Viewing file:  test_bufio.py (2.58 KB) -rw-r--r--
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import unittest
from test import support
from test.support import os_helper
import io # C implementation.
import _pyio as pyio # Python implementation.
# Simple test to ensure that optimizations in the IO library deliver the
# expected results. For best testing, run this under a debug-build Python too
# (to exercise asserts in the C code).
lengths = list(range(1, 257)) + [512, 1000, 1024, 2048, 4096, 8192, 10000,
16384, 32768, 65536, 1000000]
class BufferSizeTest:
def try_one(self, s):
# Write s + "\n" + s to file, then open it and ensure that successive
# .readline()s deliver what we wrote.
# Ensure we can open TESTFN for writing.
os_helper.unlink(os_helper.TESTFN)
# Since C doesn't guarantee we can write/read arbitrary bytes in text
# files, use binary mode.
f = self.open(os_helper.TESTFN, "wb")
try:
# write once with \n and once without
f.write(s)
f.write(b"\n")
f.write(s)
f.close()
f = open(os_helper.TESTFN, "rb")
line = f.readline()
self.assertEqual(line, s + b"\n")
line = f.readline()
self.assertEqual(line, s)
line = f.readline()
self.assertFalse(line) # Must be at EOF
f.close()
finally:
os_helper.unlink(os_helper.TESTFN)
def drive_one(self, pattern):
for length in lengths:
# Repeat string 'pattern' as often as needed to reach total length
# 'length'. Then call try_one with that string, a string one larger
# than that, and a string one smaller than that. Try this with all
# small sizes and various powers of 2, so we exercise all likely
# stdio buffer sizes, and "off by one" errors on both sides.
q, r = divmod(length, len(pattern))
teststring = pattern * q + pattern[:r]
self.assertEqual(len(teststring), length)
self.try_one(teststring)
self.try_one(teststring + b"x")
self.try_one(teststring[:-1])
def test_primepat(self):
# A pattern with prime length, to avoid simple relationships with
# stdio buffer sizes.
self.drive_one(b"1234567890\00\01\02\03\04\05\06")
def test_nullpat(self):
self.drive_one(b'\0' * 1000)
class CBufferSizeTest(BufferSizeTest, unittest.TestCase):
open = io.open
class PyBufferSizeTest(BufferSizeTest, unittest.TestCase):
open = staticmethod(pyio.open)
if __name__ == "__main__":
unittest.main()
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