XCM WeightTrader: Swap Fee Asset for Native Asset (#1845)

Implements an XCM executor `WeightTrader`, facilitating fee payments in
any asset that can be exchanged for a native asset.

A few constraints need to be observed:
- `buy_weight` and `refund` operations must be atomic, as another weight
trader implementation might be attempted in case of failure.
- swap credit must be utilized since there isn’t an account to which an
asset of some class can be deposited with a guarantee to meet the
existential deposit requirement. Also, operating with credits enhances
the efficiency of the weight trader -
#1677

related PRs:
- (depends) #2031
- (depends) #1677
- (caused) #1847
- (caused) #1876

// DONE: impl `OnUnbalanced` for a `fungible/s` credit
// DONE: make the trader free from a concept of a native currency and
drop few fallible conversions. related issue -
#1842
// DONE: tests

---------

Co-authored-by: joe petrowski <[email protected]>
Co-authored-by: Liam Aharon <[email protected]>

Author: 3 people

Cargo.lock

@@ -27,78 +27,3 @@ fn send_transact_as_superuser_from_relay_to_system_para_works() {
 		Some(Weight::from_parts(1_019_445_000, 200_000)),
 	)
 }
-
-/// Parachain should be able to send XCM paying its fee with sufficient asset
-/// in the System Parachain
-#[test]
-fn send_xcm_from_para_to_system_para_paying_fee_with_assets_works() {
-	let para_sovereign_account = AssetHubRococo::sovereign_account_id_of(
-		AssetHubRococo::sibling_location_of(PenpalA::para_id()),
-	);
-
-	// Force create and mint assets for Parachain's sovereign account
-	AssetHubRococo::force_create_and_mint_asset(
-		ASSET_ID,
-		ASSET_MIN_BALANCE,
-		true,
-		para_sovereign_account.clone(),
-		Some(Weight::from_parts(1_019_445_000, 200_000)),
-		ASSET_MIN_BALANCE * 1000000000,
-	);
-
-	// We just need a call that can pass the `SafeCallFilter`
-	// Call values are not relevant
-	let call = AssetHubRococo::force_create_asset_call(
-		ASSET_ID,
-		para_sovereign_account.clone(),
-		true,
-		ASSET_MIN_BALANCE,
-	);
-
-	let origin_kind = OriginKind::SovereignAccount;
-	let fee_amount = ASSET_MIN_BALANCE * 1000000;
-	let native_asset =
-		(X2(PalletInstance(ASSETS_PALLET_ID), GeneralIndex(ASSET_ID.into())), fee_amount).into();
-
-	let root_origin = <PenpalA as Chain>::RuntimeOrigin::root();
-	let system_para_destination = PenpalA::sibling_location_of(AssetHubRococo::para_id()).into();
-	let xcm = xcm_transact_paid_execution(
-		call,
-		origin_kind,
-		native_asset,
-		para_sovereign_account.clone(),
-	);
-
-	PenpalA::execute_with(|| {
-		assert_ok!(<PenpalA as PenpalAPallet>::PolkadotXcm::send(
-			root_origin,
-			bx!(system_para_destination),
-			bx!(xcm),
-		));
-
-		PenpalA::assert_xcm_pallet_sent();
-	});
-
-	AssetHubRococo::execute_with(|| {
-		type RuntimeEvent = <AssetHubRococo as Chain>::RuntimeEvent;
-
-		AssetHubRococo::assert_xcmp_queue_success(Some(Weight::from_parts(
-			15_594_564_000,
-			562_893,
-		)));
-
-		assert_expected_events!(
-			AssetHubRococo,
-			vec![
-				RuntimeEvent::Assets(pallet_assets::Event::Burned { asset_id, owner, balance }) => {
-					asset_id: *asset_id == ASSET_ID,
-					owner: *owner == para_sovereign_account,
-					balance: *balance == fee_amount,
-				},
-				RuntimeEvent::Assets(pallet_assets::Event::Issued { asset_id, .. }) => {
-					asset_id: *asset_id == ASSET_ID,
-				},
-			]
-		);
-	});
-}

