chore(staging-kusama-runtime): add tests for TreasuryBurnHandler.

relay/kusama/tests/treasury_burn_handler.rs

@@ -0,0 +1,166 @@
+// 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/>.
+
+//! TreasuryBurnHandler helper structure tests.
+//!
+//! Note: These tests emulate the effects of burning some amount on `pallet_treasury` via
+//! [`OnUnbalanced`], not the behaviour itself.
+
+use frame_support::{
+	parameter_types,
+	traits::{
+		tokens::fungible::{Inspect, Mutate},
+		Currency, ExistenceRequirement, Get, Imbalance, OnUnbalanced, WithdrawReasons,
+	},
+};
+use kusama_runtime_constants::currency::UNITS;
+use polkadot_primitives::{AccountId, Balance};
+use sp_arithmetic::Permill;
+use staging_kusama_runtime::{
+	dynamic_params::treasury::{self, BurnDestination, BurnPortion},
+	Balances, BurnDestinationAccount, Parameters, RuntimeOrigin, RuntimeParameters, Treasury,
+	TreasuryBurnHandler,
+};
+
+parameter_types! {
+	TreasuryAccount: AccountId = Treasury::account_id();
+}
+
+const BURN_DESTINATION_ACCOUNT: AccountId = AccountId::new([1u8; 32]);
+
+const TREASURY_AMOUNT: Balance = 10 * UNITS;
+const SURPLUS: Balance = UNITS;
+
+fn test(pre: impl FnOnce(), test: impl FnOnce(Balance)) {
+	sp_io::TestExternalities::default().execute_with(|| {
+		pre();
+
+		Balances::set_balance(&TreasuryAccount::get(), TREASURY_AMOUNT);
+
+		let amount_to_handle = TreasuryBurnHandler::get() * SURPLUS;
+		let burn = <Balances as Currency<_>>::withdraw(
+			&TreasuryAccount::get(),
+			SURPLUS,
+			WithdrawReasons::RESERVE,
+			ExistenceRequirement::KeepAlive,
+		)
+		.expect("withdrawing of `burn` is within balance limits; qed");
+
+		// Withdrawn surplus to burn it.
+		assert_eq!(Balances::balance(&TreasuryAccount::get()), TREASURY_AMOUNT - SURPLUS);
+
+		let (credit, burn) = burn.split(amount_to_handle);
+
+		// Burn amount that's not to handle.
+		<() as OnUnbalanced<_>>::on_unbalanced(burn);
+
+		assert_eq!(Balances::total_issuance(), TREASURY_AMOUNT - (SURPLUS - amount_to_handle));
+
+		// Let's handle the `credit`
+		TreasuryBurnHandler::on_unbalanced(credit);
+
+		test(amount_to_handle);
+
+		// Only the amount to handle was transferred to the burn destination account
+		// let burn_destination_account = BurnDestination::get();
+		let burn_destination_account = BURN_DESTINATION_ACCOUNT;
+		let burn_destination_account_balance =
+			<Balances as Inspect<_>>::total_balance(&burn_destination_account);
+
+		assert_eq!(burn_destination_account_balance, amount_to_handle);
+	})
+}
+
+#[test]
+fn on_burn_parameters_not_set_does_not_handle_burn() {
+	test(
+		|| {},
+		|amount_to_handle| {
+			// Amount to burn should be zero by default
+			assert_eq!(amount_to_handle, 0);
+		},
+	)
+}
+
+#[test]
+fn on_burn_portion_not_set_does_not_handle_burn() {
+	test(
+		|| {
+			Parameters::set_parameter(
+				RuntimeOrigin::root(),
+				RuntimeParameters::Treasury(treasury::Parameters::BurnDestination(
+					BurnDestination,
+					Some(BurnDestinationAccount(Some(BURN_DESTINATION_ACCOUNT))),
+				)),
+			)
+			.expect("parameters are set accordingly; qed");
+		},
+		|amount_to_handle| {
+			// Amount to burn should be zero by default
+			assert_eq!(amount_to_handle, 0);
+		},
+	)
+}
+
+#[test]
+fn on_burn_destination_not_set_does_not_handle_burn() {
+	let one_percent = Permill::from_percent(1);
+	test(
+		|| {
+			Parameters::set_parameter(
+				RuntimeOrigin::root(),
+				RuntimeParameters::Treasury(treasury::Parameters::BurnPortion(
+					BurnPortion,
+					Some(one_percent),
+				)),
+			)
+			.expect("parameters are set accordingly; qed");
+		},
+		|amount_to_handle| {
+			// Amount to burn should be zero by default
+			assert_eq!(amount_to_handle, 0);
+		},
+	)
+}
+
+#[test]
+fn on_burn_parameters_set_works() {
+	let one_percent = Permill::from_percent(1);
+	test(
+		|| {
+			Parameters::set_parameter(
+				RuntimeOrigin::root(),
+				RuntimeParameters::Treasury(treasury::Parameters::BurnDestination(
+					BurnDestination,
+					Some(BurnDestinationAccount(Some(BURN_DESTINATION_ACCOUNT))),
+				)),
+			)
+			.expect("parameters are set accordingly; qed");
+			Parameters::set_parameter(
+				RuntimeOrigin::root(),
+				RuntimeParameters::Treasury(treasury::Parameters::BurnPortion(
+					BurnPortion,
+					Some(one_percent),
+				)),
+			)
+			.expect("parameters are set accordingly; qed");
+		},
+		|amount_to_handle| {
+			// Amount to burn should be zero by default
+			assert_eq!(amount_to_handle, one_percent * SURPLUS);
+		},
+	)
+}