Fix: linear accrual not overpassing maturity

pallets/loans/src/entities/loans.rs

@@ -14,7 +14,7 @@ use sp_runtime::{
 	},
 	DispatchError,
 };
-use sp_std::collections::btree_map::BTreeMap;
+use sp_std::{cmp::min, collections::btree_map::BTreeMap};
 
 use crate::{
 	entities::{
@@ -359,7 +359,8 @@ impl<T: Config> ActiveLoan<T> {
 				inner.adjust(Adjustment::Increase(amount.balance()?))?
 			}
 			ActivePricing::External(inner) => {
-				inner.adjust(Adjustment::Increase(amount.external()?), Zero::zero())?
+				let when = T::Time::now();
+				inner.adjust(Adjustment::Increase(amount.external()?), Zero::zero(), when)?
 			}
 		}
 
@@ -433,7 +434,8 @@ impl<T: Config> ActiveLoan<T> {
 			}
 			ActivePricing::External(inner) => {
 				let principal = amount.principal.external()?;
-				inner.adjust(Adjustment::Decrease(principal), amount.interest)?;
+				let when = min(T::Time::now(), self.schedule.maturity.date());
+				inner.adjust(Adjustment::Decrease(principal), amount.interest, when)?;
 			}
 		}
 

pallets/loans/src/entities/pricing/external.rs

@@ -143,6 +143,10 @@ impl<T: Config> ExternalActivePricing<T> {
 		self.info.price_id
 	}
 
+	pub fn settlement_price_updated(&self) -> Seconds {
+		self.settlement_price_updated
+	}
+
 	pub fn has_registered_price(&self, pool_id: T::PoolId) -> bool {
 		T::PriceRegistry::get(&self.info.price_id, &pool_id).is_ok()
 	}
@@ -298,6 +302,7 @@ impl<T: Config> ExternalActivePricing<T> {
 		&mut self,
 		amount_adj: Adjustment<ExternalAmount<T>>,
 		interest: T::Balance,
+		when: Seconds,
 	) -> DispatchResult {
 		self.outstanding_quantity = amount_adj
 			.clone()
@@ -313,7 +318,7 @@ impl<T: Config> ExternalActivePricing<T> {
 
 		self.interest.adjust_debt(interest_adj)?;
 		self.latest_settlement_price = amount_adj.abs().settlement_price;
-		self.settlement_price_updated = T::Time::now();
+		self.settlement_price_updated = when;
 
 		Ok(())
 	}

pallets/loans/src/tests/repay_loan.rs

@@ -812,3 +812,41 @@ fn with_unregister_price_id_and_oracle_not_required() {
 		);
 	});
 }
+
+#[test]
+fn with_external_pricing_and_overdue() {
+	new_test_ext().execute_with(|| {
+		let loan_id = util::create_loan(LoanInfo {
+			..util::base_external_loan()
+		});
+
+		let amount = ExternalAmount::new(QUANTITY, PRICE_VALUE);
+		util::borrow_loan(loan_id, PrincipalInput::External(amount));
+
+		// The loan is overdue
+		advance_time(YEAR * 2);
+
+		let amount = ExternalAmount::new(QUANTITY, PRICE_VALUE);
+		config_mocks(amount.balance().unwrap());
+		assert_ok!(Loans::repay(
+			RuntimeOrigin::signed(BORROWER),
+			POOL_A,
+			loan_id,
+			RepaidInput {
+				principal: PrincipalInput::External(amount),
+				interest: 0,
+				unscheduled: 0,
+			},
+		));
+
+		let active_loan = util::get_loan(loan_id);
+
+		let settlement_price_updated = match active_loan.pricing() {
+			ActivePricing::External(inner) => inner.settlement_price_updated(),
+			_ => unreachable!(),
+		};
+
+		// We must never overpass madurity date
+		assert_eq!(active_loan.maturity_date(), settlement_price_updated);
+	});
+}