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c:\python24\lib \ test \ test_bufio.py



0001 from test.test_support import verify, TestFailed, TESTFN
0002 
0003 # Simple test to ensure that optimizations in fileobject.c deliver
0004 # the expected results.  For best testing, run this under a debug-build
0005 # Python too (to exercise asserts in the C code).
0006 
0007 # Repeat string 'pattern' as often as needed to reach total length
0008 # 'length'.  Then call try_one with that string, a string one larger
0009 # than that, and a string one smaller than that.  The main driver
0010 # feeds this all small sizes and various powers of 2, so we exercise
0011 # all likely stdio buffer sizes, and "off by one" errors on both
0012 # sides.
0013 def drive_one(pattern, length):
0014     q, r = divmod(length, len(pattern))
0015     teststring = pattern * q + pattern[:r]
0016     verify(len(teststring) == length)
0017     try_one(teststring)
0018     try_one(teststring + "x")
0019     try_one(teststring[:-1])
0020 
0021 # Write s + "\n" + s to file, then open it and ensure that successive
0022 # .readline()s deliver what we wrote.
0023 def try_one(s):
0024     # Since C doesn't guarantee we can write/read arbitrary bytes in text
0025     # files, use binary mode.
0026     f = open(TESTFN, "wb")
0027     # write once with \n and once without
0028     f.write(s)
0029     f.write("\n")
0030     f.write(s)
0031     f.close()
0032     f = open(TESTFN, "rb")
0033     line = f.readline()
0034     if line != s + "\n":
0035         raise TestFailed("Expected %r got %r" % (s + "\n", line))
0036     line = f.readline()
0037     if line != s:
0038         raise TestFailed("Expected %r got %r" % (s, line))
0039     line = f.readline()
0040     if line:
0041         raise TestFailed("Expected EOF but got %r" % line)
0042     f.close()
0043 
0044 # A pattern with prime length, to avoid simple relationships with
0045 # stdio buffer sizes.
0046 primepat = "1234567890\00\01\02\03\04\05\06"
0047 
0048 nullpat = "\0" * 1000
0049 
0050 try:
0051     for size in range(1, 257) + [512, 1000, 1024, 2048, 4096, 8192, 10000,
0052                       16384, 32768, 65536, 1000000]:
0053         drive_one(primepat, size)
0054         drive_one(nullpat, size)
0055 finally:
0056     try:
0057         import os
0058         os.unlink(TESTFN)
0059     except:
0060         pass
0061 

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