from __future__ import print_function

import io
import sys

def test(copen):
    fp = copen('wtf.bin', 'wb')
    fp.write(b'\x00' * 8192)
    fp.close()

    fp = copen('wtf.bin', 'r+b')

    print('write:', fp.write(b'\x00' * 4097))

    print('tell before last read', fp.tell())
    print('last read len:', len(fp.read(1)))

    # fp.seek(fp.tell())  # don't help
    print('tell:', fp.tell())
    print('truncate:', fp.truncate())
    print('tell again:', fp.tell())

print('Python {}.{}'.format(*sys.version_info[:2]))

print()
print('Test with builtin open:')
test(open)

print()
print('Test with io.open:')
test(io.open)