def test_swapcase(self, size):
        SUBSTR = "aBcDeFG12.'\xa9\x00"
        sublen = len(SUBSTR)
        repeats = size // sublen + 2
        s = SUBSTR * repeats
        s = s.swapcase()
        self.assertEquals(len(s), sublen * repeats)
        self.assertEquals(s[:sublen * 3], SUBSTR.swapcase() * 3)
        self.assertEquals(s[-sublen * 3:], SUBSTR.swapcase() * 3)