rb')
 100         line_length = 0
 101         while 1:
 102             L = f.readline(line_length)
 103             if L == "" and line_length != 0: break
 104             self.assertTrue(len(L) <= line_length)
 105             line_length = (line_length + 1) % 50
 106         f.close()
 107
 108     def test_readlines(self):
 109         self.test_write()
 110         # Try .readlines()
 111
 112         f = gzip.GzipFile(self.filename, 'rb')
 113         L = f.readlines()
 114         f.close()
 115
 116         f = gzip.GzipFile(self.filename, 'rb')
 117         while 1:
 118             L = f.readlines(150)
 119             if L == []: break
 120         f.close()
 121
 122     def test_seek_read(self):
 123         self.test_write()
 124         # Try seek, read test
 125
 126         f = gzip.GzipFile(self.filename)
 127         while 1:
 128             oldpos = f.tell()
 129             line1 = f.readline()
 130             if not line1: break
 131             newpos = f.tell()
 132             f.seek(oldpos)  # negative seek
 133             if len(line1)>10:
 134                 amount = 10
 135             else:
 136                 amount = len(line1)
 137             line2 = f.read(amount)
 138             self.assertEqual(line1[:amount], line2)
 139             f.seek(newpos)  # positive seek
 140         f.close()
 141
 142     def test_seek_whence(self):
 143         self.test_write()
 144         # Try seek(whence=1), read test
 145
 146         f = gzip.GzipFile(self.filename)
 147         f.read(10)
 148         f.seek(10, whence=1)
 149         y = f.read(10)
 150         f.close()
 151         self.assertEquals(y, data1[20:30])
 152
 153     def test_seek_write(self):
 154         # Try seek, write test
 155         f = gzip.GzipFile(self.filename, 'w')
 156         for pos in range(0, 256, 16):
 157             f.seek(pos)
 158             f.write('GZ\n')
 159         f.close()
 160
 161     def test_mode(self):
 162         self.test_write()
 163         f = gzip.GzipFile(self.filename, 'r')
 164         self.assertEqual(f.myfileobj.mode, 'rb')
 165         f.close()
 166
 167     def test_1647484(self):
 168         for mode in ('wb', 'rb'):
 169             f = gzip.GzipFile(self.filename, mode)
 170             self.assertTrue(hasattr(f, "name"))
 171             self.assertEqual(f.name, self.filename)
 172             f.close()
 173
 174     def test_mtime(self):
 175         mtime = 123456789
 176         fWrite = gzip.GzipFile(self.filename, 'w', mtime = mtime)
 177         fWrite.write(data1)
 178         fWrite.close()
 179         fRead = gzip.GzipFile(self.filename)
 180         dataRead = fRead.read()
 181         self.assertEqual(dataRead, data1)
 182         self.assertTrue(hasattr(fRead, 'mtime'))
 183         self.assertEqual(fRead.mtime, mtime)
 184         fRead.close()
 185
 186     def test_metadata(self):
 187         mtime = 123456789
 188
 189         fWrite = gzip.GzipFile(self.filename, 'w', mtime = mtime)
 190         fWrite.write(data1)
 191         fWrite.close()
 192
 193         fRead = open(self.filename, 'rb')
 194
 195         # see RFC 1952: http://www.faqs.org/rfcs/rfc1952.html
 196
 197         idBytes = fRead.read(2)
 198         self.assertEqual(idBytes, '\x1f\x8b') # gzip ID
 199
 200         cmByte = fRead.read(1)
 201         self.assertEqual(cmByte, '\x08') # deflate
 202
 203         flagsByte = fRead.read(1)
 204         self.assertEqual(flagsByte, '\x08') # only the FNAME flag is set
 205
 206         mtimeBytes = fRead.read(4)
 207         self.assertEqual(mtimeBytes, struct.pack('<i', mtime)) # little-endian
 208
 209         xflByte = fRead.read(1)
 210         self.assertEqual(xflByte, '\x02') # maximum compression
 211
 212         osByte = fRead.read(1)
 213         self.assertEqual(osByte, '\xff') # OS "unknown" (OS-independent)
 214
 215         # Since the FNAME flag is set, the zero-terminated filename follows.
 216         # RFC 1952 specifies that this is the name of the input file, if any.
 217         # However, the gzip module defaults to storing the name of the output
 218         # file in this field.
 219         nameBytes = fRead.read(len(self.filename) + 1)
 220         self.assertEqual(nameBytes, self.filename + '\x00')
 221
 222         # Since no other flags were set, the header ends here.
 223         # Rather than process the compressed data, let's seek to the trailer.
 224         fRead.seek(os.stat(self.filename).st_size - 8)
 225
 226         crc32Bytes = fRead.read(4) # CRC32 of uncompressed data [data1]
 227         self.assertEqual(crc32Bytes, '\xaf\xd7d\x83')
 228
 229         isizeBytes = fRead.read(4)
 230         self.assertEqual(isizeBytes, struct.pack('<i', len(data1)))
 231
 232         fRead.close()
 233
 234     def test_with_open(self):
 235         # GzipFile supports the context management protocol
 236         with gzip.GzipFile(self.filename, "wb") as f:
 237             f.write(b"xxx")
 238         f = gzip.GzipFile(self.filename, "rb")
 239         f.close()
 240         try:
 241             with f:
 242                 pass
 243         except ValueError:
 244             pass
 245         else:
 246             self.fail("__enter__ on a closed file didn't raise an exception")
 247         try:
 248             with gzip.GzipFile(self.filename, "wb") as f:
 249                 1 // 0
 250         except ZeroDivisionError:
 251             pass
 252         else:
 253             self.fail("1 // 0 didn't raise an exception")
 254
 255     def test_zero_padded_file(self):
 256         with gzip.GzipFile(self.filename, "wb") as f:
 257             f.write(data1 * 50)
 258
 259         # Pad the file with zeroes
 260         with open(self.filename, "ab") as f:
 261             f.write("\x00" * 50)
 262
 263         with gzip.GzipFile(self.filename, "rb") as f:
 264             d = f.read()
 265             self.assertEqual(d, data1 * 50, "Incorrect data in file")
 266
 267 def test_main(verbose=None):
 268     test_support.run_unittest(TestGzip)
 269
 270 if __name__ == "__main__":
 271     test_main(verbose=True)