parachains_runtimes_test_utils/

lib.rs

// 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.

use core::marker::PhantomData;

use codec::{Decode, DecodeLimit};
use cumulus_primitives_core::{
	relay_chain::Slot, AbridgedHrmpChannel, ParaId, PersistedValidationData,
};
use cumulus_primitives_parachain_inherent::ParachainInherentData;
use cumulus_test_relay_sproof_builder::RelayStateSproofBuilder;
use frame_support::{
	dispatch::{DispatchResult, GetDispatchInfo, RawOrigin},
	inherent::{InherentData, ProvideInherent},
	pallet_prelude::Get,
	traits::{OnFinalize, OnInitialize, OriginTrait, UnfilteredDispatchable},
	weights::Weight,
};
use frame_system::pallet_prelude::{BlockNumberFor, HeaderFor};
use polkadot_parachain_primitives::primitives::{
	HeadData, HrmpChannelId, RelayChainBlockNumber, XcmpMessageFormat,
};
use sp_consensus_aura::{SlotDuration, AURA_ENGINE_ID};
use sp_core::{Encode, U256};
use sp_runtime::{
	traits::{Dispatchable, Header},
	BuildStorage, Digest, DigestItem, DispatchError, Either, SaturatedConversion,
};
use xcm::{
	latest::{Asset, Location, XcmContext, XcmHash},
	prelude::*,
	VersionedXcm, MAX_XCM_DECODE_DEPTH,
};
use xcm_executor::{traits::TransactAsset, AssetsInHolding};

pub mod test_cases;

pub type BalanceOf<Runtime> = <Runtime as pallet_balances::Config>::Balance;
pub type AccountIdOf<Runtime> = <Runtime as frame_system::Config>::AccountId;
pub type RuntimeCallOf<Runtime> = <Runtime as frame_system::Config>::RuntimeCall;
pub type RuntimeOriginOf<Runtime> = <Runtime as frame_system::Config>::RuntimeOrigin;
pub type ValidatorIdOf<Runtime> = <Runtime as pallet_session::Config>::ValidatorId;
pub type SessionKeysOf<Runtime> = <Runtime as pallet_session::Config>::Keys;

pub struct CollatorSessionKey<
	Runtime: frame_system::Config + pallet_balances::Config + pallet_session::Config,
> {
	collator: AccountIdOf<Runtime>,
	validator: ValidatorIdOf<Runtime>,
	key: SessionKeysOf<Runtime>,
}

pub struct CollatorSessionKeys<
	Runtime: frame_system::Config + pallet_balances::Config + pallet_session::Config,
> {
	items: Vec<CollatorSessionKey<Runtime>>,
}

impl<Runtime: frame_system::Config + pallet_balances::Config + pallet_session::Config>
	CollatorSessionKey<Runtime>
{
	pub fn new(
		collator: AccountIdOf<Runtime>,
		validator: ValidatorIdOf<Runtime>,
		key: SessionKeysOf<Runtime>,
	) -> Self {
		Self { collator, validator, key }
	}
}

impl<Runtime: frame_system::Config + pallet_balances::Config + pallet_session::Config> Default
	for CollatorSessionKeys<Runtime>
{
	fn default() -> Self {
		Self { items: vec![] }
	}
}

impl<Runtime: frame_system::Config + pallet_balances::Config + pallet_session::Config>
	CollatorSessionKeys<Runtime>
{
	pub fn new(
		collator: AccountIdOf<Runtime>,
		validator: ValidatorIdOf<Runtime>,
		key: SessionKeysOf<Runtime>,
	) -> Self {
		Self { items: vec![CollatorSessionKey::new(collator, validator, key)] }
	}

	pub fn add(mut self, item: CollatorSessionKey<Runtime>) -> Self {
		self.items.push(item);
		self
	}

	pub fn collators(&self) -> Vec<AccountIdOf<Runtime>> {
		self.items.iter().map(|item| item.collator.clone()).collect::<Vec<_>>()
	}

