1

I am debugging a bug happened on my truffle solidity test. I can narrow down the problem to an exception happened in the payable modifier.

my contract code:

import "zeppelin-solidity/contracts/token/ERC721/ERC721Token.sol";

contract MyToken is ERC721Token { 
  function MyToken() ERC721Token(NAME, SYMB) public payable {
  }
  function purchase(uint256 _tokenId) public payable {
    // all the code in this function is commented out when I do the test
  }
}

my test code:

MyToken myToken = MyToken(contractAddress);
myToken.purchase.value(1000000000000000000).gas(1000000000000000000)(0);

exception:

     Error: VM Exception while processing transaction: revert
  at Object.InvalidResponse (/usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/errors.js:38:1)
  at /usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/requestmanager.js:86:1
  at /usr/local/lib/node_modules/truffle/build/webpack:/~/truffle-provider/wrapper.js:134:1
  at XMLHttpRequest.request.onreadystatechange (/usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/httpprovider.js:128:1)
  at XMLHttpRequestEventTarget.dispatchEvent (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:64:1)
  at XMLHttpRequest._setReadyState (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:354:1)
  at XMLHttpRequest._onHttpResponseEnd (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:509:1)
  at IncomingMessage.<anonymous> (/usr/local/lib/node_modules/truffle/build/webpack:/~/xhr2/lib/xhr2.js:469:1)
  at endReadableNT (_stream_readable.js:1101:12)
  at process._tickCallback (internal/process/next_tick.js:114:19)
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6
  • Are you sure (I mean, really sure) the contract is deployed at contractAddress and the ABI of MyContract correctly describes it?
    – Rob Hitchens
    Commented Apr 11, 2018 at 0:35
  • Actualy not having payable is equivalent to require(msg.value == 0) and having payable is equibalent to removing that require.
    – Ismael ♦
    Commented Apr 11, 2018 at 2:46
  • Are you testing your code via Solidity? if so the testing contract might need to have some ether in order to make the transaction. To do so add this uint public initialBalance = 1 ether; in your testing contract. truffleframework.com/docs/getting_started/…
    – qbsp
    Commented Apr 11, 2018 at 3:04
  • @RobHitchens Yes, I am. I have an assertion confirm it. Assert.equal(myToken.ownerOf(0), contractAddress, "owner is contractAddress");
    – Wenjing
    Commented Apr 11, 2018 at 18:29
  • Seems mixed up, but hard to be sure out of context. myToken address == contract address == contract owner address. Seems like trying to use the token ABI to instantiate a contract at the owner's wallet address. That probably isn't where it is.
    – Rob Hitchens
    Commented Apr 11, 2018 at 22:50

1 Answer 1

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2

I'm adding the answer since its in the comments above and might be helpful for someone.

The transaction has been reverted because the testing contract has no balance. When you need to test the contact transactions via Solidity the sender is the testing contract. To allow the testing contract to make transactions you need to set the initial balance.

uint public initialBalance = 1 ether; // or any other value

this property must to be added to your testing contract. ref

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