add acceptance tests for cryptoTransfer function

[lukelee-sl]

Signed-off-by: lukelee-sl [email protected]

Description:
hashgraph/hedera-services#3758

The issue referenced above in hedera-services describes several scenarios where using the cryptoTransfer function fails.

Currently, cryptoTransfer succeeds only when the token type being transferred is of homogenous (fungible -> fungible or nft -> nft). Also there is no support for sending hbars as one of the legs of the transfer.

Added several acceptance tests to show use cases where the function succeeds and also when it fails due to heterogeneous token types.

Related issue(s):
hashgraph/hedera-services#3758

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[codecov-commenter]

Codecov Report

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[lukelee-sl]

Here are some results after some exploration.

• In services code there is a checks that ensures that fungibles transfers add up to zero.
• The solidity cryptoTransfer function takes IHederaTokenService.TokenTransferList[] as an argument.
  • TokenTransferList is a struct that contains both and array of AccountAmount (for fungible tokens) and an array of NftTransfer (for NFT). A user could take this to mean that a transfer of heterogeneous types of tokens is possible but services code seems to indicate that this is not possible.
• In my test - homogeneous transfers using crytoTransfer worked
• but heterogeneous transfers failed (as expected).
• I attempted to swap NFT tokens in two separate accounts in a single call and was not successful.
• Also attempted to transfer tokens from a wallet after it was given an allowance but a separate account and was not successful.
• Possible future feature improvements
  • Allow for heterogeneous token type cryptoTransfer
  • Allow HBARs to be transferred as part of the cryptoTransfer

[Nana-EC]

Some suggestions

[stoqnkpL]

There are a couple of problems with the setup:

1. The HTS precompiled contract function cryptoTransfer(TokenTransferList[] memory tokenTransfers) does not support transfers using allowances, it was never designed to. Currently, the only way to make a transfer using allowances through the precompile is to use the redirect functions transferFrom:
   IERC20(token).transferFrom(sender, recipient, amount);
IERC721(token).transferFrom(from, to, tokenId);

I'm not sure why the transferFrom functions were not exposed to HTS precompile top-level like the other functions from ERC20 and ERC721 were with PR3638. In any case, the cryptoTransfer function will not work with allowances.

2. Transfers of HBars via cryptoTransfer is also not supported, only transfers of Fungible tokens and NFTs.

For context, we have existing EETs covering the transfer of tokens (including mixing fungible and nfts) via cryptoTransfer here.
We have existing EETs covering the transferFrom ERC redirect functions here.

[Nana-EC]

LG

[sonarqubecloud]

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