	pub fn session_keys(
		&self,
	) -> Vec<(AccountIdOf<Runtime>, ValidatorIdOf<Runtime>, SessionKeysOf<Runtime>)> {
		self.items
			.iter()
			.map(|item| (item.collator.clone(), item.validator.clone(), item.key.clone()))
			.collect::<Vec<_>>()
	}
}

pub struct SlotDurations {
	pub relay: SlotDuration,
	pub para: SlotDuration,
}

/// A set of traits for a minimal parachain runtime, that may be used in conjunction with the
/// `ExtBuilder` and the `RuntimeHelper`.
pub trait BasicParachainRuntime:
	frame_system::Config
	+ pallet_balances::Config
	+ pallet_session::Config
	+ pallet_xcm::Config
	+ parachain_info::Config
	+ pallet_collator_selection::Config
	+ cumulus_pallet_parachain_system::Config
	+ pallet_timestamp::Config
{
}

impl<T> BasicParachainRuntime for T
where
	T: frame_system::Config
		+ pallet_balances::Config
		+ pallet_session::Config
		+ pallet_xcm::Config
		+ parachain_info::Config
		+ pallet_collator_selection::Config
		+ cumulus_pallet_parachain_system::Config
		+ pallet_timestamp::Config,
	ValidatorIdOf<T>: From<AccountIdOf<T>>,
{
}

/// Basic builder based on balances, collators and pallet_session.
pub struct ExtBuilder<Runtime: BasicParachainRuntime> {
	// endowed accounts with balances
	balances: Vec<(AccountIdOf<Runtime>, BalanceOf<Runtime>)>,
	// collators to test block prod
	collators: Vec<AccountIdOf<Runtime>>,
	// keys added to pallet session
	keys: Vec<(AccountIdOf<Runtime>, ValidatorIdOf<Runtime>, SessionKeysOf<Runtime>)>,
	// safe XCM version for pallet_xcm
	safe_xcm_version: Option<XcmVersion>,
	// para id
	para_id: Option<ParaId>,
	_runtime: PhantomData<Runtime>,
}

impl<Runtime: BasicParachainRuntime> Default for ExtBuilder<Runtime> {
	fn default() -> ExtBuilder<Runtime> {
		ExtBuilder {
			balances: vec![],
			collators: vec![],
			keys: vec![],
			safe_xcm_version: None,
			para_id: None,
			_runtime: PhantomData,
		}
	}
}

impl<Runtime: BasicParachainRuntime> ExtBuilder<Runtime> {
	pub fn with_balances(
		mut self,
		balances: Vec<(AccountIdOf<Runtime>, BalanceOf<Runtime>)>,
	) -> Self {
		self.balances = balances;
		self
	}
	pub fn with_collators(mut self, collators: Vec<AccountIdOf<Runtime>>) -> Self {
		self.collators = collators;
		self
	}

	pub fn with_session_keys(
		mut self,
		keys: Vec<(AccountIdOf<Runtime>, ValidatorIdOf<Runtime>, SessionKeysOf<Runtime>)>,
	) -> Self {
		self.keys = keys;
		self
	}

	pub fn with_tracing(self) -> Self {
		sp_tracing::try_init_simple();
		self
	}

	pub fn with_safe_xcm_version(mut self, safe_xcm_version: XcmVersion) -> Self {
		self.safe_xcm_version = Some(safe_xcm_version);
		self
	}

	pub fn with_para_id(mut self, para_id: ParaId) -> Self {
		self.para_id = Some(para_id);
		self
	}

	pub fn build(self) -> sp_io::TestExternalities {
		let mut t = frame_system::GenesisConfig::<Runtime>::default().build_storage().unwrap();

		pallet_xcm::GenesisConfig::<Runtime> {
			safe_xcm_version: self.safe_xcm_version,
			..Default::default()
		}
		.assimilate_storage(&mut t)
		.unwrap();

