Backport xcmpayment-fee tests from polkadot-fellows repo (paritytech#…

…5100)

# Description
This is continue of the work to backport
`emulated-integration-tests-common`, if you want to understand the full
context start with reading
[paritytech#4930](paritytech#4930)

cumulus/parachains/integration-tests/emulated/common/src/xcm_helpers.rs

@@ -69,3 +69,11 @@ pub fn non_fee_asset(assets: &Assets, fee_idx: usize) -> Option<(Location, u128)
 	};
 	Some((asset.id.0, asset_amount))
 }
+
+pub fn get_amount_from_versioned_assets(assets: VersionedAssets) -> u128 {
+	let latest_assets: Assets = assets.try_into().unwrap();
+	let Fungible(amount) = latest_assets.inner()[0].fun else {
+		unreachable!("asset is non-fungible");
+	};
+	amount
+}

cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-rococo/Cargo.toml

@@ -28,6 +28,7 @@ pallet-utility = { workspace = true }
 xcm = { workspace = true }
 pallet-xcm = { workspace = true }
 xcm-executor = { workspace = true }
+xcm-runtime-apis = { workspace = true, default-features = true }
 polkadot-runtime-common = { workspace = true, default-features = true }
 rococo-runtime-constants = { workspace = true, default-features = true }
 

cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-rococo/src/lib.rs

@@ -40,7 +40,9 @@ mod imports {
 			assert_expected_events, bx, Chain, Parachain as Para, RelayChain as Relay, Test,
 			TestArgs, TestContext, TestExt,
 		},
-		xcm_helpers::{non_fee_asset, xcm_transact_paid_execution},
+		xcm_helpers::{
+			get_amount_from_versioned_assets, non_fee_asset, xcm_transact_paid_execution,
+		},
 		ASSETS_PALLET_ID, RESERVABLE_ASSET_ID, XCM_V3,
 	};
 	pub use parachains_common::Balance;

cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-rococo/src/tests/mod.rs

@@ -21,3 +21,4 @@ mod set_xcm_versions;
 mod swap;
 mod teleport;
 mod treasury;
+mod xcm_fee_estimation;

cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-rococo/src/tests/xcm_fee_estimation.rs

