feat: validator reverts with message for user

Author: arnigudj

src/Validator.sol

@@ -2,6 +2,7 @@
 pragma solidity ^0.8.20;
 
 import {AccessControl} from "@openzeppelin/contracts/access/AccessControl.sol";
+import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
 import "./IValidator.sol";
 
 /**
@@ -53,13 +54,50 @@ contract Validator is AccessControl, IValidator {
         uint256 /* amount */
     ) external view override returns (bool valid) {
         if (isV1Frontend(msg.sender)) {
-            valid = !(isV1Blocked(from) || isV1Blocked(to));
-            if (!valid) {
-                return false;
+            if (isV1Blocked(from)) {
+                revert(
+                    string(
+                        abi.encodePacked(
+                            "Transfer not supported:",
+                            Strings.toHexString(from),
+                            " is blocked in V1. Please use V2 instead. See https://monerium.dev/docs/tokens"
+                        )
+                    )
+                );
             }
+            if (isV1Blocked(to)) {
+                revert(
+                    string(
+                        abi.encodePacked(
+                            "Transfer not supported:",
+                            Strings.toHexString(to),
+                            " is blocked in V1. Please use V2 instead. See https://monerium.dev/docs/tokens"
+                        )
+                    )
+                );
+            }
+        }
+        if (isBlacklisted(from)) {
+            revert(
+                string(
+                    abi.encodePacked(
+                        "Transfer not supported:",
+                        Strings.toHexString(from),
+                        " is blacklisted."
+                    )
+                )
+            );
         }
-        if (isBlacklisted(from) || isBlacklisted(to)) {
-            return false;
+        if (isBlacklisted(to)) {
+            revert(
+                string(
+                    abi.encodePacked(
+                        "Transfer not supported:",
+                        Strings.toHexString(to),
+                        " is blacklisted."
+                    )
+                )
+            );
         }
         return true;
     }

test/Validator.t.sol

@@ -66,15 +66,21 @@ contract ValidatorTest is Test {
 
         // Blocked by frontend
         vm.prank(frontend);
-        assertFalse(validator.validate(blocked, admin, 100));
+        vm.expectRevert("Transfer not supported:0x0000000000000000000000000000000000000004 is blocked in V1. Please use V2 instead. See https://monerium.dev/docs/tokens");
+        validator.validate(blocked, admin, 100);
+
         vm.prank(frontend);
-        assertFalse(validator.validate(admin, blocked, 100));
+        vm.expectRevert("Transfer not supported:0x0000000000000000000000000000000000000004 is blocked in V1. Please use V2 instead. See https://monerium.dev/docs/tokens");
+        validator.validate(admin, blocked, 100);
 
-        // Blacklisted always fails
+        // Blacklisted always reverts
         vm.prank(user);
-        assertFalse(validator.validate(blacklisted, admin, 100));
+        vm.expectRevert("Transfer not supported:0x0000000000000000000000000000000000000005 is blacklisted.");
+        validator.validate(blacklisted, admin, 100);
+
         vm.prank(user);
-        assertFalse(validator.validate(admin, blacklisted, 100));
+        vm.expectRevert("Transfer not supported:0x0000000000000000000000000000000000000005 is blacklisted.");
+        validator.validate(admin, blacklisted, 100);
     }
 
     function testContractId() public {