		if let Some(para_id) = self.para_id {
			parachain_info::GenesisConfig::<Runtime> {
				parachain_id: para_id,
				..Default::default()
			}
			.assimilate_storage(&mut t)
			.unwrap();
		}

		pallet_balances::GenesisConfig::<Runtime> { balances: self.balances, ..Default::default() }
			.assimilate_storage(&mut t)
			.unwrap();

		pallet_collator_selection::GenesisConfig::<Runtime> {
			invulnerables: self.collators.clone(),
			candidacy_bond: Default::default(),
			desired_candidates: Default::default(),
		}
		.assimilate_storage(&mut t)
		.unwrap();

		pallet_session::GenesisConfig::<Runtime> { keys: self.keys, ..Default::default() }
			.assimilate_storage(&mut t)
			.unwrap();

		let mut ext = sp_io::TestExternalities::new(t);

		ext.execute_with(|| {
			frame_system::Pallet::<Runtime>::set_block_number(1u32.into());
		});

		ext
	}
}

pub struct RuntimeHelper<Runtime, AllPalletsWithoutSystem>(
	PhantomData<(Runtime, AllPalletsWithoutSystem)>,
);
/// Utility function that advances the chain to the desired block number.
/// If an author is provided, that author information is injected to all the blocks in the meantime.
impl<
		Runtime: frame_system::Config + cumulus_pallet_parachain_system::Config + pallet_timestamp::Config,
		AllPalletsWithoutSystem,
	> RuntimeHelper<Runtime, AllPalletsWithoutSystem>
where
	AccountIdOf<Runtime>:
		Into<<<Runtime as frame_system::Config>::RuntimeOrigin as OriginTrait>::AccountId>,
	AllPalletsWithoutSystem:
		OnInitialize<BlockNumberFor<Runtime>> + OnFinalize<BlockNumberFor<Runtime>>,
{
	pub fn run_to_block(n: u32, author: AccountIdOf<Runtime>) -> HeaderFor<Runtime> {
		let mut last_header = None;
		loop {
			let block_number = frame_system::Pallet::<Runtime>::block_number();
			if block_number >= n.into() {
				break
			}
			// Set the new block number and author

			// Inherent is not created at every block, don't finalize parachain
			// system to avoid panicking.
			let header = frame_system::Pallet::<Runtime>::finalize();

			let pre_digest =
				Digest { logs: vec![DigestItem::PreRuntime(AURA_ENGINE_ID, author.encode())] };
			frame_system::Pallet::<Runtime>::reset_events();

			let next_block_number = block_number + 1u32.into();
			frame_system::Pallet::<Runtime>::initialize(
				&next_block_number,
				&header.hash(),
				&pre_digest,
			);
			AllPalletsWithoutSystem::on_initialize(next_block_number);
			last_header = Some(header);
		}
		last_header.expect("run_to_block empty block range")
	}

	pub fn run_to_block_with_finalize(n: u32) -> HeaderFor<Runtime> {
		let mut last_header = None;
		loop {
			let block_number = frame_system::Pallet::<Runtime>::block_number();
			if block_number >= n.into() {
				break
			}
			// Set the new block number and author
			let header = frame_system::Pallet::<Runtime>::finalize();

			let pre_digest = Digest {
				logs: vec![DigestItem::PreRuntime(AURA_ENGINE_ID, block_number.encode())],
			};
			frame_system::Pallet::<Runtime>::reset_events();

			let next_block_number = block_number + 1u32.into();
			frame_system::Pallet::<Runtime>::initialize(
				&next_block_number,
				&header.hash(),
				&pre_digest,
			);
			AllPalletsWithoutSystem::on_initialize(next_block_number);

			let parent_head = HeadData(header.encode());
			let sproof_builder = RelayStateSproofBuilder {
				para_id: <Runtime>::SelfParaId::get(),
				included_para_head: parent_head.clone().into(),
				..Default::default()
			};

