add test for signer has not changed

pallets/staking/src/lib.rs

@@ -557,7 +557,7 @@ pub mod pallet {
             let signers_info = pallet_parameters::Pallet::<T>::signers_info();
 
             // removes first signer and pushes new signer to back if total signers not increased
-            if current_signers.len() < signers_info.total_signers as usize {
+            if current_signers.len() >= signers_info.total_signers as usize {
                 current_signers.remove(0);
             }
             current_signers.push(next_signer_up.clone());

pallets/staking/src/mock.rs

@@ -409,7 +409,7 @@ pub fn new_test_ext() -> sp_io::TestExternalities {
     pallet_parameters::GenesisConfig::<Test> {
         request_limit: 5u32,
         max_instructions_per_programs: 5u64,
-        total_signers: 5u8,
+        total_signers: 2u8,
         threshold: 2u8,
         _config: Default::default(),
     }

pallets/staking/src/tests.rs

@@ -20,6 +20,7 @@ use crate::{
 use codec::Encode;
 use frame_support::{assert_noop, assert_ok};
 use frame_system::{EventRecord, Phase};
+use pallet_parameters::SignersSize;
 use pallet_session::SessionManager;
 const NULL_ARR: [u8; 32] = [0; 32];
 
@@ -382,6 +383,15 @@ fn it_tests_new_session_handler() {
         assert_ok!(Staking::new_session_handler(&[1]));
         // does nothing as not enough validators
         assert_eq!(Staking::next_signers().unwrap().next_signers, vec![6, 3]);
+
+        pallet_parameters::SignersInfo::<Test>::put(SignersSize {
+            total_signers: 3,
+            threshold: 2,
+            last_session_change: 0,
+        });
+        assert_ok!(Staking::new_session_handler(&[6, 5, 3, 4]));
+        // Signer size increased is reflected as 5 is not removed from vec
+        assert_eq!(Staking::next_signers().unwrap().next_signers, vec![5, 6, 3]);
     });
 }