Nyc on ESM Node.js 13 (no babel)

Does nyc work with ESM and Node.js 13 without babel?

I followed the steps from https://github.com/avajs/ava/blob/master/docs/recipes/code-coverage.md

My config from package.json is

"scripts": {
    "test": "ava",
    "coverage": "nyc ava"
},
"ava": {
    "files": [
      "src/test/**/*.spec.js"
    ],
    "require": [
      "./src/test/_setup-browser-env.js"
    ],
    "verbose": true
  }

When I run the coverage script I get this:

I don’t use babel, and imports are done with import not require. I’m on the latest versions of node.js, ava, nyc

[coreyfarrell]

nyc does not yet support coverage of node.js native ESM. It will take some time as node.js has just created API’s to make this possible though they are still experimental and subject to breakage. I’m working on creating an @istanbuljs/esm-loader-hook module that could be used as NODE_OPTIONS='--experimental-loader @istanbuljs/esm-loader-hook' nyc mocha, I’ll post here when I have updates for that. nyc won’t handle this transparently until the loader hook API’s are less experimental.

FWIW it looks like the currently available ESM transform hook is available in node.js ^12.16.0 || >=13.7.0. The minimum version could increase if additional breaking changes occur.

[brettz9]

c8 is working for me with "type": "module".