PayOverXcm: Add test skeleton

xcm/pallet-xcm/src/lib.rs

@@ -1135,7 +1135,7 @@ impl<T: Config> QueryHandler for Pallet<T> {
 	/// Attempt to create a new query ID and register it as a query that is yet to respond.
 	fn new_query(
 		responder: impl Into<MultiLocation>,
-		timeout: T::BlockNumber,
+		timeout: Self::BlockNumber,
 		match_querier: impl Into<MultiLocation>,
 	) -> Self::QueryId {
 		Self::do_new_query(responder, None, timeout, match_querier).into()

xcm/xcm-builder/src/tests/mock.rs

@@ -42,7 +42,7 @@ pub use sp_std::{
 	marker::PhantomData,
 };
 pub use xcm::latest::{prelude::*, Weight};
-use xcm_executor::traits::Properties;
+use xcm_executor::traits::{Properties, QueryHandler, QueryResponseStatus};
 pub use xcm_executor::{
 	traits::{
 		AssetExchange, AssetLock, CheckSuspension, ConvertOrigin, Enact, ExportXcm, FeeManager,
@@ -410,6 +410,63 @@ pub fn response(query_id: u64) -> Option<Response> {
 	})
 }
 
+// TODO: Add counter for query ids
+// TODO: Add more information in QUERIES
+pub struct TestQueryHandler<T, BlockNumber>(core::marker::PhantomData<(T, BlockNumber)>);
+impl<T: Config, BlockNumber: sp_runtime::traits::Zero> QueryHandler
+	for TestQueryHandler<T, BlockNumber>
+{
+	type QueryId = u64;
+	type BlockNumber = BlockNumber;
+	type Error = XcmError;
+	type UniversalLocation = T::UniversalLocation;
+
+	fn new_query(
+		responder: impl Into<MultiLocation>,
+		timeout: Self::BlockNumber,
+		match_querier: impl Into<MultiLocation>,
+	) -> Self::QueryId {
+		let query_id = 1;
+		expect_response(query_id, responder.into());
+		query_id
+	}
+
+	fn report_outcome(
+		message: &mut Xcm<()>,
+		responder: impl Into<MultiLocation>,
+		timeout: Self::BlockNumber,
+	) -> Result<Self::QueryId, Self::Error> {
+		let responder = responder.into();
+		let destination = Self::UniversalLocation::get()
+			.invert_target(&responder)
+			.map_err(|()| XcmError::LocationNotInvertible)?;
+		let query_id = Self::new_query(responder, timeout, Here);
+		let response_info = QueryResponseInfo { destination, query_id, max_weight: Weight::zero() };
+		let report_error = Xcm(vec![ReportError(response_info)]);
+		message.0.insert(0, SetAppendix(report_error));
+		Ok(query_id)
+	}
+
+	fn take_response(query_id: Self::QueryId) -> QueryResponseStatus<Self::BlockNumber> {
+		QUERIES
+			.with(|q| {
+				q.borrow().get(&query_id).and_then(|v| match v {
+					ResponseSlot::Received(r) => Some(QueryResponseStatus::Ready {
+						response: r.clone(),
+						at: Self::BlockNumber::zero(),
+					}),
+					_ => Some(QueryResponseStatus::NotFound),
+				})
+			})
+			.unwrap_or(QueryResponseStatus::NotFound)
+	}
+
+	// #[cfg(feature = "runtime-benchmarks")]
+	// fn expect_response(id: Self::QueryId, response: xcm::latest::Result) {
+	// 	// Unneeded since this is only test
+	// }
+}
+
 parameter_types! {
 	pub static ExecutorUniversalLocation: InteriorMultiLocation
 		= (ByGenesis([0; 32]), Parachain(42)).into();

xcm/xcm-builder/src/tests/mod.rs

@@ -34,6 +34,7 @@ mod bridging;
 mod expecting;
 mod locking;
 mod origins;
+mod pay;
 mod querying;
 mod transacting;
 mod version_subscriptions;