			let (relay_parent_storage_root, relay_chain_state) =
				sproof_builder.into_state_root_and_proof();
			let inherent_data = ParachainInherentData {
				validation_data: PersistedValidationData {
					parent_head,
					relay_parent_number: (block_number.saturated_into::<u32>() * 2 + 1).into(),
					relay_parent_storage_root,
					max_pov_size: 100_000_000,
				},
				relay_chain_state,
				downward_messages: Default::default(),
				horizontal_messages: Default::default(),
			};

			let _ = cumulus_pallet_parachain_system::Pallet::<Runtime>::set_validation_data(
				Runtime::RuntimeOrigin::none(),
				inherent_data,
			);
			let _ = pallet_timestamp::Pallet::<Runtime>::set(
				Runtime::RuntimeOrigin::none(),
				300_u32.into(),
			);
			AllPalletsWithoutSystem::on_finalize(next_block_number);
			let header = frame_system::Pallet::<Runtime>::finalize();
			last_header = Some(header);
		}
		last_header.expect("run_to_block empty block range")
	}

	pub fn root_origin() -> <Runtime as frame_system::Config>::RuntimeOrigin {
		<Runtime as frame_system::Config>::RuntimeOrigin::root()
	}

	pub fn block_number() -> U256 {
		frame_system::Pallet::<Runtime>::block_number().into()
	}

	pub fn origin_of(
		account_id: AccountIdOf<Runtime>,
	) -> <Runtime as frame_system::Config>::RuntimeOrigin {
		<Runtime as frame_system::Config>::RuntimeOrigin::signed(account_id.into())
	}
}

impl<XcmConfig: xcm_executor::Config, AllPalletsWithoutSystem>
	RuntimeHelper<XcmConfig, AllPalletsWithoutSystem>
{
	pub fn do_transfer(
		from: Location,
		to: Location,
		(asset, amount): (Location, u128),
	) -> Result<AssetsInHolding, XcmError> {
		<XcmConfig::AssetTransactor as TransactAsset>::transfer_asset(
			&Asset { id: AssetId(asset), fun: Fungible(amount) },
			&from,
			&to,
			// We aren't able to track the XCM that initiated the fee deposit, so we create a
			// fake message hash here
			&XcmContext::with_message_id([0; 32]),
		)
	}
}

impl<
		Runtime: pallet_xcm::Config + cumulus_pallet_parachain_system::Config,
		AllPalletsWithoutSystem,
	> RuntimeHelper<Runtime, AllPalletsWithoutSystem>
{
	pub fn do_teleport_assets<HrmpChannelOpener>(
		origin: <Runtime as frame_system::Config>::RuntimeOrigin,
		dest: Location,
		beneficiary: Location,
		(asset, amount): (Location, u128),
		open_hrmp_channel: Option<(u32, u32)>,
		included_head: HeaderFor<Runtime>,
		slot_digest: &[u8],
		slot_durations: &SlotDurations,
	) -> DispatchResult
	where
		HrmpChannelOpener: frame_support::inherent::ProvideInherent<
			Call = cumulus_pallet_parachain_system::Call<Runtime>,
		>,
	{
		// open hrmp (if needed)
		if let Some((source_para_id, target_para_id)) = open_hrmp_channel {
			mock_open_hrmp_channel::<Runtime, HrmpChannelOpener>(
				source_para_id.into(),
				target_para_id.into(),
				included_head,
				slot_digest,
				slot_durations,
			);
		}

		// do teleport
		<pallet_xcm::Pallet<Runtime>>::limited_teleport_assets(
			origin,
			Box::new(dest.into()),
			Box::new(beneficiary.into()),
			Box::new((AssetId(asset), amount).into()),
			0,
			Unlimited,
		)
	}
}

impl<
		Runtime: cumulus_pallet_parachain_system::Config + pallet_xcm::Config,
		AllPalletsWithoutSystem,
	> RuntimeHelper<Runtime, AllPalletsWithoutSystem>
{
	#[deprecated(
		note = "Will be removed after Aug 2025; It uses hard-coded `Location::parent()`, \
		use `execute_as_governance_call` instead."
	)]
	pub fn execute_as_governance(call: Vec<u8>) -> Outcome {
		// prepare xcm as governance will do
		let xcm = Xcm(vec![
			UnpaidExecution { weight_limit: Unlimited, check_origin: None },
			Transact {
				origin_kind: OriginKind::Superuser,
				call: call.into(),
				fallback_max_weight: None,
			},
			ExpectTransactStatus(MaybeErrorCode::Success),
		]);

