Add basic XCM emulator tests (#114)

This PR adds XCM emulator tests for Relay chains and Asset Hub System
parachains.

It adds them under new `integration-tests/emulated/` dir which lives at
the root of the repo and doesn't pollute the prod networks
code/crates/etc in any way. As you can see from the `diff`, no other
files outside `integration-tests` are touched by this PR (except
workspace `Cargo.toml` and `Cargo.lock`).

Tests added by this PR are rather old/limited, but I will update them
when we bump polkadot-sdk crates deps to `v1.4` or `v1.5` release. This
will bring in more refined tests for existing scenarios and many new
tests for new scenarios such as complex asset-transfers and bridging -
sending XCMs over bridge, and asset transfers between AHs on different
relays using bridge.

Also after bumping repo to sdk `v1.4` or `v1.5` release, we can also
drop 90% of `integration-tests/emulated/common` and get it from
`crates.io`.

Fixes #103

---------

Co-authored-by: Bastian Köcher <[email protected]>

.github/workflows/test.yml

@@ -55,7 +55,6 @@ jobs:
         run: cargo test --workspace --release --locked -q --features=runtime-metrics,try-runtime
         env:
           RUSTFLAGS: "-C debug-assertions -D warnings"
-          SKIP_WASM_BUILD: 1
 
       - name: Test all features
         run: cargo test --workspace --release --locked -q --features=runtime-benchmarks,runtime-metrics,try-runtime

Cargo.toml

@@ -19,6 +19,8 @@ members = [
 	"system-parachains/bridge-hubs/bridge-hub-polkadot",
 	"system-parachains/collectives/collectives-polkadot",
 	"system-parachains/gluttons/glutton-kusama",
+	"integration-tests/emulated/assets/asset-hub-kusama",
+	"integration-tests/emulated/assets/asset-hub-polkadot",
 ]
 
 [profile.release]

integration-tests/emulated/assets/asset-hub-kusama/Cargo.toml

@@ -0,0 +1,40 @@
+[package]
+name = "asset-hub-kusama-integration-tests"
+version = "1.0.0"
+authors.workspace = true
+edition.workspace = true
+license = "Apache-2.0"
+description = "Asset Hub Kusama runtime integration tests with xcm-emulator"
+publish = false
+
+[dependencies]
+codec = { package = "parity-scale-codec", version = "3.4.0" }
+assert_matches = "1.5.0"
+
+# Substrate
+sp-runtime = { version = "28.0.0" }
+frame-support = { version = "25.0.0" }
+frame-system = { version = "25.0.0" }
+pallet-assets = { version = "26.0.0" }
+pallet-balances = { version = "25.0.0" }
+pallet-asset-conversion = { version = "7.0.0" }
+
+# Polkadot
+polkadot-core-primitives = { version = "4.0.0" }
+polkadot-parachain-primitives = { version = "3.0.0" }
+polkadot-runtime-parachains = { version = "4.0.0" }
+xcm = { package = "staging-xcm", version = "4.0.0" }
+pallet-xcm = { version = "4.0.0" }
+
+# Cumulus
+parachains-common = { version = "4.0.0" }
+xcm-emulator = { version = "0.2.0" }
+asset-hub-kusama-runtime = { path = "../../../../system-parachains/asset-hubs/asset-hub-kusama" }
+
+# Local
+integration-tests-common = { path = "../../common" }
+
+[features]
+runtime-benchmarks = [
+    "integration-tests-common/runtime-benchmarks"
+]

integration-tests/emulated/assets/asset-hub-kusama/src/lib.rs

@@ -0,0 +1,92 @@
+// 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.
+
+#![cfg(not(feature = "runtime-benchmarks"))]
+
+pub use codec::Encode;
+pub use frame_support::{
+	assert_err, assert_ok,
+	pallet_prelude::Weight,
+	sp_runtime::{AccountId32, DispatchError, DispatchResult},
+	traits::fungibles::Inspect,
+};
+pub use integration_tests_common::{
+	constants::{
+		asset_hub_kusama::ED as ASSET_HUB_KUSAMA_ED, kusama::ED as KUSAMA_ED, PROOF_SIZE_THRESHOLD,
+		REF_TIME_THRESHOLD, XCM_V3,
+	},
+	xcm_helpers::{xcm_transact_paid_execution, xcm_transact_unpaid_execution},
+	AssetHubKusama, AssetHubKusamaPallet, AssetHubKusamaReceiver, AssetHubKusamaSender, Kusama,
+	KusamaPallet, KusamaReceiver, KusamaSender, PenpalKusamaA, PenpalKusamaAPallet,
+	PenpalKusamaAReceiver, PenpalKusamaASender, PenpalKusamaB, PenpalKusamaBPallet,
+};
+pub use parachains_common::{AccountId, Balance};
+pub use xcm::{
+	prelude::{AccountId32 as AccountId32Junction, *},
+	v3::{Error, NetworkId::Kusama as KusamaId},
+};
+pub use xcm_emulator::{
+	assert_expected_events, bx, helpers::weight_within_threshold, Chain, Parachain as Para,
+	RelayChain as Relay, Test, TestArgs, TestContext, TestExt,
+};
+
+pub const ASSET_ID: u32 = 1;
+pub const ASSET_MIN_BALANCE: u128 = 1000;
+// `Assets` pallet index
+pub const ASSETS_PALLET_ID: u8 = 50;
+
+pub type RelayToSystemParaTest = Test<Kusama, AssetHubKusama>;
+pub type SystemParaToRelayTest = Test<AssetHubKusama, Kusama>;
+pub type SystemParaToParaTest = Test<AssetHubKusama, PenpalKusamaA>;
+
+/// Returns a `TestArgs` instance to be used for the Relay Chain across integration tests
+pub fn relay_test_args(amount: Balance) -> TestArgs {
+	TestArgs {
+		dest: Kusama::child_location_of(AssetHubKusama::para_id()),
+		beneficiary: AccountId32Junction {
+			network: None,
+			id: AssetHubKusamaReceiver::get().into(),
+		}
+		.into(),
+		amount,
+		assets: (Here, amount).into(),
+		asset_id: None,
+		fee_asset_item: 0,
+		weight_limit: WeightLimit::Unlimited,
+	}
+}
+
+/// Returns a `TestArgs` instance to be used for the System Parachain across integration tests
+pub fn system_para_test_args(
+	dest: MultiLocation,
+	beneficiary_id: AccountId32,
+	amount: Balance,
+	assets: MultiAssets,
+	asset_id: Option<u32>,
+) -> TestArgs {
+	TestArgs {
+		dest,
+		beneficiary: AccountId32Junction { network: None, id: beneficiary_id.into() }.into(),
+		amount,
+		assets,
+		asset_id,
+		fee_asset_item: 0,
+		weight_limit: WeightLimit::Unlimited,
+	}
+}
+
+#[cfg(test)]
+#[cfg(not(feature = "runtime-benchmarks"))]
+mod tests;