'Check that the appropriate error is thrown for a short file'

def test_short_file(self):

    with open(TEST_FILE_DXT5, 'rb') as f:
        img_file = f.read()
    def short_file():
        im = Image.open(BytesIO(img_file[:(-100)]))
        im.load()
    self.assertRaises(IOError, short_file)