		// execute xcm as parent origin
		let mut hash = xcm.using_encoded(sp_io::hashing::blake2_256);
		<<Runtime as pallet_xcm::Config>::XcmExecutor>::prepare_and_execute(
			Location::parent(),
			xcm,
			&mut hash,
			Self::xcm_max_weight(XcmReceivedFrom::Parent),
			Weight::zero(),
		)
	}

	pub fn execute_as_governance_call<Call: Dispatchable + Encode>(
		call: Call,
		governance_origin: GovernanceOrigin<Call::RuntimeOrigin>,
	) -> Result<(), Either<DispatchError, XcmError>> {
		// execute xcm as governance would send
		let execute_xcm = |call: Call, governance_location, descend_origin| {
			// prepare xcm
			let xcm = if let Some(descend_origin) = descend_origin {
				Xcm::builder_unsafe().descend_origin(descend_origin)
			} else {
				Xcm::builder_unsafe()
			}
			.unpaid_execution(Unlimited, None)
			.transact(OriginKind::Superuser, None, call.encode())
			.expect_transact_status(MaybeErrorCode::Success)
			.build();

			let xcm_max_weight = Self::xcm_max_weight_for_location(&governance_location);
			let mut hash = xcm.using_encoded(sp_io::hashing::blake2_256);

			<<Runtime as pallet_xcm::Config>::XcmExecutor>::prepare_and_execute(
				governance_location,
				xcm,
				&mut hash,
				xcm_max_weight,
				Weight::zero(),
			)
		};

		match governance_origin {
			GovernanceOrigin::Location(location) =>
				execute_xcm(call, location, None).ensure_complete().map_err(Either::Right),
			GovernanceOrigin::LocationAndDescendOrigin(location, descend_origin) =>
				execute_xcm(call, location, Some(descend_origin))
					.ensure_complete()
					.map_err(Either::Right),
			GovernanceOrigin::Origin(origin) =>
				call.dispatch(origin).map(|_| ()).map_err(|e| Either::Left(e.error)),
		}
	}

	pub fn execute_as_origin<Call: GetDispatchInfo + Encode>(
		(origin, origin_kind): (Location, OriginKind),
		call: Call,
		maybe_buy_execution_fee: Option<Asset>,
	) -> Outcome {
		let mut instructions = if let Some(buy_execution_fee) = maybe_buy_execution_fee {
			vec![
				WithdrawAsset(buy_execution_fee.clone().into()),
				BuyExecution { fees: buy_execution_fee.clone(), weight_limit: Unlimited },
			]
		} else {
			vec![UnpaidExecution { check_origin: None, weight_limit: Unlimited }]
		};

		// prepare `Transact` xcm
		instructions.extend(vec![
			Transact { origin_kind, call: call.encode().into(), fallback_max_weight: None },
			ExpectTransactStatus(MaybeErrorCode::Success),
		]);
		let xcm = Xcm(instructions);
		let xcm_max_weight = Self::xcm_max_weight_for_location(&origin);

		// execute xcm as parent origin
		let mut hash = xcm.using_encoded(sp_io::hashing::blake2_256);
		<<Runtime as pallet_xcm::Config>::XcmExecutor>::prepare_and_execute(
			origin,
			xcm,
			&mut hash,
			xcm_max_weight,
			Weight::zero(),
		)
	}
}

