Fix lm reward settlement

pallets/liquidity-mining/src/lib.rs

@@ -167,13 +167,19 @@ impl<T: Config> PoolInfo<T> {
 						v_new.saturating_sub(v_old).saturating_mul_int(user_deposit),
 					);
 
-					// Update the claimed of the reward
-					reward.claimed = reward.claimed.saturating_add(amount);
 					// Sync the gain_avg between `DepositData` and `RewardData`
 					deposit_data.gain_avgs.insert(*rtoken, v_new);
 					deposit_data.update_b = self.update_b;
 
-					to_rewards.push((*rtoken, amount));
+					let ed = T::MultiCurrency::minimum_balance(*rtoken);
+					let total =
+						T::MultiCurrency::total_balance(*rtoken, &user).saturating_add(amount);
+
+					if total >= ed {
+						// Update the claimed of the reward
+						reward.claimed = reward.claimed.saturating_add(amount);
+						to_rewards.push((*rtoken, amount));
+					}
 				}
 			}
 		}

pallets/liquidity-mining/src/mock.rs

@@ -93,7 +93,7 @@ impl frame_system::Config for Test {
 }
 
 parameter_types! {
-	pub const ExistentialDeposit: u128 = 0;
+	pub const ExistentialDeposit: u128 = 1_000_000;
 	pub const TransferFee: u128 = 0;
 	pub const CreationFee: u128 = 0;
 	pub const TransactionByteFee: u128 = 0;

pallets/liquidity-mining/src/tests.rs

@@ -2162,6 +2162,70 @@ fn claim_from_eb_farming_should_work() {
 	});
 }
 
+#[test]
+fn discard_reward_lower_than_ed_should_work() {
+	new_test_ext().execute_with(|| {
+		const PER_BLOCK: Balance = REWARD_AMOUNT / DAYS as Balance;
+		const HALF_ED_PER_BLOCK: Balance = ExistentialDeposit::get() / 2;
+
+		assert_ok!(LM::create_eb_farming_pool(
+			pallet_collective::RawOrigin::Member(TC_MEMBER_1).into(),
+			2001,
+			13,
+			20,
+			(REWARD_1, HALF_ED_PER_BLOCK * DAYS as Balance),
+			vec![(REWARD_2, REWARD_AMOUNT)].try_into().unwrap(),
+			DAYS,
+			1_000_000,
+			0
+		));
+
+		// It is unable to call Collective::execute(..) which is private;
+		assert_ok!(LM::charge(Some(INVESTOR).into(), 0));
+
+		assert_ok!(Tokens::reserve(FARMING_DEPOSIT_1, &USER_1, DEPOSIT_AMOUNT));
+		assert_ok!(Tokens::reserve(FARMING_DEPOSIT_2, &USER_1, DEPOSIT_AMOUNT));
+
+		assert_ok!(LM::deposit(Some(USER_1).into(), 0, DEPOSIT_AMOUNT));
+
+		let keeper = LM::pool(0).unwrap().keeper;
+
+		// The action will discard the reward of `reward_1`.
+		run_to_block(1);
+		assert_ok!(LM::claim(Some(USER_1).into(), 0));
+
+		assert_eq!(Tokens::accounts(USER_1, REWARD_1).free, 0);
+		assert_eq!(Tokens::accounts(USER_1, REWARD_2).free, PER_BLOCK);
+
+		run_to_block(3);
+		assert_ok!(LM::claim(Some(USER_1).into(), 0));
+
+		assert_eq!(Tokens::accounts(USER_1, REWARD_1).free, 2 * HALF_ED_PER_BLOCK);
+		assert_eq!(Tokens::accounts(USER_1, REWARD_2).free, 3 * PER_BLOCK);
+
+		run_to_block(4);
+		assert_ok!(LM::claim(Some(USER_1).into(), 0));
+
+		assert_eq!(Tokens::accounts(USER_1, REWARD_1).free, 3 * HALF_ED_PER_BLOCK);
+		assert_eq!(Tokens::accounts(USER_1, REWARD_2).free, 4 * PER_BLOCK);
+
+		run_to_block(DAYS);
+		assert_ok!(LM::redeem_all(Some(USER_1).into(), 0));
+
+		let reward_1 = (DAYS - 1) as Balance * HALF_ED_PER_BLOCK;
+		let reward_2 = DAYS as Balance * PER_BLOCK;
+
+		assert_eq!(Tokens::accounts(USER_1, REWARD_1).free, reward_1);
+		assert_eq!(Tokens::accounts(USER_1, REWARD_2).free, reward_2);
+
+		assert_eq!(Tokens::accounts(keeper.clone(), REWARD_1).free, 0);
+		assert_eq!(Tokens::accounts(keeper.clone(), REWARD_2).free, 0);
+
+		assert_eq!(Tokens::accounts(INVESTOR, REWARD_1).free, REWARD_AMOUNT - reward_1);
+		assert_eq!(Tokens::accounts(INVESTOR, REWARD_2).free, REWARD_AMOUNT - reward_2);
+	});
+}
+
 #[test]
 fn simple_integration_test() {
 	new_test_ext().execute_with(|| {