Fix admin of existing communities being replaced

pallets/communities/src/functions.rs

@@ -57,6 +57,7 @@ impl<T: Config> Pallet<T> {
 			!Self::community_exists(community_id),
 			Error::<T>::CommunityAlreadyExists
 		);
+		ensure!(!CommunityIdFor::<T>::contains_key(admin), Error::<T>::AlreadyAdmin);
 
 		if let Some((deposit, depositor, depositee)) = maybe_deposit {
 			T::Balances::transfer(

pallets/communities/src/lib.rs

@@ -349,6 +349,8 @@ pub mod pallet {
 		NoVoteCasted,
 		/// The poll
 		NoLocksInPlace,
+		/// The origin trying to register a community already controls another community
+		AlreadyAdmin,
 	}
 
 	// Dispatchable functions allows users to interact with the pallet and invoke

pallets/communities/src/tests/registry.rs

@@ -58,4 +58,19 @@ mod create {
 			assert_eq!(Balances::free_balance(ALICE), 5);
 		});
 	}
+
+	#[test]
+	fn fails_if_admin_already_controls_another_community() {
+		new_test_ext(&[], &[]).execute_with(|| {
+			const ANOTHER_COMMUNITY: CommunityId = 99;
+			// Simulate a pre-existing community
+			Info::<Test>::insert(COMMUNITY, CommunityInfo::default());
+
+			// Should fail adding another community with existing admin
+			assert_noop!(
+				Communities::create(Root.into(), COMMUNITY_ORIGIN, ANOTHER_COMMUNITY),
+				Error::AlreadyAdmin
+			);
+		});
+	}
 }