@@ -0,0 +1,286 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Tests for XCM fee estimation in the runtime.
+
+use crate::imports::*;
+use frame_support::{
+	dispatch::RawOrigin,
+	sp_runtime::{traits::Dispatchable, DispatchResult},
+};
+use xcm_runtime_apis::{
+	dry_run::runtime_decl_for_dry_run_api::DryRunApiV1,
+	fees::runtime_decl_for_xcm_payment_api::XcmPaymentApiV1,
+};
+
+fn sender_assertions(test: ParaToParaThroughAHTest) {
+	type RuntimeEvent = <PenpalA as Chain>::RuntimeEvent;
+	PenpalA::assert_xcm_pallet_attempted_complete(None);
+
+	assert_expected_events!(
+		PenpalA,
+		vec![
+			RuntimeEvent::ForeignAssets(
+				pallet_assets::Event::Burned { asset_id, owner, balance }
+			) => {
+				asset_id: *asset_id == Location::new(1, []),
+				owner: *owner == test.sender.account_id,
+				balance: *balance == test.args.amount,
+			},
+		]
+	);
+}
+
+fn hop_assertions(test: ParaToParaThroughAHTest) {
+	type RuntimeEvent = <AssetHubRococo as Chain>::RuntimeEvent;
+	AssetHubRococo::assert_xcmp_queue_success(None);
+
+	assert_expected_events!(
+		AssetHubRococo,
+		vec![
+			RuntimeEvent::Balances(
+				pallet_balances::Event::Burned { amount, .. }
+			) => {
+				amount: *amount == test.args.amount,
+			},
+		]
+	);
+}
+
+fn receiver_assertions(test: ParaToParaThroughAHTest) {
+	type RuntimeEvent = <PenpalB as Chain>::RuntimeEvent;
+	PenpalB::assert_xcmp_queue_success(None);
+
+	assert_expected_events!(
+		PenpalB,
+		vec![
+			RuntimeEvent::ForeignAssets(
+				pallet_assets::Event::Issued { asset_id, owner, .. }
+			) => {
+				asset_id: *asset_id == Location::new(1, []),
+				owner: *owner == test.receiver.account_id,
+			},
+		]
+	);
+}
+
+fn transfer_assets_para_to_para_through_ah_dispatchable(
+	test: ParaToParaThroughAHTest,
+) -> DispatchResult {
+	let call = transfer_assets_para_to_para_through_ah_call(test.clone());
+	match call.dispatch(test.signed_origin) {
+		Ok(_) => Ok(()),
+		Err(error_with_post_info) => Err(error_with_post_info.error),
+	}
+}
+
+fn transfer_assets_para_to_para_through_ah_call(
+	test: ParaToParaThroughAHTest,
+) -> <PenpalA as Chain>::RuntimeCall {
+	type RuntimeCall = <PenpalA as Chain>::RuntimeCall;
+
+	let asset_hub_location: Location = PenpalB::sibling_location_of(AssetHubRococo::para_id());
+	let custom_xcm_on_dest = Xcm::<()>(vec![DepositAsset {
+		assets: Wild(AllCounted(test.args.assets.len() as u32)),
+		beneficiary: test.args.beneficiary,
+	}]);
+	RuntimeCall::PolkadotXcm(pallet_xcm::Call::transfer_assets_using_type_and_then {
+		dest: bx!(test.args.dest.into()),
+		assets: bx!(test.args.assets.clone().into()),
+		assets_transfer_type: bx!(TransferType::RemoteReserve(asset_hub_location.clone().into())),
+		remote_fees_id: bx!(VersionedAssetId::V4(AssetId(Location::new(1, [])))),
+		fees_transfer_type: bx!(TransferType::RemoteReserve(asset_hub_location.into())),
+		custom_xcm_on_dest: bx!(VersionedXcm::from(custom_xcm_on_dest)),
+		weight_limit: test.args.weight_limit,
+	})
+}
+
+/// We are able to dry-run and estimate the fees for a multi-hop XCM journey.
+/// Scenario: Alice on PenpalA has some DOTs and wants to send them to PenpalB.
+/// We want to know the fees using the `DryRunApi` and `XcmPaymentApi`.
+#[test]
+fn multi_hop_works() {
+	let destination = PenpalA::sibling_location_of(PenpalB::para_id());
+	let sender = PenpalASender::get();
+	let amount_to_send = 1_000_000_000_000;
+	let asset_owner = PenpalAssetOwner::get();
+	let assets: Assets = (Parent, amount_to_send).into();
+	let relay_native_asset_location = Location::parent();
+	let sender_as_seen_by_ah = AssetHubRococo::sibling_location_of(PenpalA::para_id());
+	let sov_of_sender_on_ah = AssetHubRococo::sovereign_account_id_of(sender_as_seen_by_ah.clone());
+
+	// fund Parachain's sender account
+	PenpalA::mint_foreign_asset(
+		<PenpalA as Chain>::RuntimeOrigin::signed(asset_owner.clone()),
+		relay_native_asset_location.clone(),
+		sender.clone(),
+		amount_to_send * 2,
+	);
+
+	// fund the Parachain Origin's SA on AssetHub with the native tokens held in reserve.
+	AssetHubRococo::fund_accounts(vec![(sov_of_sender_on_ah.clone(), amount_to_send * 2)]);
+
+	// Init values for Parachain Destination
+	let beneficiary_id = PenpalBReceiver::get();
+
+	let test_args = TestContext {
+		sender: PenpalASender::get(),     // Bob in PenpalB.
+		receiver: PenpalBReceiver::get(), // Alice.
+		args: TestArgs::new_para(
+			destination,
+			beneficiary_id.clone(),
+			amount_to_send,
+			assets,
+			None,
+			0,
+		),
+	};
+	let mut test = ParaToParaThroughAHTest::new(test_args);
+
+	// We get them from the PenpalA closure.
+	let mut delivery_fees_amount = 0;
+	let mut remote_message = VersionedXcm::V4(Xcm(Vec::new()));
+	<PenpalA as TestExt>::execute_with(|| {
+		type Runtime = <PenpalA as Chain>::Runtime;
+		type OriginCaller = <PenpalA as Chain>::OriginCaller;
+
+		let call = transfer_assets_para_to_para_through_ah_call(test.clone());
+		let origin = OriginCaller::system(RawOrigin::Signed(sender.clone()));
+		let result = Runtime::dry_run_call(origin, call).unwrap();
+		// We filter the result to get only the messages we are interested in.
+		let (destination_to_query, messages_to_query) = &result
+			.forwarded_xcms
+			.iter()
+			.find(|(destination, _)| {
