text: import unittest
  
  from ctypes import *
  import _ctypes_test
  
  lib = CDLL(_ctypes_test.__file__)
  
  def three_way_cmp(x, y):
      """Return -1 if x < y, 0 if x == y and 1 if x > y"""
      return (x > y) - (x < y)
  
  class LibTest(unittest.TestCase):
      def test_sqrt(self):
          lib.my_sqrt.argtypes = c_double,
          lib.my_sqrt.restype = c_double
          self.assertEqual(lib.my_sqrt(4.0), 2.0)
          import math
          self.assertEqual(lib.my_sqrt(2.0), math.sqrt(2.0))
  
      def test_qsort(self):
          comparefunc = CFUNCTYPE(c_int, POINTER(c_char), POINTER(c_char))
          lib.my_qsort.argtypes = c_void_p, c_size_t, c_size_t, comparefunc
          lib.my_qsort.restype = None
  
          def sort(a, b):
              return three_way_cmp(a[0], b[0])
  
          chars = create_string_buffer(b"spam, spam, and spam")
          lib.my_qsort(chars, len(chars)-1, sizeof(c_char), comparefunc(sort))
          self.assertEqual(chars.raw, b"   ,,aaaadmmmnpppsss\x00")
  
  if __name__ == "__main__":
      unittest.main()
  