Merge pull request #1383 from galacticcouncil/fix/dca-atoken-rounding

fix: DCA slippage limit calculation

Author: dmoka

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "runtime-integration-tests"
-version = "1.74.1"
+version = "1.75.0"
 description = "Integration tests"
 authors = ["GalacticCouncil"]
 edition = "2021"

integration-tests/Cargo.toml

@@ -2119,6 +2119,62 @@ mod omnipool {
 			assert_balance!(ALICE.into(), HDX, 0);
 		});
 	}
+
+	#[test]
+	fn sell_schedule_should_use_slippage_limit_when_min_amount_out_is_zero() {
+		TestNet::reset();
+		Hydra::execute_with(|| {
+			//Arrange
+			init_omnipool_with_oracle_for_block_10();
+			let alice_init_hdx_balance = 5000 * UNITS;
+			assert_ok!(Balances::force_set_balance(
+				RuntimeOrigin::root(),
+				ALICE.into(),
+				alice_init_hdx_balance,
+			));
+
+			let dca_budget = 1100 * UNITS;
+			let amount_to_sell = 100 * UNITS;
+
+			// Create sell schedule with min_amount_out = 0
+			// This means last_block_slippage_min_limit will be used as the effective limit
+			let schedule = Schedule {
+				owner: AccountId::from(ALICE),
+				period: 5u32,
+				total_amount: dca_budget,
+				max_retries: None,
+				stability_threshold: None,
+				slippage: Some(Permill::from_percent(5)),
+				order: Order::Sell {
+					asset_in: HDX,
+					asset_out: DAI,
+					amount_in: amount_to_sell,
+					min_amount_out: 0,
+					route: create_bounded_vec(vec![Trade {
+						pool: PoolType::Omnipool,
+						asset_in: HDX,
+						asset_out: DAI,
+					}]),
+				},
+			};
+			create_schedule(ALICE, schedule);
+
+			let alice_dai_before = Currencies::free_balance(DAI, &ALICE.into());
+
+			//Act
+			go_to_block(12);
+
+			//Assert - DCA executed successfully and schedule is still alive
+			let alice_dai_after = Currencies::free_balance(DAI, &ALICE.into());
+			assert!(
+				alice_dai_after > alice_dai_before,
+				"ALICE should have received DAI from the trade"
+			);
+
+			let schedule = DCA::schedules(0);
+			assert!(schedule.is_some(), "DCA schedule should still be alive after execution");
+		});
+	}
 }
 
 mod fee {

integration-tests/src/dca.rs

@@ -1,6 +1,6 @@
 [package]
 name = 'pallet-dca'
-version = "1.16.1"
+version = "1.17.0"
 description = 'A pallet to manage DCA scheduling'
 authors = ['GalacticCouncil']
 edition = '2021'

pallets/dca/Cargo.toml

@@ -830,16 +830,26 @@ impl<T: Config> Pallet<T> {
 				let last_trade = trade_amounts.last().defensive_ok_or(Error::<T>::InvalidState)?;
 				let amount_out = last_trade.amount_out;
 
-				if *min_amount_out > last_block_slippage_min_limit {
+				let effective_min_limit = if *min_amount_out > last_block_slippage_min_limit {
 					ensure!(amount_out >= *min_amount_out, Error::<T>::TradeLimitReached);
+					amount_out
 				} else {
 					ensure!(
 						amount_out >= last_block_slippage_min_limit,
 						Error::<T>::SlippageLimitReached
 					);
+					// Use slippage limit to mainly absorb aToken rounding errors
+					last_block_slippage_min_limit
 				};
 
-				T::RouteExecutor::sell(origin, *asset_in, *asset_out, amount_to_sell, amount_out, route.clone())?;
+				T::RouteExecutor::sell(
+					origin,
+					*asset_in,
+					*asset_out,
+					amount_to_sell,
+					effective_min_limit,
+					route.clone(),
+				)?;
 
 				Ok(AmountInAndOut {
 					amount_in: amount_to_sell,

pallets/dca/src/lib.rs

@@ -1,6 +1,6 @@
 [package]
 name = "hydradx-runtime"
-version = "403.0.0"
+version = "404.0.0"
 authors = ["GalacticCouncil"]
 edition = "2021"
 license = "Apache 2.0"

runtime/hydradx/Cargo.toml

@@ -129,7 +129,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: Cow::Borrowed("hydradx"),
 	impl_name: Cow::Borrowed("hydradx"),
 	authoring_version: 1,
-	spec_version: 403,
+	spec_version: 404,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 1,