This project contains an Ethereum smart contract written in Solidity, which can serve as an auction marketplace for any ERC-721 token.
- An implementation of an ERC721 from Openzeppelin is included in the codebase for the purpose of testing the marketplace contract
- Ether is used as currency for bids.
- All bid amounts are specified in wei.
Contract source files
The following solidity files are included as part of this distribution
contracts\ERC721MarketPlace.sol- The ERC721 market place solidity smart contract.contracts\IERC721.sol- ERC721 Interface spec as per https://eips.ethereum.org/EIPS/eip-721contracts\MusicNFT.sol- Example ERC721 implementation used for testing and demonstrating functionality of ERC721MarketPlace.
Dependenecy versions mentioned here are only for guidance. These are the versions I used while building this.
- Node v16.13.0
- Ganache
- Truffle v5.4.17
- Unzip the given code bundle
- install dependencies
cd nft_marketplace
npm install
cd nft_marketplace
truffle compile
cd nft_marketplace
truffle test
Expected output
Using network 'test'.
Compiling your contracts...
===========================
> Compiling .\contracts\ERC721MarketPlace.sol
> Compiling .\contracts\ERC721MarketPlace.sol
> Compiling .\contracts\IERC721.sol
> Compiling .\contracts\MusicNFT.sol
> Compiling .\contracts\MusicNFT.sol
> Artifacts written to C:\Users\username\AppData\Local\Temp\test--18204-jhU2JKJWXqg3
> Compiled successfully using:
- solc: 0.8.9+commit.e5eed63a.Emscripten.clang
0x8CdaF0CD259887258Bc13a92C0a6dA92698644C0
√ Initial setup - create nfts and sales for test (18245ms)
√ ClaimNft should fail for invalid sale ID (724ms)
√ ClaimNft should fail if sale has not yet ended (204ms)
√ ClaimNft should fail when bids exist, if caller is not the highest bidder (254ms)
√ ClaimNft should fail when no bids exist, if caller is not the sale poster (276ms)
√ Successfully call claimNft when no bids exist (1452ms)
√ Successfully call claimNft when bids exist (2380ms)
Contract: Marketplace contract - bid for sale
√ create sale (6319ms)
√ fail to bid on non-existent sale (194ms)
√ fail to bid on with amount that is less than minimum price (212ms)
√ successful bid (2376ms)
√ fail to bid if price is not higher than previous (363ms)
√ successfull new bid should refund previous highest bidder (1789ms)
√ fail to bid if sale has already expired (2298ms)
√ fail to bid if sale has ended (1879ms)
Contract: Marketplace contract - Sale creation
√ create required NFTs (897ms)
√ fail to create sale if transfer of NFT is not pre-approved to marketplace contract address (256ms)
√ fail to create sale if token ID in sale creation transaction is incorrect (617ms)
√ fail to create sale if seller does not own the NFT (191ms)
√ fail to show sale before it is created (62ms)
√ successfully create sale (855ms)
√ succesfully show created sale (78ms)
Contract: Marketplace contract - end sale
√ Initial setup - create nfts and sales for test (10172ms)
√ ClaimNft should fail if sale has not yet ended
√ Endsale should fail if caller is not the sale poster (193ms)
√ Successfully call endsale (902ms)
√ ClaimNft success should close sale and transfer NFT
√ Endsale should fail if sale has already ended (250ms)
√ Endsale should fail if required time has not yet elapsed (554ms)
29 passing (56s)
1. Start Ganache
Truffle will attempt to connect to local ethereum client with following connection parameters. Please make sure Ganache is up and running before you try running the migration command below.
- host > 127.0.0.1
- port > 7545
- network_id > 5777
2. Run migration
cd nft_marketplace
truffle migrate
Expected output
Starting migrations...
======================
> Network name: 'ganache'
> Network id: 5777
> Block gas limit: 6721975 (0x6691b7)
1_initial_migration.js
======================
Replacing 'MusicNFT'
--------------------
> transaction hash: 0x15fa1a5566bb6d0a22b0dd5def2c01405821501d9d1c904d5fdfa7c0791e5a2f
> Blocks: 0 Seconds: 0
> contract address: 0x706fF9a266D18C72F72C2dB46C907B0B4377547f
> block number: 1
> block timestamp: 1636266406
> account: 0x26395fA99cb4666697d13DB76690cB34Fe284D82
> balance: 99.91170788
> gas used: 4414606 (0x435c8e)
> gas price: 20 gwei
> value sent: 0 ETH
> total cost: 0.08829212 ETH
0x706fF9a266D18C72F72C2dB46C907B0B4377547f
Replacing 'ERC721MarketPlace'
-----------------------------
> transaction hash: 0xdc8539a67458023bcd4dfcaebb2c5779fe29fbec551d1f33557f5e11f430915a
> Blocks: 0 Seconds: 0
> contract address: 0x49829A227cA7f2f9F21829080c509D67E41769A6
> block number: 2
> block timestamp: 1636266408
> account: 0x26395fA99cb4666697d13DB76690cB34Fe284D82
> balance: 99.8809661
> gas used: 1537089 (0x177441)
> gas price: 20 gwei
> value sent: 0 ETH
> total cost: 0.03074178 ETH
> Saving artifacts
-------------------------------------
> Total cost: 0.1190339 ETH
Summary
=======
> Total deployments: 2
> Final cost: 0.1190339 ETH
Patterns used in marketplace contract
Withdrawal pattern - This puts the onus of dev=livery (and expense of gas) on the recipient of the asset. Hence in our contract the beneficairy needs to call a claimBidRefund or claimNft function to claim assets that are due to them. They are not directly sent to the beneficairy as part of some other transaction.
Checks-effects-Interaction - This pattern is used in the contract for ensuring no re-entrancy vulnerabilities exist.
Contract documentation
The ERC721 marketplace contract has been documented with NATSPEC style comments as per the specificiations in Solidity docs
https://docs.soliditylang.org/en/develop/natspec-format.html
Code structure
The style guide mentioned in solidity doc has been adhered to for code structure, naming and documentation.
https://docs.soliditylang.org/en/v0.8.9/style-guide.html
2. Warnings seen during compilation
During compilation you may see a warning that duplicate contract names are found like below
> Duplicate contract names found for ERC165.
> This can cause errors and unknown behavior. Please rename one of your contracts.
> Duplicate contract names found for IERC721.
> This can cause errors and unknown behavior. Please rename one of your contracts.
This is because the IERC721 interface spec included in this bundle has the same names as that used in Openzeppelin (which exists as a dependency) codebase. This presently does not cause any issues, but they can be renamed in our contract as a future step, OR we can directly use the available interface specs from Openzeppelin.
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