import unittest

from test import test_support

# Simple test to ensure that optimizations in fileobject.c deliver

# the expected results.  For best testing, run this under a debug-build

# Python too (to exercise asserts in the C code).

lengths = range(1, 257) + [512, 1000, 1024, 2048, 4096, 8192, 10000,

                           16384, 32768, 65536, 1000000]

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.

        test_support.unlink(test_support.TESTFN)

        # Since C doesn't guarantee we can write/read arbitrary bytes in text

        # files, use binary mode.

        f = open(test_support.TESTFN, "wb")

        try:

            # write once with \n and once without

            f.write(s)

            f.write("\n")

            f.write(s)

            f.close()

            f = open(test_support.TESTFN, "rb")

            line = f.readline()

            self.assertEqual(line, s + "\n")

            line = f.readline()

            self.assertEqual(line, s)

            line = f.readline()

            self.assert_(not line) # Must be at EOF

            f.close()

        finally:

            test_support.unlink(test_support.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 + "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("1234567890\00\01\02\03\04\05\06")

    def test_nullpat(self):

        self.drive_one("\0" * 1000)

def test_main():

    test_support.run_unittest(BufferSizeTest)

if __name__ == "__main__":

    test_main()