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

@@ -270,3 +270,130 @@ fn cannot_create_pool_from_pool_assets() {
 		);
 	});
 }
+
+#[test]
+fn pay_xcm_fee_with_some_asset_swapped_for_native() {
+	let asset_native = asset_hub_rococo_runtime::xcm_config::TokenLocation::get();
+	let asset_one = MultiLocation {
+		parents: 0,
+		interior: X2(PalletInstance(ASSETS_PALLET_ID), GeneralIndex(ASSET_ID.into())),
+	};
+	let penpal = AssetHubRococo::sovereign_account_id_of(AssetHubRococo::sibling_location_of(
+		PenpalA::para_id(),
+	));
+
+	AssetHubRococo::execute_with(|| {
+		type RuntimeEvent = <AssetHubRococo as Chain>::RuntimeEvent;
+
+		// set up pool with ASSET_ID <> NATIVE pair
+		assert_ok!(<AssetHubRococo as AssetHubRococoPallet>::Assets::create(
+			<AssetHubRococo as Chain>::RuntimeOrigin::signed(AssetHubRococoSender::get()),
+			ASSET_ID.into(),
+			AssetHubRococoSender::get().into(),
+			ASSET_MIN_BALANCE,
+		));
+		assert!(<AssetHubRococo as AssetHubRococoPallet>::Assets::asset_exists(ASSET_ID));
+
+		assert_ok!(<AssetHubRococo as AssetHubRococoPallet>::Assets::mint(
+			<AssetHubRococo as Chain>::RuntimeOrigin::signed(AssetHubRococoSender::get()),
+			ASSET_ID.into(),
+			AssetHubRococoSender::get().into(),
+			3_000_000_000_000,
+		));
+
+		assert_ok!(<AssetHubRococo as AssetHubRococoPallet>::AssetConversion::create_pool(
+			<AssetHubRococo as Chain>::RuntimeOrigin::signed(AssetHubRococoSender::get()),
+			Box::new(asset_native),
+			Box::new(asset_one),
+		));
+
+		assert_expected_events!(
+			AssetHubRococo,
+			vec![
+				RuntimeEvent::AssetConversion(pallet_asset_conversion::Event::PoolCreated { .. }) => {},
+			]
+		);
+
+		assert_ok!(<AssetHubRococo as AssetHubRococoPallet>::AssetConversion::add_liquidity(
+			<AssetHubRococo as Chain>::RuntimeOrigin::signed(AssetHubRococoSender::get()),
+			Box::new(asset_native),
+			Box::new(asset_one),
+			1_000_000_000_000,
+			2_000_000_000_000,
+			0,
+			0,
+			AssetHubRococoSender::get().into()
+		));
+
+		assert_expected_events!(
+			AssetHubRococo,
+			vec![
+				RuntimeEvent::AssetConversion(pallet_asset_conversion::Event::LiquidityAdded {lp_token_minted, .. }) => { lp_token_minted: *lp_token_minted == 1414213562273, },
+			]
+		);
+
+		// ensure `penpal` sovereign account has no native tokens and mint some `ASSET_ID`
+		assert_eq!(
+			<AssetHubRococo as AssetHubRococoPallet>::Balances::free_balance(penpal.clone()),
+			0
+		);
+
+		assert_ok!(<AssetHubRococo as AssetHubRococoPallet>::Assets::touch_other(
+			<AssetHubRococo as Chain>::RuntimeOrigin::signed(AssetHubRococoSender::get()),
+			ASSET_ID.into(),
+			penpal.clone().into(),
+		));
+
+		assert_ok!(<AssetHubRococo as AssetHubRococoPallet>::Assets::mint(
+			<AssetHubRococo as Chain>::RuntimeOrigin::signed(AssetHubRococoSender::get()),
+			ASSET_ID.into(),
+			penpal.clone().into(),
+			10_000_000_000_000,
+		));
+	});
+
+	PenpalA::execute_with(|| {
+		// send xcm transact from `penpal` account which as only `ASSET_ID` tokens on
+		// `AssetHubRococo`
+		let call = AssetHubRococo::force_create_asset_call(
+			ASSET_ID + 1000,
+			penpal.clone(),
+			true,
+			ASSET_MIN_BALANCE,
+		);
+
+		let penpal_root = <PenpalA as Chain>::RuntimeOrigin::root();
+		let fee_amount = 4_000_000_000_000u128;
+		let asset_one =
+			(X2(PalletInstance(ASSETS_PALLET_ID), GeneralIndex(ASSET_ID.into())), fee_amount)
+				.into();
+		let asset_hub_location = PenpalA::sibling_location_of(AssetHubRococo::para_id()).into();
+		let xcm = xcm_transact_paid_execution(
+			call,
+			OriginKind::SovereignAccount,
+			asset_one,
+			penpal.clone(),
+		);
+
+		assert_ok!(<PenpalA as PenpalAPallet>::PolkadotXcm::send(
+			penpal_root,
+			bx!(asset_hub_location),
+			bx!(xcm),
+		));
+
+		PenpalA::assert_xcm_pallet_sent();
+	});
+
+	AssetHubRococo::execute_with(|| {
+		type RuntimeEvent = <AssetHubRococo as Chain>::RuntimeEvent;
+
+		AssetHubRococo::assert_xcmp_queue_success(None);
+		assert_expected_events!(
+			AssetHubRococo,
+			vec![
+				RuntimeEvent::AssetConversion(pallet_asset_conversion::Event::SwapCreditExecuted { .. },) => {},
+				RuntimeEvent::MessageQueue(pallet_message_queue::Event::Processed { success: true,.. }) => {},
+			]
+		);
+	});
+}

