Contract and tests cleanups

backend/contracts/NftMarketplaceV2.sol

@@ -42,12 +42,6 @@ contract NftMarketplaceV2 is ReentrancyGuard, Ownable {
   /// @notice NftAddress -> Token ID -> Price
   mapping(address => mapping(uint256 => uint256)) public listings;
 
-  /// @notice UserAddress -> Funds
-  // For increased security: https://fravoll.github.io/solidity-patterns/pull_over_push.html
-  // Why using call: https://consensys.github.io/smart-contract-best-practices/development-recommendations/general/external-calls/#dont-use-transfer-or-send
-  // Good practice: https://docs.soliditylang.org/en/develop/security-considerations.html?highlight=check%20effects#use-the-checks-effects-interactions-pattern
-  // mapping(address => uint256) private funds;
-
   /// @notice UserAddress -> Deployed NFT contract addresses
   mapping(address => address[]) public nfts;
 
@@ -113,11 +107,10 @@ contract NftMarketplaceV2 is ReentrancyGuard, Ownable {
     // Set the price of the token (which lists it in the marketplace)
     listings[_nftAddress][_tokenId] = _price;
 
-    // Add the listing fee to the funds for the contract owner
+    // Send the listing fee to the marketplace owner
     address owner = owner();
-    // funds[owner] += msg.value;
-    (bool success, ) = payable(owner).call{value: msg.value}(""); // when funds aren't used
-    require(success, "Transfer failed"); // when funds aren't used
+    (bool success, ) = payable(owner).call{value: msg.value}("");
+    require(success, "Transfer failed");
 
     // Emit event
     emit ItemListed(msg.sender, _nftAddress, _tokenId, _price);
@@ -131,9 +124,9 @@ contract NftMarketplaceV2 is ReentrancyGuard, Ownable {
     alreadyListed(_nftAddress, _tokenId)
   {
     IERC721 nft = IERC721(_nftAddress);
-    address owner = nft.ownerOf(_tokenId);
+    address listingOwner = nft.ownerOf(_tokenId);
     require(
-      msg.sender == owner || msg.sender == _nftAddress,
+      msg.sender == listingOwner || msg.sender == owner() || msg.sender == _nftAddress,
       "Caller isn't owner or nft contract."
     );
     delete (listings[_nftAddress][_tokenId]);
@@ -153,11 +146,10 @@ contract NftMarketplaceV2 is ReentrancyGuard, Ownable {
     require(msg.value == listings[_nftAddress][_tokenId], "Price mismatch.");
     IERC721 nft = IERC721(_nftAddress);
     address owner = nft.ownerOf(_tokenId);
-    // funds[owner] += msg.value;
     delete (listings[_nftAddress][_tokenId]);
     IERC721(_nftAddress).safeTransferFrom(owner, msg.sender, _tokenId);
-    (bool success, ) = payable(owner).call{value: msg.value}(""); // when funds aren't used
-    require(success, "Transfer failed"); // when funds aren't used
+    (bool success, ) = payable(owner).call{value: msg.value}("");
+    require(success, "Transfer failed");
     emit ItemBought(msg.sender, _nftAddress, _tokenId, msg.value);
   }
 
@@ -174,17 +166,6 @@ contract NftMarketplaceV2 is ReentrancyGuard, Ownable {
     emit CollectionAdded(msg.sender, _nftAddress);
   }
 
-  /// @notice Method for withdrawing earned funds
-  /*
-  function withdrawFunds() external {
-    require(funds[msg.sender] > 0, "No funds to withdraw.");
-    uint256 amountToWithdraw = funds[msg.sender];
-    funds[msg.sender] = 0;
-    (bool success, ) = payable(msg.sender).call{value: amountToWithdraw}("");
-    require(success, "Transfer failed");
-  }
-  */
-
   /// @notice Method for changing the listing fee
   function setListingFee(uint256 _newFee) external onlyOwner {
     require(_newFee > 0, "Fee should be above zero.");