Store (de)registration messages in contract storage

src/IValidatorRegistry.sol

@@ -2,19 +2,16 @@
 pragma solidity ^0.8.20;
 
 interface IValidatorRegistry {
-    function register(
-        bytes memory registrationMessage,
-        bytes memory registrationSignature
-    ) external;
+    struct Update {
+        bytes message;
+        bytes signature;
+    }
 
-    function deregister(
-        bytes memory deregistrationMessage,
-        bytes memory deregistrationSignature
-    ) external;
+    function getNumUpdates() external view returns (uint256);
 
-    event Registration(bytes registrationMessage, bytes registrationSignature);
-    event Deregistration(
-        bytes deregistrationMessage,
-        bytes deregistrationSignature
-    );
+    function getUpdate(uint256 i) external view returns (Update memory);
+
+    function update(bytes memory message, bytes memory signature) external;
+
+    event Updated(bytes message, bytes signature);
 }

src/ValidatorRegistry.sol

@@ -4,17 +4,18 @@ pragma solidity ^0.8.20;
 import "src/IValidatorRegistry.sol";
 
 contract ValidatorRegistry is IValidatorRegistry {
-    function register(
-        bytes memory registrationMessage,
-        bytes memory registrationSignature
-    ) external {
-        emit Registration(registrationMessage, registrationSignature);
+    Update[] updates;
+
+    function update(bytes memory message, bytes memory signature) external {
+        updates.push(Update({message: message, signature: signature}));
+        emit Updated(message, signature);
+    }
+
+    function getNumUpdates() external view returns (uint256) {
+        return updates.length;
     }
 
-    function deregister(
-        bytes memory deregistrationMessage,
-        bytes memory deregistrationSignature
-    ) external {
-        emit Deregistration(deregistrationMessage, deregistrationSignature);
+    function getUpdate(uint256 i) external view returns (Update memory) {
+        return updates[i];
     }
 }

test/ValidatorRegistry.t.sol

@@ -6,35 +6,58 @@ import "../src/IValidatorRegistry.sol";
 import "../src/ValidatorRegistry.sol";
 
 contract ValidatorRegistryTest is Test {
-    event Registration(bytes registrationMessage, bytes registrationSignature);
-    event Deregistration(
-        bytes deregistrationMessage,
-        bytes deregistrationSignature
-    );
+    event Updated(bytes message, bytes signature);
 
     IValidatorRegistry registry;
 
     function setUp() public {
         registry = new ValidatorRegistry();
     }
 
-    function testRegistration() public {
+    function testUpdate() public {
         bytes memory message = bytes("msg");
         bytes memory signature = bytes("sig");
 
         vm.expectEmit(address(registry));
-        emit Registration(message, signature);
+        emit Updated(message, signature);
 
-        registry.register(message, signature);
+        registry.update(message, signature);
     }
 
-    function testDeregistration() public {
-        bytes memory message = bytes("msg");
-        bytes memory signature = bytes("sig");
-
-        vm.expectEmit(address(registry));
-        emit Deregistration(message, signature);
+    function testGetters() public {
+        assertEq(registry.getNumUpdates(), 0);
+        vm.expectRevert();
+        registry.getUpdate(0);
+
+        IValidatorRegistry.Update memory up1 = IValidatorRegistry.Update({
+            message: bytes("msg1"),
+            signature: bytes("sig1")
+        });
+        IValidatorRegistry.Update memory up2 = IValidatorRegistry.Update({
+            message: bytes("msg2"),
+            signature: bytes("sig1")
+        });
+        IValidatorRegistry.Update memory up3 = IValidatorRegistry.Update({
+            message: bytes("msg3"),
+            signature: bytes("sig3")
+        });
+
+        registry.update(up1.message, up1.signature);
+        registry.update(up2.message, up2.signature);
+        registry.update(up3.message, up3.signature);
+
+        assertEq(registry.getNumUpdates(), 3);
+        assertTrue(cmpUpdates(registry.getUpdate(0), up1));
+        assertTrue(cmpUpdates(registry.getUpdate(1), up2));
+        assertTrue(cmpUpdates(registry.getUpdate(2), up3));
+        vm.expectRevert();
+        registry.getUpdate(3);
+    }
 
-        registry.deregister(message, signature);
+    function cmpUpdates(
+        IValidatorRegistry.Update memory up1,
+        IValidatorRegistry.Update memory up2
+    ) internal pure returns (bool) {
+        return keccak256(abi.encode(up1)) == keccak256(abi.encode(up2));
     }
 }