How to check the checksum of an IPv6 UDP packet

I have to check that the checksum of an IPv6 UDP packet is correct. Wireshark is one solution:

• write the UDP packet into a text file, adhering to the format described here
• in Wireshark, ensure that the checksum will be verified: select Edit > Preferences... > Protocols > UDP, and tick Validate the UDP checksum if possible
• import the packet, with File > Import from Hex Dump...
• for Encapsulation Type, select Raw IPv6

And that's it.

If the provided checksum is incorrect, Wireshark displays the correct one.