@claudio Thanks. Could you please also check this one. I am not sure if it’s a bug or not
It is impossible to call testUnit method in playground. If you deploy it locally you will be able to call this method with zero arguments from other canisters, but if you try to call it from command line, you will need to provide a single null argument
@chenyan could this be a Motoko2Candid issue? It there some special translation of the empty Motoko tuple to null?
Might be a Candid UI bug. You can call that method from dfx via dfx canister call wmfrn-xyaaa-aaaab-qadea-cai testUnit '(null)' --network ic. When calling from another canister, I think you still need to provide the null argument. Candid subtyping doesn’t allow omitting the null type in arguments.