From 46a964e6032fbadf3769bec7992fc614adfb5065 Mon Sep 17 00:00:00 2001
From: vicnaum <vicnaum@gmail.com>
Date: Fri, 13 Oct 2023 19:00:09 +0200
Subject: [PATCH] misc: C4-168-N04 Allow to unfollow() for burnt target
 profiles T-16806

---
 contracts/libraries/FollowLib.sol |  3 ++-
 test/UnfollowTest.t.sol           | 25 +++++++++++++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/contracts/libraries/FollowLib.sol b/contracts/libraries/FollowLib.sol
index c3aedc4..f494370 100644
--- a/contracts/libraries/FollowLib.sol
+++ b/contracts/libraries/FollowLib.sol
@@ -63,10 +63,11 @@ library FollowLib {
         uint256 i;
         while (i < idsOfProfilesToUnfollow.length) {
             uint256 idOfProfileToUnfollow = idsOfProfilesToUnfollow[i];
-            ValidationLib.validateProfileExists(idOfProfileToUnfollow);
 
             address followNFT = StorageLib.getProfile(idOfProfileToUnfollow).followNFT;
 
+            // We don't validate the profile exists because we want to allow unfollowing a burnt profile.
+            // Because, if the profile never existed, followNFT will be address(0) and the call will revert.
             if (followNFT == address(0)) {
                 revert Errors.NotFollowing();
             }
diff --git a/test/UnfollowTest.t.sol b/test/UnfollowTest.t.sol
index f8b9bc7..90694fd 100644
--- a/test/UnfollowTest.t.sol
+++ b/test/UnfollowTest.t.sol
@@ -78,7 +78,7 @@ contract UnfollowTest is BaseTest {
 
         assertTrue(hub.isFollowing(testUnfollowerProfileId, targetProfileId));
 
-        vm.expectRevert(Errors.TokenDoesNotExist.selector);
+        vm.expectRevert(Errors.NotFollowing.selector);
 
         _unfollow({
             pk: testUnfollowerProfileOwnerPk,
@@ -190,6 +190,23 @@ contract UnfollowTest is BaseTest {
         assertFalse(hub.isFollowing(testUnfollowerProfileId, targetProfileId));
     }
 
+    function testUnfollowIfTargetProfileWasBurned() public {
+        assertTrue(hub.isFollowing(testUnfollowerProfileId, targetProfileId));
+
+        _effectivelyDisableProfileGuardian(targetProfileOwner);
+        vm.prank(targetProfileOwner);
+        hub.burn(targetProfileId);
+
+        _unfollow({
+            pk: testUnfollowerProfileOwnerPk,
+            unfollowerProfileId: testUnfollowerProfileId,
+            idsOfProfilesToUnfollow: _toUint256Array(targetProfileId)
+        });
+
+        // Asserts that the unfollow operation was still a success.
+        assertFalse(hub.isFollowing(testUnfollowerProfileId, targetProfileId));
+    }
+
     function _unfollow(
         uint256 pk,
         uint256 unfollowerProfileId,
@@ -238,11 +255,7 @@ contract UnfollowMetaTxTest is UnfollowTest, MetaTxNegatives {
         });
     }
 
-    function _executeMetaTx(
-        uint256 signerPk,
-        uint256 nonce,
-        uint256 deadline
-    ) internal virtual override {
+    function _executeMetaTx(uint256 signerPk, uint256 nonce, uint256 deadline) internal virtual override {
         hub.unfollowWithSig({
             unfollowerProfileId: testUnfollowerProfileId,
             idsOfProfilesToUnfollow: _toUint256Array(targetProfileId),