issue ERC20 staking rewards (native rewards TBD)

contracts/staking/ERC20TokenStakingManager.sol

@@ -123,4 +123,9 @@ contract ERC20TokenStakingManager is
     function _unlock(uint256 value, address to) internal virtual override {
         _getERC20StakingManagerStorage()._token.safeTransfer(to, value);
     }
+
+    function _reward(address account, uint256 amount) internal virtual override {
+        ERC20TokenStakingManagerStorage storage $ = _getERC20StakingManagerStorage();
+        $._token.mint(account, amount);
+    }
 }

contracts/staking/NativeTokenStakingManager.sol

@@ -82,4 +82,9 @@ contract NativeTokenStakingManager is
     function _unlock(uint256 value, address to) internal virtual override {
         payable(to).sendValue(value);
     }
+
+    // solhint-disable-next-line no-empty-blocks
+    function _reward(address account, uint256 amount) internal virtual override {
+        // TODO: call the native minter precompile to mint `amount` for `account`
+    }
 }

contracts/staking/PoSValidatorManager.sol

@@ -98,6 +98,14 @@ abstract contract PoSValidatorManager is IPoSValidatorManager, ValidatorManager
 
     function completeEndValidation(uint32 messageIndex) external {
         Validator memory validator = _completeEndValidation(messageIndex);
+
+        PoSValidatorManagerStorage storage $ = _getPoSValidatorManagerStorage();
+        uint256 rewardAmount = $._rewardCalculator.calculateReward(
+            validator.weight, validator.startedAt, validator.endedAt, 0, 0
+        );
+
+        _reward(validator.owner, rewardAmount);
+
         _unlock(validator.weight, validator.owner);
     }
 
@@ -376,4 +384,6 @@ abstract contract PoSValidatorManager is IPoSValidatorManager, ValidatorManager
             "PoSValidatorManager: delegation registration not pending"
         );
     }
+
+    function _reward(address account, uint256 amount) internal virtual;
 }

contracts/staking/tests/ERC20TokenStakingManagerTests.t.sol

@@ -10,6 +10,7 @@ import {ERC20TokenStakingManager} from "../ERC20TokenStakingManager.sol";
 import {ValidatorManagerSettings} from "../interfaces/IValidatorManager.sol";
 import {PoSValidatorManagerSettings} from "../interfaces/IPoSValidatorManager.sol";
 import {IRewardCalculator} from "../interfaces/IRewardCalculator.sol";
+import {ExampleRewardCalculator} from "../ExampleRewardCalculator.sol";
 import {ICMInitializable} from "../../utilities/ICMInitializable.sol";
 import {ExampleERC20} from "@mocks/ExampleERC20.sol";
 import {IERC20Mintable} from "../interfaces/IERC20Mintable.sol";
@@ -37,7 +38,7 @@ contract ERC20TokenStakingManagerTest is PoSValidatorManagerTest {
                 minimumStakeAmount: DEFAULT_MINIMUM_STAKE,
                 maximumStakeAmount: DEFAULT_MAXIMUM_STAKE,
                 minimumStakeDuration: DEFAULT_MINIMUM_STAKE_DURATION,
-                rewardCalculator: IRewardCalculator(address(0))
+                rewardCalculator: IRewardCalculator(new ExampleRewardCalculator(DEFAULT_REWARD_RATE))
             }),
             token
         );

contracts/staking/tests/NativeTokenStakingManagerTests.t.sol

@@ -10,6 +10,7 @@ import {NativeTokenStakingManager} from "../NativeTokenStakingManager.sol";
 import {ValidatorManagerSettings} from "../interfaces/IValidatorManager.sol";
 import {PoSValidatorManagerSettings} from "../interfaces/IPoSValidatorManager.sol";
 import {IRewardCalculator} from "../interfaces/IRewardCalculator.sol";
+import {ExampleRewardCalculator} from "../ExampleRewardCalculator.sol";
 import {ICMInitializable} from "../../utilities/ICMInitializable.sol";
 
 // TODO: Remove this once all unit tests implemented
@@ -30,7 +31,7 @@ contract NativeTokenStakingManagerTest is PoSValidatorManagerTest {
                 minimumStakeAmount: DEFAULT_MINIMUM_STAKE,
                 maximumStakeAmount: DEFAULT_MAXIMUM_STAKE,
                 minimumStakeDuration: DEFAULT_MINIMUM_STAKE_DURATION,
-                rewardCalculator: IRewardCalculator(address(0))
+                rewardCalculator: IRewardCalculator(new ExampleRewardCalculator(DEFAULT_REWARD_RATE))
             })
         );
         validatorManager = app;

contracts/staking/tests/PoSValidatorManagerTests.t.sol

@@ -21,6 +21,7 @@ abstract contract PoSValidatorManagerTest is ValidatorManagerTest {
     uint64 public constant DEFAULT_DELEGATOR_END_DELEGATION_TIMESTAMP = uint64(4000);
     address public constant DEFAULT_DELEGATOR_ADDRESS =
         address(0x1234123412341234123412341234123412341234);
+    uint64 public constant DEFAULT_REWARD_RATE = uint64(10);
 
     PoSValidatorManager public posValidatorManager;