WIP Add solidity-coverage

[jacque006]

Add coverage for contracts via solidity-coverage to help identify areas that need additional tests both now and in the future.

TODO

• Coverage is not reporting statements and lines, may be due to Zero coverage when using hardhat_reset sc-forks/solidity-coverage#574 although I only found one test case which calls hardhat_reset
• Determine if tests involving gas prices will be affected. https://hardhat.org/plugins/hardhat-gas-reporter.html might be a good followup to add so we can keep an eye on it.
• Remove skips/onlys
• Fix failing frontend tests

[cgewecke]

Sorry for the delay debugging this. You're seeing zero-coverage because:

• solidity-coverage modifies your contracts (injecting trace instrumentation) and recompiles them, saving the result to artifacts
• you consume your bytecode from typechain factories in types/

You need to run typechain after solidity-coverage executes it's custom compilation. You can do this using a workflow hook in .solcover.js

With this config

const shell = require('shelljs'); // This is a dep at solidity-coverage, no need to install separately

module.exports = {
    skipFiles: ["./test", "./deployment"],
    onCompileComplete: async function(config){
      shell.exec("typechain --target ethers-v5 './artifacts/contracts/**/!(*.dbg).json'");
    }
};

... you'll see:

[cgewecke]

Oh! Just remembered, there's (at least) one more potential coverage issue. SC doesn't handle hardhat_reset well, because that method completely re-instantiates the provider.

hubble-contracts/test/fast/frontends.test.ts

Line 28 in 7d28e78

await ethers.provider.send("hardhat_reset", []);

It should be possible to achieve the same thing using evm_snapshot and evm_revert without running into problems.

[jacque006]

Thanks @cgewecke ! Things are looking much better:

Still running into some issues with tests involving gas consumption, but I was expecting that from https://github.com/sc-forks/solidity-coverage#usage-notes