make distribute_rewards transactional

pallets/pooled-staking/src/mock.rs

@@ -110,8 +110,20 @@ impl frame_system::Config for Runtime {
     type MaxConsumers = ConstU32<16>;
 }
 
+/// Allows to change ED mid-test.
+pub struct MockExistentialDeposit;
+impl MockExistentialDeposit {
+    pub fn get() -> Balance {
+        frame_support::storage::unhashed::get(b":mock_ed").unwrap_or(1)
+    }
+
+    pub fn set(amount: Balance) {
+        frame_support::storage::unhashed::put(b":mock_ed", &amount);
+    } 
+}
+
 parameter_types! {
-    pub const ExistentialDeposit: u128 = 1;
+    pub ExistentialDeposit: u128 = MockExistentialDeposit::get();
 }
 
 impl pallet_balances::Config for Runtime {

pallets/pooled-staking/src/pools.rs

@@ -456,6 +456,7 @@ impl<T: Config> ManualRewards<T> {
 /// absorbed in the ManualRewards distribution, which simply consist of
 /// transfering the funds to the candidate account.
 #[allow(dead_code)]
+#[frame_support::transactional]
 pub fn distribute_rewards<T: Config>(
     candidate: &Candidate<T>,
     rewards: CreditOf<T>,

pallets/pooled-staking/src/tests/rewards.rs

@@ -22,6 +22,8 @@ use {
         Pallet, TargetPool,
     },
     tp_traits::DistributeRewards,
+    frame_support::assert_err,
+    sp_runtime::DispatchError,
 };
 
 struct Delegation {
@@ -582,3 +584,48 @@ fn delegator_only_candidate_no_stake_auto_compounding() {
         )
     });
 }
+
+#[test]
+fn reward_distribution_is_transactional() {
+    ExtBuilder::default().build().execute_with(|| {
+        use crate::traits::Timer;
+        let request_time = <Runtime as crate::Config>::JoiningRequestTimer::now();
+
+        assert_ok!(Staking::request_delegate(
+            RuntimeOrigin::signed(ACCOUNT_CANDIDATE_1.into()),
+            ACCOUNT_CANDIDATE_1.into(),
+            TargetPool::AutoCompounding,
+            1_000_000_000,
+        ));
+
+        // Wait for delegation to be executable
+        for _ in 0..BLOCKS_TO_WAIT {
+            roll_one_block();
+        }
+
+        assert_ok!(Staking::execute_pending_operations(
+            RuntimeOrigin::signed(ACCOUNT_CANDIDATE_1.into()),
+            vec![PendingOperationQuery {
+                delegator: ACCOUNT_CANDIDATE_1.into(),
+                operation: PendingOperationKey::JoiningAutoCompounding {
+                    candidate: ACCOUNT_CANDIDATE_1.into(),
+                    at: request_time
+                },
+            }]
+        ));
+
+        let total_staked_before = pools::AutoCompounding::<Runtime>::total_staked(&ACCOUNT_CANDIDATE_1.into());
+
+        // Increase ED to make reward destribution fail when resolving
+        // credit to Staking account.
+        MockExistentialDeposit::set(u128::MAX);
+
+        let rewards = Balances::issue(1_000_000_000);
+        assert_err!(Staking::distribute_rewards(ACCOUNT_CANDIDATE_1.into(), rewards), DispatchError::NoProviders);
+
+        let total_staked_after = pools::AutoCompounding::<Runtime>::total_staked(&ACCOUNT_CANDIDATE_1.into());
+        assert_eq!(total_staked_before, total_staked_after, "distribution should be reverted");
+
+
+    })
+}