Solidity-coverage: "TypeError: Cannot read property 'length' of undefined" on MetaCoin truffle box

[diega]

Hi!
I'm unable to test coverage on the MetaCoin Truffle sample project. Here are the steps to reproduce

$ mkdir MetaCoin
$ cd MetaCoin
$ truffle unbox metacoin
[...]
$ vim truffle-config.js # this is for adding the solidity-coverage plugin
$ npm install --save-dev solidity-coverage
[...]
$ truffle run coverage
- Fetching solc version list from solc-bin. Attempt #1

> Using Truffle library from global node_modules.

> server:            http://127.0.0.1:8555
> truffle:           v5.1.42
> ganache-core:      v2.11.2
> solidity-coverage: v0.7.11

Network Info
============
> id:      *
> port:    8555
> network: soliditycoverage


Instrumenting for coverage...
=============================

> ConvertLib.sol
> MetaCoin.sol

Coverage skipped for:
=====================

> Migrations.sol

Compiling your contracts...
===========================
> Compiling ./.coverage_contracts/ConvertLib.sol
> Compiling ./.coverage_contracts/MetaCoin.sol
> Compiling ./.coverage_contracts/Migrations.sol
TypeError: Cannot read property 'length' of undefined
TypeError: Cannot read property 'length' of undefined

/Users/diegoll/.config/truffle/compilers/node_modules/soljson-v0.5.16+commit.9c3226ce.js:1
[...]
abort(TypeError: Cannot read property 'length' of undefined). Build with -s ASSERTIONS=1 for more info.
(Use `node --trace-uncaught ...` to show where the exception was thrown)

[cgewecke]

Hi @diega I wasn't able to reproduce this.

I ran:

npm install --save-dev [email protected]
npm install --save-dev solidity-coverage
truffle unbox metacoin --force

My system:

• MacOSX
• Node v12.16.0

...and got the output below. Do you see any relevant differences between these?

Users-MacBook-Air:tr-sc cgewecke$ npx truffle run coverage

> Using Truffle library from local node_modules.

> server:            http://127.0.0.1:8555
> truffle:           v5.1.42
> ganache-core:      v2.11.2
> solidity-coverage: v0.7.11

Network Info
============
> id:      *
> port:    8555
> network: soliditycoverage


Instrumenting for coverage...
=============================

> ConvertLib.sol
> MetaCoin.sol

Coverage skipped for:
=====================

> Migrations.sol

Compiling your contracts...
===========================
> Compiling ./.coverage_contracts/ConvertLib.sol
> Compiling ./.coverage_contracts/MetaCoin.sol
> Compiling ./.coverage_contracts/Migrations.sol
> Artifacts written to /Users/cgewecke/code/tr-sc/.coverage_artifacts/contracts
> Compiled successfully using:
   - solc: 0.5.16+commit.9c3226ce.Emscripten.clang

⚠️  This plugin cannot run Truffle's native solidity tests: 1 test(s) will be skipped.


Compiling your contracts...
===========================
> Everything is up to date, there is nothing to compile.



  Contract: MetaCoin
    ✓ should put 10000 MetaCoin in the first account (56ms)
    ✓ should call a function that depends on a linked library (102ms)
    ✓ should send coin correctly (245ms)


  3 passing (466ms)

-----------------|----------|----------|----------|----------|----------------|
File             |  % Stmts | % Branch |  % Funcs |  % Lines |Uncovered Lines |
-----------------|----------|----------|----------|----------|----------------|
 contracts/      |       90 |       50 |      100 |      100 |                |
  ConvertLib.sol |      100 |      100 |      100 |      100 |                |
  MetaCoin.sol   |    88.89 |       50 |      100 |      100 |                |
-----------------|----------|----------|----------|----------|----------------|
All files        |       90 |       50 |      100 |      100 |                |
-----------------|----------|----------|----------|----------|----------------|

> Istanbul reports written to ./coverage/ and ./coverage.json
> solidity-coverage cleaning up, shutting down ganache server

[diega]

well, the main difference I can see is that mine says
> Using Truffle library from global node_modules.
and yours
> Using Truffle library from local node_modules.

I have truffle installed globally as they recommend and I run all commands through npx (omitted in my original report I don't know why).
Bellow is my global _truffle_ report but that's not the same version shown in the output of the npx truffle run coverage command

$ npx truffle version
- Fetching solc version list from solc-bin. Attempt #1
Truffle v5.1.51 (core: 5.1.51)
Solidity v0.5.16 (solc-js)
Node v12.18.3
Web3.js v1.2.9

having that said, installing truffle locally with the npm install --save-dev [email protected] command that you provided, made it work (also for v5.1.51) and after running that command I can see the same Using Truffle library from local node_modules message as yours

[cgewecke]

Ah yes! Will investigate...

[cgewecke]

I triggered this once but now I can't figure out which combination causes it. When it happened I was running truffle as a global command and also had truffle installed as a local dev dep.

Using a globally installed Truffle (without locally installed Truffle) seems to work with both npx and just truffle.

Perhaps it's something about how Truffle resolves the compiler cache globally / locally? Tbh don't think solidity-coverage will be able to fix this...it might be an obscure bug that affects any plugin that runs the compile command.

[diega]

yes, It's quite possible. I've also found out that npx may have its own version of the libraries installed under ~/.npm/_npx.
Feel free to close this issue, at least I can confirm the workaround of using the locally the --save-dev local version works fine

[cgewecke]

Ok interesting, sounds good. This issue should be easily discoverable for anyone running into the same problem...

Thanks for reporting!