Events: Support indexed array attributes in tests

[svenstucki]

The current to.emit().withArgs() matcher does not support indexed (variable length) arrays. Indexed attributes must be fixed size (32 bytes), so solidity stores a hash of the array content. This is not checked for and the comparison in a test fails.

Example contract:

pragma solidity ^0.5.4;

contract Test {
  event Event (bytes a, bytes indexed b);

  function emitEvent() public {
    bytes memory test = abi.encode(0x01);
    emit Event(test, test);
  }
}

Example test case:

import chai from 'chai';
import { createMockProvider, deployContract, getWallets, solidity } from 'ethereum-waffle';

import Test from '../build/Test';

chai.use(solidity);
const { expect } = chai;

describe('Test', () => {
  const provider = createMockProvider();
  const [wallet] = getWallets(provider);

  const packed = '0x0000000000000000000000000000000000000000000000000000000000000001';

  it('Should emit', async () => {
    const t = await deployContract(wallet, Test, []);

    await expect(t.emitEvent())
      .to.emit(t, 'Event')
      .withArgs(packed, packed);
  });
});

The actualArgs.values in matchers.ts line 113 contains the following:

     '0': '0x0000000000000000000000000000000000000000000000000000000000000001',
     '1':
      _Indexed {
        hash: '0xb10e2d527612073b26eecdfd717e6a320cf44b4afac2b0732d9fcbe2b7fa0cf6' },

Which is not unexpected, but the comparison fails for the indexed argument. When passing an object in the test (i.e. { hash: '0xb10...' } instead of the 0x0..01 string), the comparison fails as well.

It would be great to have a simple way to test indexed attributes.

[sz-piotr]

We would gladly merge a PR that adds this functionality!

[zgorizzo69]

@sz-piotr I have a simple PR for that. Can you give me the creds to push a branch ?

[sz-piotr]

@zgorizzo69 You can fork the repository and open a PR this way :)

[wachulski]

Shouldn't this one be closed? @sz-piotr ?

[sz-piotr]

Thanks @wachulski
Closing.
Please note that I am no longer a maintainer and ping @marekkirejczyk in the future.

[wachulski]

Yup, I noticed that @sz-piotr and hence created #467 Thanks.