+				*destination == VersionedLocation::V4(Location::new(1, [Parachain(1000)]))
+			})
+			.unwrap();
+		assert_eq!(messages_to_query.len(), 1);
+		remote_message = messages_to_query[0].clone();
+		let delivery_fees =
+			Runtime::query_delivery_fees(destination_to_query.clone(), remote_message.clone())
+				.unwrap();
+		delivery_fees_amount = get_amount_from_versioned_assets(delivery_fees);
+	});
+
+	// These are set in the AssetHub closure.
+	let mut intermediate_execution_fees = 0;
+	let mut intermediate_delivery_fees_amount = 0;
+	let mut intermediate_remote_message = VersionedXcm::V4(Xcm::<()>(Vec::new()));
+	<AssetHubRococo as TestExt>::execute_with(|| {
+		type Runtime = <AssetHubRococo as Chain>::Runtime;
+		type RuntimeCall = <AssetHubRococo as Chain>::RuntimeCall;
+
+		// First we get the execution fees.
+		let weight = Runtime::query_xcm_weight(remote_message.clone()).unwrap();
+		intermediate_execution_fees = Runtime::query_weight_to_asset_fee(
+			weight,
+			VersionedAssetId::V4(Location::new(1, []).into()),
+		)
+		.unwrap();
+
+		// We have to do this to turn `VersionedXcm<()>` into `VersionedXcm<RuntimeCall>`.
+		let xcm_program =
+			VersionedXcm::V4(Xcm::<RuntimeCall>::from(remote_message.clone().try_into().unwrap()));
+
+		// Now we get the delivery fees to the final destination.
+		let result =
+			Runtime::dry_run_xcm(sender_as_seen_by_ah.clone().into(), xcm_program).unwrap();
+		let (destination_to_query, messages_to_query) = &result
+			.forwarded_xcms
+			.iter()
+			.find(|(destination, _)| {
+				*destination == VersionedLocation::V4(Location::new(1, [Parachain(2001)]))
+			})
+			.unwrap();
+		// There's actually two messages here.
+		// One created when the message we sent from PenpalA arrived and was executed.
+		// The second one when we dry-run the xcm.
+		// We could've gotten the message from the queue without having to dry-run, but
+		// offchain applications would have to dry-run, so we do it here as well.
+		intermediate_remote_message = messages_to_query[0].clone();
+		let delivery_fees = Runtime::query_delivery_fees(
+			destination_to_query.clone(),
+			intermediate_remote_message.clone(),
+		)
+		.unwrap();
+		intermediate_delivery_fees_amount = get_amount_from_versioned_assets(delivery_fees);
+	});
+
+	// Get the final execution fees in the destination.
+	let mut final_execution_fees = 0;
+	<PenpalB as TestExt>::execute_with(|| {
+		type Runtime = <PenpalA as Chain>::Runtime;
+
+		let weight = Runtime::query_xcm_weight(intermediate_remote_message.clone()).unwrap();
+		final_execution_fees =
+			Runtime::query_weight_to_asset_fee(weight, VersionedAssetId::V4(Parent.into()))
+				.unwrap();
+	});
+
+	// Dry-running is done.
+	PenpalA::reset_ext();
+	AssetHubRococo::reset_ext();
+	PenpalB::reset_ext();
+
+	// Fund accounts again.
+	PenpalA::mint_foreign_asset(
+		<PenpalA as Chain>::RuntimeOrigin::signed(asset_owner),
+		relay_native_asset_location.clone(),
+		sender.clone(),
+		amount_to_send * 2,
+	);
+	AssetHubRococo::fund_accounts(vec![(sov_of_sender_on_ah, amount_to_send * 2)]);
+
+	// Actually run the extrinsic.
+	let sender_assets_before = PenpalA::execute_with(|| {
+		type ForeignAssets = <PenpalA as PenpalAPallet>::ForeignAssets;
+		<ForeignAssets as Inspect<_>>::balance(relay_native_asset_location.clone(), &sender)
+	});
+	let receiver_assets_before = PenpalB::execute_with(|| {
+		type ForeignAssets = <PenpalB as PenpalBPallet>::ForeignAssets;
+		<ForeignAssets as Inspect<_>>::balance(relay_native_asset_location.clone(), &beneficiary_id)
+	});
+
+	test.set_assertion::<PenpalA>(sender_assertions);
+	test.set_assertion::<AssetHubRococo>(hop_assertions);
+	test.set_assertion::<PenpalB>(receiver_assertions);
+	test.set_dispatchable::<PenpalA>(transfer_assets_para_to_para_through_ah_dispatchable);
+	test.assert();
+
+	let sender_assets_after = PenpalA::execute_with(|| {
+		type ForeignAssets = <PenpalA as PenpalAPallet>::ForeignAssets;
+		<ForeignAssets as Inspect<_>>::balance(relay_native_asset_location.clone(), &sender)
+	});
+	let receiver_assets_after = PenpalB::execute_with(|| {
+		type ForeignAssets = <PenpalB as PenpalBPallet>::ForeignAssets;
+		<ForeignAssets as Inspect<_>>::balance(relay_native_asset_location, &beneficiary_id)
+	});
+
+	// We know the exact fees on every hop.
+	assert_eq!(
+		sender_assets_after,
+		sender_assets_before - amount_to_send - delivery_fees_amount /* This is charged directly
+		                                                              * from the sender's
+		                                                              * account. */
+	);
+	assert_eq!(
+		receiver_assets_after,
+		receiver_assets_before + amount_to_send -
+			intermediate_execution_fees -
+			intermediate_delivery_fees_amount -
+			final_execution_fees
+	);
+}

cumulus/parachains/integration-tests/emulated/tests/assets/asset-hub-westend/src/lib.rs

@@ -40,7 +40,9 @@ mod imports {
 			assert_expected_events, bx, Chain, Parachain as Para, RelayChain as Relay, Test,
 			TestArgs, TestContext, TestExt,
 		},
-		xcm_helpers::{non_fee_asset, xcm_transact_paid_execution},
+		xcm_helpers::{
+			get_amount_from_versioned_assets, non_fee_asset, xcm_transact_paid_execution,
+		},
 		ASSETS_PALLET_ID, RESERVABLE_ASSET_ID, XCM_V3,
 	};
 	pub use parachains_common::{AccountId, Balance};