Fix a bug where if the user withdraws all debit and collateral, the s…

…ystem would not allow it. (#2109) Now minimum collateral amount is only maintained if user does not withdraw all of its collaterals Co-authored-by: Roy Yang <[email protected]>
AcalaNetwork · May 13, 2022 · ac5eb40 · ac5eb40
1 parent 45c4120
commit ac5eb40
Show file tree

Hide file tree

Showing 3 changed files with 24 additions and 3 deletions.
diff --git a/modules/cdp-engine/src/lib.rs b/modules/cdp-engine/src/lib.rs
@@ -214,7 +214,8 @@ pub mod module {
 		InvalidCollateralType,
 		/// Remain debit value in CDP below the dust amount
 		RemainDebitValueTooSmall,
-		/// Remain collateral value in CDP below the dust amount
+		/// Remain collateral value in CDP below the dust amount.
+		/// Withdraw all collateral or leave more than the minimum.
 		CollateralAmountBelowMinimum,
 		/// Feed price is invalid
 		InvalidFeedPrice,
@@ -1294,8 +1295,8 @@ impl<T: Config> RiskManager<T::AccountId, CurrencyId, Balance, Balance> for Pall
 				debit_value >= T::MinimumDebitValue::get(),
 				Error::<T>::RemainDebitValueTooSmall,
 			);
-		} else {
-			// check the collateral amount is above minimum when debit is 0
+		} else if !collateral_balance.is_zero() {
+			// If there are any collateral remaining, then it must be above the minimum
 			ensure!(
 				collateral_balance >= T::MinimumCollateralAmount::get(&currency_id),
 				Error::<T>::CollateralAmountBelowMinimum,

diff --git a/modules/cdp-engine/src/tests.rs b/modules/cdp-engine/src/tests.rs
@@ -1774,6 +1774,7 @@ fn minimal_collateral_works() {
 		);
 		assert_ok!(CDPEngineModule::check_position_valid(BTC, 9, 20, true));
 		assert_ok!(CDPEngineModule::check_position_valid(BTC, 10, 0, true));
+		assert_ok!(CDPEngineModule::check_position_valid(BTC, 0, 0, true));
 
 		// Adjust position fails if collateral is too small
 		assert_noop!(
@@ -1787,5 +1788,8 @@ fn minimal_collateral_works() {
 			CDPEngineModule::adjust_position(&ALICE, BTC, -1, 0),
 			Error::<Runtime>::CollateralAmountBelowMinimum,
 		);
+
+		// Allow the user to withdraw all assets
+		assert_ok!(CDPEngineModule::adjust_position(&ALICE, BTC, 0, 0));
 	});
 }
diff --git a/runtime/integration-tests/src/honzon.rs b/runtime/integration-tests/src/honzon.rs
@@ -662,5 +662,21 @@ fn cdp_engine_minimum_collateral_amount_works() {
 				(relaychain_minimum_collateral_amount - 1) as i128,
 				(MinimumDebitValue::get() * 10) as i128,
 			));
+
+			// Native collateral can be withdrawal in its entirety if debit is 0
+			assert_ok!(CdpEngine::adjust_position(
+				&AccountId::from(ALICE),
+				NATIVE_CURRENCY,
+				1i128 - (native_minimum_collateral_amount as i128),
+				-((MinimumDebitValue::get() * 10) as i128),
+			));
+
+			// Other tokens collateral can be withdrawal in its entirety if debit is 0
+			assert_ok!(CdpEngine::adjust_position(
+				&AccountId::from(ALICE),
+				RELAY_CHAIN_CURRENCY,
+				1i128 - (relaychain_minimum_collateral_amount as i128),
+				-((MinimumDebitValue::get() * 10) as i128),
+			));
 		});
 }