cpython/Lib/test/test_bufio.py

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import unittest
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from test import test_support as support
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import io # C implementation.
import _pyio as pyio # Python implementation.
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# 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]
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class BufferSizeTest(unittest.TestCase):
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.
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support.unlink(support.TESTFN)
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# Since C doesn't guarantee we can write/read arbitrary bytes in text
# files, use binary mode.
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f = self.open(support.TESTFN, "wb")
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try:
# write once with \n and once without
f.write(s)
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f.write(b"\n")
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f.write(s)
f.close()
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f = open(support.TESTFN, "rb")
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line = f.readline()
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self.assertEqual(line, s + b"\n")
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line = f.readline()
self.assertEqual(line, s)
line = f.readline()
self.assertFalse(line) # Must be at EOF
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f.close()
finally:
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support.unlink(support.TESTFN)
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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)
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self.try_one(teststring + b"x")
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self.try_one(teststring[:-1])
def test_primepat(self):
# A pattern with prime length, to avoid simple relationships with
# stdio buffer sizes.
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self.drive_one(b"1234567890\00\01\02\03\04\05\06")
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def test_nullpat(self):
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self.drive_one(bytes(1000))
class CBufferSizeTest(BufferSizeTest):
open = io.open
class PyBufferSizeTest(BufferSizeTest):
open = staticmethod(pyio.open)
class BuiltinBufferSizeTest(BufferSizeTest):
open = open
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def test_main():
support.run_unittest(CBufferSizeTest, PyBufferSizeTest, BuiltinBufferSizeTest)
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if __name__ == "__main__":
test_main()