Add force_unstake to staking as root operation. (#3918)

* Add force_unstake to staking as root operation.

* Bump runtime

* Tests

* Update srml/staking/src/lib.rs

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

substrate/node/runtime/src/lib.rs

@@ -83,7 +83,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// and set impl_version to equal spec_version. If only runtime
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
-	spec_version: 184,
+	spec_version: 185,
 	impl_version: 185,
 	apis: RUNTIME_API_VERSIONS,
 };

substrate/srml/staking/src/lib.rs

@@ -993,6 +993,17 @@ decl_module! {
 			ensure_root(origin)?;
 			<Invulnerables<T>>::put(validators);
 		}
+
+		/// Force a current staker to become completely unstaked, immediately.
+		#[weight = sr_primitives::SimpleDispatchInfo::FreeOperational]
+		fn force_unstake(origin, stash: T::AccountId) {
+			ensure_root(origin)?;
+
+			// remove the lock.
+			T::Currency::remove_lock(STAKING_ID, &stash);
+			// remove all staking-related information.
+			Self::kill_stash(&stash);
+		}
 	}
 }
 

substrate/srml/staking/src/tests.rs

@@ -22,6 +22,28 @@ use sr_primitives::{assert_eq_error_rate, traits::OnInitialize};
 use sr_staking_primitives::offence::{OffenceDetails, OnOffenceHandler};
 use support::{assert_ok, assert_noop, assert_eq_uvec, traits::{Currency, ReservableCurrency}};
 
+#[test]
+fn force_unstake_works() {
+	// Verifies initial conditions of mock
+	ExtBuilder::default().build().execute_with(|| {
+		// Account 11 is stashed and locked, and account 10 is the controller
+		assert_eq!(Staking::bonded(&11), Some(10));
+		// Cant transfer
+		assert_noop!(
+			Balances::transfer(Origin::signed(11), 1, 10),
+			"account liquidity restrictions prevent withdrawal"
+		);
+		// Force unstake requires root.
+		assert_noop!(Staking::force_unstake(Origin::signed(11), 11), "RequireRootOrigin");
+		// We now force them to unstake
+		assert_ok!(Staking::force_unstake(Origin::ROOT, 11));
+		// No longer bonded.
+		assert_eq!(Staking::bonded(&11), None);
+		// Transfer works.
+		assert_ok!(Balances::transfer(Origin::signed(11), 1, 10));
+	});
+}
+
 #[test]
 fn basic_setup_works() {
 	// Verifies initial conditions of mock