Support testing with an in-process ethereum provider

🧐 Motivation

solidity-coverage is being rewritten so that it has fewer quirks and problems. One element of the new design is that it listens to the ethereumjs-vm opcode step emitter of an in-process ganache instance. In Truffle terms, it runs on a network which looks like:

const ganache = require("ganache-cli")

modules.exports = {
  networks: {
    ganache: {
      provider: ganache.provider(options),
      network_id: "*"
    }
  }
}

Have been testing it on Zeppelin and the only issue is that some GSN tests rely on an oz-gsn utility run in test.sh which connects to ganache-cli as a stand-alone server.

I’m wondering if anyone has any views are about moving away from test.sh towards an in-process provider approach.

I think the main changes this would involve are:

• Putting the accounts keys and balances into their own file so they can be JS required.
• Writing an oz-gsn deploy relay hub test helper that uses an in-process provider
• Launching the tests with ganache.provider by default.

Pros

• Less shell script
• There are interesting tools written to consume the client this way
  • NomicLabs is actively working on some…
  • 0xProject tooling

Cons/Caveats

• It runs a little more slowly. (ganache-core 481 requests info about this)
• Maintaining compatibility with a solution for #355?

Happy to help with PRs etc if this is something you’re interested in.

[cgewecke]

from our discussion here and my understanding of the proposed API it seems to me like it shouldn’t be hard to get ganache-core and the new solidity-coverage bundled together in the fashion I described above. We could do this ourselves if needed.

Ok well you’ve persuaded me this is likely necessary anyway. If you’d like to collaborate in some way I’d be very happy to.

[nventuro]

It seems to me though that it should be possible to have a sort of ‘coverage-node’, a stand-alone process that wraps ganache and exposes the instrument and report functions to the network. I imagine all the truffle plugin does is hook those functions to mocha’s before and after blocks, which could be replicated this way.