Fix lp-gateway routers' weight and fee calculations

And adjust the integration tests to use reasonable amounts and verify
the fees being charged.

pallets/liquidity-pools-gateway/routers/src/lib.rs

@@ -33,11 +33,12 @@ use frame_support::{
 	dispatch::{DispatchError, DispatchResult, Weight},
 	ensure,
 	traits::OriginTrait,
+	weights::constants::WEIGHT_REF_TIME_PER_SECOND,
 };
 use pallet_xcm_transactor::{Currency, CurrencyPayment, TransactWeights};
 use scale_info::TypeInfo;
 use sp_core::{bounded::BoundedVec, ConstU32, H160, H256, U256};
-use sp_runtime::traits::{BlakeTwo256, EnsureMul, Hash};
+use sp_runtime::traits::{BlakeTwo256, EnsureAdd, EnsureMul, Hash};
 use sp_std::{boxed::Box, marker::PhantomData, vec::Vec};
 use xcm::{
 	latest::{MultiLocation, OriginKind},
@@ -228,15 +229,18 @@ where
 		let ethereum_xcm_call = get_encoded_ethereum_xcm_call::<T>(self.xcm_domain.clone(), msg)
 			.map_err(|_| DispatchError::Other("encoded ethereum xcm call retrieval"))?;
 
-		// Note: We are using moonbeams calculation for the ref time here and their
-		//       estimate for the PoV.
+		// NOTE: We are using Moonbeam's calculation for the ref time and their estimate
+		// for the PoV.
 		//
-		// 	       - Transact weight: gasLimit * 25000 as moonbeam is doing (Proof size
-		//           limited fixed)
+		// ref_time:
+		// 	GAS_TO_WEIGHT_MULTIPLIER * MAX_GAS_LIMIT + EthereumXcm.transact's Weight + a
+		// bit extra
 		let transact_required_weight_at_most = Weight::from_ref_time(
 			self.xcm_domain
 				.max_gas_limit
-				.ensure_mul(GAS_TO_WEIGHT_MULTIPLIER)?,
+				.ensure_mul(GAS_TO_WEIGHT_MULTIPLIER)?
+				.ensure_add(25_000_000)?
+				.ensure_add(5_000_000)?,
 		)
 		.set_proof_size(DEFAULT_PROOF_SIZE.saturating_div(2));
 
@@ -261,9 +265,10 @@ where
 			// The currency in which we want to pay fees.
 			CurrencyPayment {
 				currency: Currency::AsCurrencyId(self.xcm_domain.fee_currency.clone()),
-				fee_amount: Some(
-					self.xcm_domain.fee_per_second * Into::<u128>::into(overall_weight.ref_time()),
-				),
+				fee_amount: Some(calculate_fee_amount(
+					overall_weight.ref_time(),
+					self.xcm_domain.fee_per_second,
+				)),
 			},
 			// The call to be executed in the destination chain.
 			ethereum_xcm_call,
@@ -278,6 +283,15 @@ where
 	}
 }
 
+/// Calculate the fee to be charged for the complete XCM message execution on
+/// the destination chain
+pub fn calculate_fee_amount(overall_weight_ref_time: u64, fee_per_second: u128) -> u128 {
+	fee_per_second
+		.saturating_mul(overall_weight_ref_time as u128)
+		.saturating_add(WEIGHT_REF_TIME_PER_SECOND as u128 - 1)
+		.saturating_div(WEIGHT_REF_TIME_PER_SECOND as u128)
+}
+
 pub(crate) fn get_encoded_ethereum_xcm_call<T>(
 	xcm_domain: XcmDomain<T::CurrencyId>,
 	msg: Vec<u8>,

runtime/integration-tests/src/liquidity_pools/pallet/development/tests/liquidity_pools.rs

@@ -782,6 +782,15 @@ fn transferring_invalid_tranche_tokens_should_fail() {
 	});
 }
 
+#[test]
+fn expected_fee_amount() {
+	// Roughly 0.15 GLMR
+	assert_eq!(
+		liquidity_pools_gateway_routers::calculate_fee_amount(15530000000, default_per_second(18)),
+		155548480000000000
+	)
+}
+
 #[test]
 fn add_currency() {
 	TestNet::reset();
@@ -814,10 +823,27 @@ fn add_currency() {
 			})
 		));
 
+		assert_eq!(
+			OrmlTokens::free_balance(
+				GLIMMER_CURRENCY_ID,
+				&<DevelopmentRuntime as pallet_liquidity_pools_gateway::Config>::Sender::get()
+			),
+			DEFAULT_BALANCE_GLMR
+		);
+
 		assert_ok!(LiquidityPools::add_currency(
 			RuntimeOrigin::signed(BOB.into()),
 			currency_id
 		));
+
+		assert_eq!(
+			OrmlTokens::free_balance(
+				GLIMMER_CURRENCY_ID,
+				&<DevelopmentRuntime as pallet_liquidity_pools_gateway::Config>::Sender::get()
+			),
+			/// Ensure it only charged roughly 0.15 GLMR for fees
+			DEFAULT_BALANCE_GLMR - 155548480000000000
+		);
 	});
 }
 
@@ -1681,14 +1707,17 @@ mod utils {
 	use liquidity_pools_gateway_routers::{
 		ethereum_xcm::EthereumXCMRouter, DomainRouter, XCMRouter, XcmTransactInfo,
 	};
+	use runtime_common::xcm_fees::native_per_second;
+	use sp_runtime::traits::{EnsureDiv, EnsureMul};
 
 	use super::*;
 	use crate::{
 		liquidity_pools::pallet::development::tests::register_ausd,
 		utils::{AUSD_CURRENCY_ID, GLIMMER_CURRENCY_ID, MOONBEAM_EVM_CHAIN_ID},
 	};
 
-	pub const DEFAULT_BALANCE_GLMR: Balance = 1_000_000_000_000;
+	// 10 GLMR (18 decimals)
+	pub const DEFAULT_BALANCE_GLMR: Balance = 10000000000000000000;
 	pub const DOMAIN_MOONBEAM: Domain = Domain::EVM(MOONBEAM_EVM_CHAIN_ID);
 	pub const DEFAULT_EVM_ADDRESS_MOONBEAM: [u8; 20] = [99; 20];
 	pub const DEFAULT_DOMAIN_ADDRESS_MOONBEAM: DomainAddress =
@@ -1748,7 +1777,7 @@ mod utils {
 					location: Box::new(xcm_domain_location),
 					ethereum_xcm_transact_call_index: BoundedVec::truncate_from(vec![38, 0]),
 					contract_address: H160::from(utils::DEFAULT_EVM_ADDRESS_MOONBEAM),
-					max_gas_limit: 700_000,
+					max_gas_limit: 500_000,
 					fee_currency: currency_id,
 					fee_per_second: default_per_second(18),
 				},
@@ -1805,7 +1834,7 @@ mod utils {
 		OrmlTokens::deposit(
 			GLIMMER_CURRENCY_ID,
 			&<DevelopmentRuntime as pallet_liquidity_pools_gateway::Config>::Sender::get(),
-			DEFAULT_BALANCE_GLMR * dollar(18),
+			DEFAULT_BALANCE_GLMR,
 		);
 
 		// Register AUSD in the asset registry which is the default pool currency in