xcm/xcm-builder/src/tests/pay.rs

@@ -0,0 +1,69 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use super::*;
+use frame_support::{assert_ok, traits::tokens::Pay};
+use sp_runtime::traits::Convert;
+
+type BlockNumber = u64;
+type AccountId = u64;
+
+parameter_types! {
+	pub Interior: InteriorMultiLocation = AccountIndex64 { index: 3u64, network: None }.into();
+	pub Timeout: BlockNumber = 5; // 5 blocks
+	pub Beneficiary: AccountId = 5;
+}
+
+#[derive(Encode, Decode, Clone, Copy, PartialEq, Eq)]
+pub struct AssetKind {
+	destination: xcm::latest::MultiLocation,
+	asset_id: xcm::latest::AssetId,
+}
+
+pub struct LocatableAssetKindConverter;
+impl sp_runtime::traits::Convert<AssetKind, LocatableAssetId> for LocatableAssetKindConverter {
+	fn convert(value: AssetKind) -> LocatableAssetId {
+		LocatableAssetId { asset_id: value.asset_id, location: value.destination }
+	}
+}
+
+pub struct AliasesIntoAccountIndex64;
+impl<'a> sp_runtime::traits::Convert<&'a AccountId, MultiLocation> for AliasesIntoAccountIndex64 {
+	fn convert(who: &AccountId) -> MultiLocation {
+		AccountIndex64 { network: None, index: who.clone().into() }.into()
+	}
+}
+
+#[test]
+fn pay_over_xcm_works() {
+	AllowExplicitUnpaidFrom::set(vec![X1(Parachain(1)).into()]);
+	add_asset(AliasesIntoAccountIndex64::convert(&3u64), (Here, 1000u128));
+	let who = 5u64;
+	let asset_kind =
+		AssetKind { destination: (Parent, Parachain(2)).into(), asset_id: Here.into() };
+	let amount = 1000u128;
+	assert_ok!(PayOverXcm::<
+		Interior,
+		TestMessageSender,
+		TestQueryHandler<TestConfig, BlockNumber>,
+		Timeout,
+		AccountId,
+		AssetKind,
+		LocatableAssetKindConverter,
+		AliasesIntoAccountIndex64,
+	>::pay(&who, asset_kind, amount));
+	dbg!(&sent_xcm());
+}

xcm/xcm-builder/src/tests/pay/mod.rs

@@ -0,0 +1,25 @@
+mod pay;
+mod salary;
+
+/// Type representing both a location and an asset that is held at that location.
+/// The id of the held asset is relative to the location where it is being held.
+#[derive(Encode, Decode, Clone, Copy, PartialEq, Eq)]
+pub struct AssetKind {
+	destination: MultiLocation,
+	asset_id: AssetId,
+}
+
+pub struct LocatableAssetKindConverter;
+impl sp_runtime::traits::Convert<AssetKind, LocatableAssetId> for LocatableAssetKindConverter {
+	fn convert(value: AssetKind) -> LocatableAssetId {
+		LocatableAssetId { asset_id: value.asset_id, location: value.destination }
+	}
+}
+
+/// Simple converter to turn a u64 into a MultiLocation using the AccountIndex64 junction and no parents
+pub struct AliasesIntoAccountIndex64;
+impl<'a> sp_runtime::traits::Convert<&'a AccountId, MultiLocation> for AliasesIntoAccountIndex64 {
+	fn convert(who: &AccountId) -> MultiLocation {
+		AccountIndex64 { network: None, index: who.clone().into() }.into()
+	}
+}

