from ctypes import *

import unittest



class VarSizeTest(unittest.TestCase):

    def test_resize(self):

        class X(Structure):

            _fields_ = [("item", c_int),

                        ("array", c_int * 1)]



        self.failUnlessEqual(sizeof(X), sizeof(c_int) * 2)

        x = X()

        x.item = 42

        x.array[0] = 100

        self.failUnlessEqual(sizeof(x), sizeof(c_int) * 2)



        # make room for one additional item

        new_size = sizeof(X) + sizeof(c_int) * 1

        resize(x, new_size)

        self.failUnlessEqual(sizeof(x), new_size)

        self.failUnlessEqual((x.item, x.array[0]), (42, 100))



        # make room for 10 additional items

        new_size = sizeof(X) + sizeof(c_int) * 9

        resize(x, new_size)

        self.failUnlessEqual(sizeof(x), new_size)

        self.failUnlessEqual((x.item, x.array[0]), (42, 100))



        # make room for one additional item

        new_size = sizeof(X) + sizeof(c_int) * 1

        resize(x, new_size)

        self.failUnlessEqual(sizeof(x), new_size)

        self.failUnlessEqual((x.item, x.array[0]), (42, 100))



    def test_array_invalid_length(self):

        # cannot create arrays with non-positive size

        self.failUnlessRaises(ValueError, lambda: c_int * -1)

        self.failUnlessRaises(ValueError, lambda: c_int * -3)



    def test_zerosized_array(self):

        array = (c_int * 0)()

        # accessing elements of zero-sized arrays raise IndexError

        self.failUnlessRaises(IndexError, array.__setitem__, 0, None)

        self.failUnlessRaises(IndexError, array.__getitem__, 0)

        self.failUnlessRaises(IndexError, array.__setitem__, 1, None)

        self.failUnlessRaises(IndexError, array.__getitem__, 1)

        self.failUnlessRaises(IndexError, array.__setitem__, -1, None)

        self.failUnlessRaises(IndexError, array.__getitem__, -1)



if __name__ == "__main__":

    unittest.main()