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

@@ -27,78 +27,3 @@ fn send_transact_as_superuser_from_relay_to_system_para_works() {
 		Some(Weight::from_parts(1_019_445_000, 200_000)),
 	)
 }
-
-/// Parachain should be able to send XCM paying its fee with sufficient asset
-/// in the System Parachain
-#[test]
-fn send_xcm_from_para_to_system_para_paying_fee_with_assets_works() {
-	let para_sovereign_account = AssetHubWestend::sovereign_account_id_of(
-		AssetHubWestend::sibling_location_of(PenpalB::para_id()),
-	);
-
-	// Force create and mint assets for Parachain's sovereign account
-	AssetHubWestend::force_create_and_mint_asset(
-		ASSET_ID,
-		ASSET_MIN_BALANCE,
-		true,
-		para_sovereign_account.clone(),
-		Some(Weight::from_parts(1_019_445_000, 200_000)),
-		ASSET_MIN_BALANCE * 1000000000,
-	);
-
-	// We just need a call that can pass the `SafeCallFilter`
-	// Call values are not relevant
-	let call = AssetHubWestend::force_create_asset_call(
-		ASSET_ID,
-		para_sovereign_account.clone(),
-		true,
-		ASSET_MIN_BALANCE,
-	);
-
-	let origin_kind = OriginKind::SovereignAccount;
-	let fee_amount = ASSET_MIN_BALANCE * 1000000;
-	let native_asset =
-		(X2(PalletInstance(ASSETS_PALLET_ID), GeneralIndex(ASSET_ID.into())), fee_amount).into();
-
-	let root_origin = <PenpalB as Chain>::RuntimeOrigin::root();
-	let system_para_destination = PenpalB::sibling_location_of(AssetHubWestend::para_id()).into();
-	let xcm = xcm_transact_paid_execution(
-		call,
-		origin_kind,
-		native_asset,
-		para_sovereign_account.clone(),
-	);
-
-	PenpalB::execute_with(|| {
-		assert_ok!(<PenpalB as PenpalBPallet>::PolkadotXcm::send(
-			root_origin,
-			bx!(system_para_destination),
-			bx!(xcm),
-		));
-
-		PenpalB::assert_xcm_pallet_sent();
-	});
-
-	AssetHubWestend::execute_with(|| {
-		type RuntimeEvent = <AssetHubWestend as Chain>::RuntimeEvent;
-
-		AssetHubWestend::assert_xcmp_queue_success(Some(Weight::from_parts(
-			16_290_336_000,
-			562_893,
-		)));
-
-		assert_expected_events!(
-			AssetHubWestend,
-			vec![
-				RuntimeEvent::Assets(pallet_assets::Event::Burned { asset_id, owner, balance }) => {
-					asset_id: *asset_id == ASSET_ID,
-					owner: *owner == para_sovereign_account,
-					balance: *balance == fee_amount,
-				},
-				RuntimeEvent::Assets(pallet_assets::Event::Issued { asset_id, .. }) => {
-					asset_id: *asset_id == ASSET_ID,
-				},
-			]
-		);
-	});
-}