Compiling contract code in tests

[0xGh]

Hi there, I want to compile a smart contract code (which has a couple of dependencies) in a test.

The reason for this is that the contract code is a template. So I would like to do something like this:

it('works', async () => {
   const CompiledContract = await compile(getSource(variables));
   const instance = await CompiledContract.new();
   // ..
})

Any pointers?

[0xGh]

Came up with this solution:

const path = require('path');
const fs = require('fs');

const TruffleCompile = require('@truffle/workflow-compile').default;
const TruffleConfig = require('@truffle/config');
const TruffleContract = require('@truffle/contract');

const MyContractSource = require('fs').readFileSync('./contracts/MyContract.sol', 'utf-8');

let truffleConfig = null;
async function compile(source, fileName = 'TestContract') {
  const config = truffleConfig || TruffleConfig.detect();
  if (!truffleConfig) {
    truffleConfig = config;
  }

  const outFile = path.join('contracts', 'mocks', fileName + '.sol');
  fs.writeFileSync(outFile, source);

  if (config._ && config._.length > 0) {
    config.paths = config._.map(specifiedPath => {
      const absolutePath = path.resolve(config.working_directory, specifiedPath);

      if (fs.existsSync(absolutePath)) {
        return absolutePath;
      } else {
        return specifiedPath;
      }
    });
  }

  const compilationOutput = await TruffleCompile.compile(config);

  fs.unlinkSync(outFile);

  const contractArtifact = compilationOutput.compilations[0].contracts.find(
    ({ contractName }) => contractName == fileName,
  );

  if (contractArtifact == null) {
    throw new Error('Contract compiled but not found');
  }

  const contract = TruffleContract(
    contractArtifact.bytecode == 'string'
      ? contractArtifact
      : require('@truffle/compile-common').Shims.NewToLegacy.forContract(contractArtifact),
  );

  contract.setProvider(web3.currentProvider);

  return contract;
}

Probably this solution is not the best because it saves the contract on disk but I am sure it can be improved further later on.

[gnidan]

Whoa you basically got the exact answer I was preparing to write up :)

I'm not sure you need to put the contract on disk... you'll need the NewToLegacy shim definitely, but you should just be able to get the WorkflowCompileResult and massage it for use by the @truffle/contract constructor

[0xGh]

Hi @gnidan thanks for chiming in! Isn't WorkflowCompile.compile scanning the contracts folder to find the contracts that needs compilation? Or do you have a compile version that takes the source contract as input (string), gets the dependencies from disk and compiles my contract with necessary dependencies?

[gnidan]

Hi @gnidan thanks for chiming in! Isn't WorkflowCompile scanning the contracts folder to find the contracts that needs compilation? Or do you have a compile version that takes the source contract as input (string), gets the dependencies from disk and compiles my contract with necessary dependencies?

Oh yeah, I think you want Compile.sources(). It's poorly typed, but hopefully this helps: https://github.com/trufflesuite/truffle/blob/develop/packages/compile-common/src/types.ts#L79 (you might want to see the corresponding implementation in @truffle/workflow-compile or @truffle/compile-solidity, or check out @truffle/fetch-and-compile to see how it does programmatic compilation of sources.)