/// Enum representing governance origin/location.
#[derive(Clone)]
pub enum GovernanceOrigin<RuntimeOrigin> {
	Location(Location),
	LocationAndDescendOrigin(Location, InteriorLocation),
	Origin(RuntimeOrigin),
}

pub enum XcmReceivedFrom {
	Parent,
	Sibling,
}

impl<ParachainSystem: cumulus_pallet_parachain_system::Config, AllPalletsWithoutSystem>
	RuntimeHelper<ParachainSystem, AllPalletsWithoutSystem>
{
	pub fn xcm_max_weight(from: XcmReceivedFrom) -> Weight {
		match from {
			XcmReceivedFrom::Parent => ParachainSystem::ReservedDmpWeight::get(),
			XcmReceivedFrom::Sibling => ParachainSystem::ReservedXcmpWeight::get(),
		}
	}

	pub fn xcm_max_weight_for_location(location: &Location) -> Weight {
		Self::xcm_max_weight(if location == &Location::parent() {
			XcmReceivedFrom::Parent
		} else {
			XcmReceivedFrom::Sibling
		})
	}
}

impl<Runtime: frame_system::Config + pallet_xcm::Config, AllPalletsWithoutSystem>
	RuntimeHelper<Runtime, AllPalletsWithoutSystem>
{
	pub fn assert_pallet_xcm_event_outcome(
		unwrap_pallet_xcm_event: &Box<dyn Fn(Vec<u8>) -> Option<pallet_xcm::Event<Runtime>>>,
		assert_outcome: fn(Outcome),
	) {
		assert_outcome(Self::get_pallet_xcm_event_outcome(unwrap_pallet_xcm_event));
	}

	pub fn get_pallet_xcm_event_outcome(
		unwrap_pallet_xcm_event: &Box<dyn Fn(Vec<u8>) -> Option<pallet_xcm::Event<Runtime>>>,
	) -> Outcome {
		<frame_system::Pallet<Runtime>>::events()
			.into_iter()
			.filter_map(|e| unwrap_pallet_xcm_event(e.event.encode()))
			.find_map(|e| match e {
				pallet_xcm::Event::Attempted { outcome } => Some(outcome),
				_ => None,
			})
			.expect("No `pallet_xcm::Event::Attempted(outcome)` event found!")
	}
}

impl<
		Runtime: frame_system::Config + cumulus_pallet_xcmp_queue::Config,
		AllPalletsWithoutSystem,
	> RuntimeHelper<Runtime, AllPalletsWithoutSystem>
{
	pub fn xcmp_queue_message_sent(
		unwrap_xcmp_queue_event: Box<
			dyn Fn(Vec<u8>) -> Option<cumulus_pallet_xcmp_queue::Event<Runtime>>,
		>,
	) -> Option<XcmHash> {
		<frame_system::Pallet<Runtime>>::events()
			.into_iter()
			.filter_map(|e| unwrap_xcmp_queue_event(e.event.encode()))
			.find_map(|e| match e {
				cumulus_pallet_xcmp_queue::Event::XcmpMessageSent { message_hash } =>
					Some(message_hash),
				_ => None,
			})
	}
}

pub fn assert_metadata<Fungibles, AccountId>(
	asset_id: impl Into<Fungibles::AssetId> + Clone,
	expected_name: &str,
	expected_symbol: &str,
	expected_decimals: u8,
) where
	Fungibles: frame_support::traits::fungibles::metadata::Inspect<AccountId>
		+ frame_support::traits::fungibles::Inspect<AccountId>,
{
	assert_eq!(Fungibles::name(asset_id.clone().into()), Vec::from(expected_name),);
	assert_eq!(Fungibles::symbol(asset_id.clone().into()), Vec::from(expected_symbol),);
	assert_eq!(Fungibles::decimals(asset_id.into()), expected_decimals);
}

pub fn assert_total<Fungibles, AccountId>(
	asset_id: impl Into<Fungibles::AssetId> + Clone,
	expected_total_issuance: impl Into<Fungibles::Balance>,
	expected_active_issuance: impl Into<Fungibles::Balance>,
) where
	Fungibles: frame_support::traits::fungibles::metadata::Inspect<AccountId>
		+ frame_support::traits::fungibles::Inspect<AccountId>,
{
	assert_eq!(Fungibles::total_issuance(asset_id.clone().into()), expected_total_issuance.into());
	assert_eq!(Fungibles::active_issuance(asset_id.into()), expected_active_issuance.into());
}

