refactor: no fees on duplicate payment report

Signed-off-by: Gregory Hill <[email protected]>

crates/relay/src/lib.rs

@@ -278,6 +278,7 @@ pub mod pallet {
             ext::security::ensure_parachain_status_not_shutdown::<T>()?;
             let signer = ensure_signed(origin)?;
 
+            // transactions must be unique
             ensure!(raw_txs.0 != raw_txs.1, Error::<T>::DuplicateTransaction);
 
             let parse_and_verify = |raw_tx, raw_proof| -> Result<Transaction, DispatchError> {
@@ -325,7 +326,8 @@ pub mod pallet {
                     ext::sla::event_update_vault_sla::<T>(&signer, ext::sla::Action::TheftReport)?;
                     Self::deposit_event(<Event<T>>::VaultDoublePayment(vault_id, left_tx_id, right_tx_id));
 
-                    Ok(().into())
+                    // don't take tx fees on success
+                    Ok(Pays::No.into())
                 }
                 _ => Err(Error::<T>::InvalidTransaction.into()),
             }

crates/relay/src/tests.rs

@@ -154,10 +154,8 @@ fn build_dummy_transaction_from_input_with_output_and_op_return(
     let mut builder = TransactionBuilder::new();
     builder.with_version(1).add_input(
         TransactionInputBuilder::new()
-            .with_coinbase(false)
+            .with_source(TransactionInputSource::FromOutput(prev_hash, 1))
             .with_sequence(4294967295)
-            .with_previous_index(1)
-            .with_previous_hash(prev_hash)
             .with_p2pkh(public_key, vec![1u8; 32])
             .build(),
     );