from test.test_support import verify, TestFailed, TESTFN

# 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).

# 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.  The main driver

# feeds this all small sizes and various powers of 2, so we exercise

# all likely stdio buffer sizes, and "off by one" errors on both

# sides.

def drive_one(pattern, length):

    q, r = divmod(length, len(pattern))

    teststring = pattern * q + pattern[:r]

    verify(len(teststring) == length)

    try_one(teststring)

    try_one(teststring + "x")

    try_one(teststring[:-1])

# Write s + "\n" + s to file, then open it and ensure that successive

# .readline()s deliver what we wrote.

def try_one(s):

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

    # files, use binary mode.

    f = open(TESTFN, "wb")

    # write once with \n and once without

    f.write(s)

    f.write("\n")

    f.write(s)

    f.close()

    f = open(TESTFN, "rb")

    line = f.readline()

    if line != s + "\n":

        raise TestFailed("Expected %r got %r" % (s + "\n", line))

    line = f.readline()

    if line != s:

        raise TestFailed("Expected %r got %r" % (s, line))

    line = f.readline()

    if line:

        raise TestFailed("Expected EOF but got %r" % line)

    f.close()

# A pattern with prime length, to avoid simple relationships with

# stdio buffer sizes.

primepat = "1234567890\00\01\02\03\04\05\06"

nullpat = "\0" * 1000

try:

    for size in range(1, 257) + [512, 1000, 1024, 2048, 4096, 8192, 10000,

                      16384, 32768, 65536, 1000000]:

        drive_one(primepat, size)

        drive_one(nullpat, size)

finally:

    try:

        import os

        os.unlink(TESTFN)

    except:

        pass