import unittest, os, tempfile

class PyFileTest(unittest.TestCase):

	def get_tmpfile(self):
		tmpfile = os.path.join(tempfile.gettempdir(), "test.txt")
		return tmpfile

	def __testfile__(self, mode, strings):

		tmpfile = self.get_tmpfile()

		for a in strings:
			fp = open(tmpfile, mode)
			fp.write(a)
			fp.close()

		fp = open(tmpfile, "r")
		data = fp.read()
		fp.close()

		if mode == 'a':
			ans = "".join(strings)
		else:
			ans = strings[-1]

		assert data == ans, "expected [%s], got [%s]" % (ans, data)

		os.remove(tmpfile)

	def testAppend(self):
		"""test appending to a file"""

		self.__testfile__("a", ['one long string', 'one string'])

	def testWrite(self):
		"""test writing to a file"""

		self.__testfile__("w", ['one long string', 'one string'])

	def testSeek(self):
		"""test seeking into a file"""

		# http://python.org/doc/current/tut/node9.html#SECTION009210000000000000000

		tmpfile = self.get_tmpfile()

		buf = '0123456789abcdef'

		fp = open(tmpfile, "w")
		fp.write(buf)
		fp.close()

		fp = open(tmpfile, "r")

		fp.seek(5) # Go to the 5th byte in the file
		c = fp.read(1)
		assert c == buf[5], "expected [%s], got [%s]" % (buf[5], c)

		fp.seek(-3, 2) # Go to the 3rd byte before the end
		c = fp.read(1)
		assert c == buf[-3], "expected [%s], got [%s]" % (buf[-3], c)

		fp.close()
		os.remove(tmpfile)

if __name__ == '__main__':
	unittest.main()