feat: fix trusted attester linked list clearing

src/core/TrustManager.sol

@@ -27,6 +27,20 @@ abstract contract TrustManager is IRegistry {
 
     mapping(address account => TrustedAttesterRecord attesters) internal $accountToAttester;
 
+    function _requireEmptyList(TrustedAttesterRecord storage $trustedAttester) internal view {
+        address _tmp = $trustedAttester.attester;
+
+        // if the first entry is zero, the trusted list was not previously initialized, and can thus be safely set.
+        if (_tmp == ZERO_ADDRESS) return;
+
+        // otherwise, loop over the linked list to check if it is empty
+        // find the last entry in the linked list.
+        for (uint256 i; i <= type(uint8).max; i++) {
+            _tmp = $trustedAttester.linkedAttesters[_tmp][msg.sender];
+            if (_tmp == ZERO_ADDRESS) return;
+        }
+    }
+
     /**
      * @inheritdoc IERC7484
      */
@@ -49,6 +63,9 @@ abstract contract TrustManager is IRegistry {
             revert InvalidThreshold();
         }
 
+        // ensure that the trusted attester list is cleared before re-initializing it.
+        _requireEmptyList($trustedAttester);
+
         $trustedAttester.attesterCount = uint8(attestersLength);
         $trustedAttester.threshold = threshold;
         $trustedAttester.attester = attesters[0];

test/TrustedAttesterList.t.sol

@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+import "./Attestation.t.sol";
+import "src/DataTypes.sol";
+import { LibSort } from "solady/utils/LibSort.sol";
+
+contract POCTest is AttestationTest {
+    using LibSort for address[];
+
+    function setUp() public override {
+        super.setUp();
+    }
+
+    function testPOC() external prankWithAccount(smartAccount1) {
+        uint8 threshold = 1;
+        address[] memory trustedAttesters = new address[](3);
+        trustedAttesters[0] = address(attester1.addr);
+        trustedAttesters[1] = address(attester2.addr);
+        trustedAttesters[2] = makeAddr("attester3");
+
+        trustedAttesters.sort();
+        trustedAttesters.uniquifySorted();
+
+        registry.trustAttesters(threshold, trustedAttesters);
+
+        address[] memory result = registry.findTrustedAttesters(smartAccount1.addr);
+
+        assertEq(result.length, trustedAttesters.length);
+        for (uint256 i; i < trustedAttesters.length; i++) {
+            assertEq(result[i], trustedAttesters[i]);
+        }
+
+        _make_WhenUsingValidECDSA(attester2);
+        registry.check(address(module1), ModuleType.wrap(1));
+
+        address[] memory newTrustedAttesters = new address[](1);
+        newTrustedAttesters[0] = address(attester1.addr);
+        registry.trustAttesters(1, newTrustedAttesters);
+        address[] memory newResult = registry.findTrustedAttesters(smartAccount1.addr);
+        assertEq(newResult.length, 1);
+        assertEq(newResult[0], address(attester1.addr));
+
+        registry.check(address(module1), ModuleType.wrap(1));
+    }
+}