test_packing.py 文件源码

def check(self, fmt, value):
        from random import randrange
        # build a buffer which is surely big enough to contain what we need
        # and check:
        #   1) that we correctly write the bytes we expect
        #   2) that we do NOT write outside the bounds
        #
        pattern = [six.int2byte(randrange(256)) for _ in range(256)]
        pattern = b''.join(pattern)
        buf = bytearray(pattern)
        buf2 = bytearray(pattern)
        offset = 16
        pack_into(ord(fmt), buf, offset, value)
        struct.pack_into(fmt, buf2, offset, value)
        assert buf == buf2
        #
        # check that it raises if it's out of bound
        out_of_bound = 256-struct.calcsize(fmt)+1
        pytest.raises(IndexError, "pack_into(ord(fmt), buf, out_of_bound, value)")