Revert move fee

Author: gztensor

pallets/subtensor/src/staking/stake_utils.rs

@@ -1075,13 +1075,21 @@ impl<T: Config> Pallet<T> {
     pub(crate) fn calculate_staking_fee(
         origin: Option<(&T::AccountId, u16)>,
         _origin_coldkey: &T::AccountId,
-        _destination: Option<(&T::AccountId, u16)>,
+        destination: Option<(&T::AccountId, u16)>,
         _destination_coldkey: &T::AccountId,
         alpha_estimate: I96F32,
     ) -> u64 {
         match origin {
             // If origin is defined, we are removing/moving stake
             Some((origin_hotkey, origin_netuid)) => {
+                if let Some((_destination_hotkey, destination_netuid)) = destination {
+                    // This is a stake move/swap/transfer
+                    if destination_netuid == origin_netuid {
+                        // If destination is on the same subnet, use the default fee
+                        return DefaultStakingFee::<T>::get();
+                    }
+                }
+
                 if origin_netuid == Self::get_root_netuid()
                     || SubnetMechanism::<T>::get(origin_netuid) == 0
                 {

pallets/subtensor/src/tests/staking2.rs

@@ -914,5 +914,35 @@ fn test_stake_fee_calculation() {
             I96F32::from_num(stake_amount),
         ); // Charged a dynamic fee
         assert_ne!(stake_fee_5, default_fee);
+
+        // Test stake fee for move between hotkeys on non-root
+        let stake_fee_6 = SubtensorModule::calculate_staking_fee(
+            Some((&hotkey1, netuid0)),
+            &coldkey1,
+            Some((&hotkey2, netuid0)),
+            &coldkey1,
+            I96F32::from_num(stake_amount),
+        ); // Charge the default fee
+        assert_eq!(stake_fee_6, default_fee);
+
+        // Test stake fee for move between coldkeys on non-root
+        let stake_fee_7 = SubtensorModule::calculate_staking_fee(
+            Some((&hotkey1, netuid0)),
+            &coldkey1,
+            Some((&hotkey1, netuid0)),
+            &coldkey2,
+            I96F32::from_num(stake_amount),
+        ); // Charge the default fee; stake did not leave the subnet.
+        assert_eq!(stake_fee_7, default_fee);
+
+        // Test stake fee for *swap* from non-root to non-root
+        let stake_fee_8 = SubtensorModule::calculate_staking_fee(
+            Some((&hotkey1, netuid0)),
+            &coldkey1,
+            Some((&hotkey1, netuid1)),
+            &coldkey1,
+            I96F32::from_num(stake_amount),
+        ); // Charged a dynamic fee
+        assert_ne!(stake_fee_8, default_fee);
     });
 }