How do I create Hash in tests?

Question

I have a function that creates hash from AccountId's.

#[pallet::call_index(2)]
#[pallet::weight(10_000 + T::DbWeight::get().writes(1).ref_time())]
pub fn connection_request(origin: OriginFor<T>, to: T::AccountId) -> DispatchResult {
    let who = ensure_signed(origin)?;

    let xor = Self::create_xor(&who, &to);
    ...

impl<T: Config> Pallet<T> {
    fn create_xor<Input: Encode>(a: &Input, b: &Input) -> T::Hash {
        let mut bytes_who = a.encode();
        let bytes_to = b.encode();

        bytes_who.iter_mut().zip(bytes_to.iter()).for_each(|(x1, x2)| *x1 ^= *x2);

        T::Hash::decode(&mut bytes_who.as_slice()).expect("all bytes are valid accounts, and the source of these bytes is the xor of two other accounts, thus this must also be a valid account/hash. qed",)
    }
}

And in my tests, create_xor fails with Error { cause: None, desc: "Not enough data to fill buffer" }

#[test]
fn connection_request_should_work() {
    new_test_ext().execute_with(|| {
        System::set_block_number(1);
        assert_ok!(MyPallet::connection_request(RuntimeOrigin::signed(1), 2));
        ...
    });
}

What is the reason I get this error and how do I solve it?

Answer 1

Then length of an encoded AccountId seems to be shorter than a Hash.
The decoding therefore fails, since "Not enough data to fill buffer" for that hash.

What is the reason I get this error and how do I solve it?

I don't know what you are trying to do. Maybe use a builtin hash function like sp_core::keccak_256?