Add new try-state check invariant for nomination-pools (points >= sta…

…ke) (#5465)

closes #5448

---------

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>
Co-authored-by: Ankan <10196091+Ank4n@users.noreply.github.com>

prdoc/pr_5465.prdoc

@@ -0,0 +1,10 @@
+title: try-state check invariant for nomination-pools (points >= stake)
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      Adds a new try-state invariant to the nomination pools that checks that for each bonded pool, the pool's points can never be lower than its staked balance.
+
+crates:
+  - name: pallet-nomination-pools
+    bump: minor

substrate/frame/nomination-pools/src/lib.rs

@@ -3658,6 +3658,7 @@ impl<T: Config> Pallet<T> {
 	/// * each `member.pool_id` must correspond to an existing `BondedPool.id` (which implies the
 	///   existence of the reward pool as well).
 	/// * count of all members must be less than `MaxPoolMembers`.
+	/// * each `BondedPool.points` must never be lower than the pool's balance.
 	///
 	/// Then, considering unbonding members:
 	///
@@ -3786,6 +3787,11 @@ impl<T: Config> Pallet<T> {
 				pool is being destroyed and the depositor is the last member",
 			);
 
+			ensure!(
+				bonded_pool.points >= bonded_pool.points_to_balance(bonded_pool.points),
+				"Each `BondedPool.points` must never be lower than the pool's balance"
+			);
+
 			expected_tvl += T::StakeAdapter::total_stake(Pool::from(bonded_pool.bonded_account()));
 
 			Ok(())