xcm/xcm-builder/src/tests/pay/pay.rs

@@ -0,0 +1,107 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Tests for making sure `PayOverXcm::pay` generates the correct message and sends it to the correct destination
+
+use super::{super::*, *};
+use frame_support::{assert_ok, traits::tokens::Pay};
+
+type BlockNumber = u64;
+type AccountId = u64;
+
+parameter_types! {
+	pub InteriorAccount: InteriorMultiLocation = AccountIndex64 { index: 3u64, network: None }.into();
+	pub InteriorBody: InteriorMultiLocation = Plurality { id: BodyId::Treasury, part: BodyPart::Voice }.into();
+	pub Timeout: BlockNumber = 5; // 5 blocks
+	pub Beneficiary: AccountId = 5;
+}
+
+/// Scenario:
+/// Account #3 on the local chain, Parachain(42), controls an amount of funds on Parachain(2).
+/// PayOverXcm::pay creates the correct message for account #3 to pay another account, account #5, on Parachain(2), remotely, in its native token.
+#[test]
+fn pay_over_xcm_works() {
+	let who = 5u64;
+	let asset_kind =
+		AssetKind { destination: (Parent, Parachain(2)).into(), asset_id: Here.into() };
+	let amount = 1000u128;
+
+	assert_ok!(PayOverXcm::<
+		InteriorAccount,
+		TestMessageSender,
+		TestQueryHandler<TestConfig, BlockNumber>,
+		Timeout,
+		AccountId,
+		AssetKind,
+		LocatableAssetKindConverter,
+		AliasesIntoAccountIndex64,
+	>::pay(&who, asset_kind, amount));
+
+	let expected_message = Xcm(vec![
+		UnpaidExecution { weight_limit: Unlimited, check_origin: None },
+		SetAppendix(Xcm(vec![ReportError(QueryResponseInfo {
+			destination: (Parent, Parachain(42)).into(),
+			query_id: 1,
+			max_weight: Weight::zero(),
+		})])),
+		DescendOrigin(AccountIndex64 { index: 3, network: None }.into()),
+		TransferAsset {
+			assets: (Here, 1000u128).into(),
+			beneficiary: AccountIndex64 { index: 5, network: None }.into(),
+		},
+	]);
+
+	let expected_hash = fake_message_hash(&expected_message);
+	assert_eq!(sent_xcm(), vec![((Parent, Parachain(2)).into(), expected_message, expected_hash)]);
+}
+
+/// Scenario:
+/// A pluralistic body, a Treasury, on the local chain, Parachain(42), controls an amount of funds on Parachain(2).
+/// PayOverXcm::pay creates the correct message for the treasury to pay another account, account #7, on Parachain(2), remotely, in the relay's token.
+#[test]
+fn pay_over_xcm_governance_body() {
+	let who = 7u64;
+	let asset_kind =
+		AssetKind { destination: (Parent, Parachain(2)).into(), asset_id: Parent.into() };
+	let amount = 500u128;
+
+	assert_ok!(PayOverXcm::<
+		InteriorBody,
+		TestMessageSender,
+		TestQueryHandler<TestConfig, BlockNumber>,
+		Timeout,
+		AccountId,
+		AssetKind,
+		LocatableAssetKindConverter,
+		AliasesIntoAccountIndex64,
+	>::pay(&who, asset_kind, amount));
+
+	let expected_message = Xcm(vec![
+		UnpaidExecution { weight_limit: Unlimited, check_origin: None },
+		SetAppendix(Xcm(vec![ReportError(QueryResponseInfo {
+			destination: (Parent, Parachain(42)).into(),
+			query_id: 1,
+			max_weight: Weight::zero(),
+		})])),
+		DescendOrigin(Plurality { id: BodyId::Treasury, part: BodyPart::Voice }.into()),
+		TransferAsset {
+			assets: (Parent, 500u128).into(),
+			beneficiary: AccountIndex64 { index: 7, network: None }.into(),
+		},
+	]);
+	let expected_hash = fake_message_hash(&expected_message);
+	assert_eq!(sent_xcm(), vec![((Parent, Parachain(2)).into(), expected_message, expected_hash)]);
+}