/// Helper function which emulates opening HRMP channel which is needed for `XcmpQueue` to pass.
///
/// Calls parachain-system's `create_inherent` in case the channel hasn't been opened before, and
/// thus requires additional parameters for validating it: latest included parachain head and
/// parachain AuRa-slot.
///
/// AuRa consensus hook expects pallets to be initialized, before calling this function make sure to
/// `run_to_block` at least once.
pub fn mock_open_hrmp_channel<
	C: cumulus_pallet_parachain_system::Config,
	T: ProvideInherent<Call = cumulus_pallet_parachain_system::Call<C>>,
>(
	sender: ParaId,
	recipient: ParaId,
	included_head: HeaderFor<C>,
	mut slot_digest: &[u8],
	slot_durations: &SlotDurations,
) {
	let slot = Slot::decode(&mut slot_digest).expect("failed to decode digest");
	// Convert para slot to relay chain.
	let timestamp = slot.saturating_mul(slot_durations.para.as_millis());
	let relay_slot = Slot::from_timestamp(timestamp.into(), slot_durations.relay);

	let n = 1_u32;
	let mut sproof_builder = RelayStateSproofBuilder {
		para_id: sender,
		included_para_head: Some(HeadData(included_head.encode())),
		hrmp_egress_channel_index: Some(vec![recipient]),
		current_slot: relay_slot,
		..Default::default()
	};
	sproof_builder.hrmp_channels.insert(
		HrmpChannelId { sender, recipient },
		AbridgedHrmpChannel {
			max_capacity: 10,
			max_total_size: 10_000_000_u32,
			max_message_size: 10_000_000_u32,
			msg_count: 0,
			total_size: 0_u32,
			mqc_head: None,
		},
	);

	let (relay_parent_storage_root, relay_chain_state) = sproof_builder.into_state_root_and_proof();
	let vfp = PersistedValidationData {
		relay_parent_number: n as RelayChainBlockNumber,
		relay_parent_storage_root,
		..Default::default()
	};
	// It is insufficient to push the validation function params
	// to storage; they must also be included in the inherent data.
	let inherent_data = {
		let mut inherent_data = InherentData::default();
		let system_inherent_data = ParachainInherentData {
			validation_data: vfp,
			relay_chain_state,
			downward_messages: Default::default(),
			horizontal_messages: Default::default(),
		};
		inherent_data
			.put_data(
				cumulus_primitives_parachain_inherent::INHERENT_IDENTIFIER,
				&system_inherent_data,
			)
			.expect("failed to put VFP inherent");
		inherent_data
	};

	// execute the block
	T::create_inherent(&inherent_data)
		.expect("got an inherent")
		.dispatch_bypass_filter(RawOrigin::None.into())
		.expect("dispatch succeeded");
}

impl<HrmpChannelSource: cumulus_primitives_core::XcmpMessageSource, AllPalletsWithoutSystem>
	RuntimeHelper<HrmpChannelSource, AllPalletsWithoutSystem>
{
	pub fn take_xcm(sent_to_para_id: ParaId) -> Option<VersionedXcm<()>> {
		match HrmpChannelSource::take_outbound_messages(10)[..] {
			[(para_id, ref mut xcm_message_data)] if para_id.eq(&sent_to_para_id.into()) => {
				let mut xcm_message_data = &xcm_message_data[..];
				// decode
				let _ = XcmpMessageFormat::decode(&mut xcm_message_data).expect("valid format");
				VersionedXcm::<()>::decode_with_depth_limit(
					MAX_XCM_DECODE_DEPTH,
					&mut xcm_message_data,
				)
				.map(|x| Some(x))
				.expect("result with xcm")
			},
			_ => return None,
		}
	}
}