NYC fails to instrument files that have private class methods (#method(){})

Example problem_file.js:

class a {
 #method(){}
}  

nyc --all --cache=false node ./problem_file.js

Expected Behavior

To have the file show up in the listed output.

Observed Behavior

The file does not show up in the list

Troubleshooting steps

If you look at the node_module/.cache you see the file was not actually instrumented.

Environment Information

System: OS: macOS 11.1 CPU: (8) x64 Intel® Core™ i7-4870HQ CPU @ 2.50GHz Memory: 79.61 MB / 16.00 GB Binaries: Node: 14.15.4 - ~/.nvm/versions/node/v14.15.4/bin/node Yarn: 1.22.10 - ~/.nvm/versions/node/v14.15.4/bin/yarn npm: 6.14.10 - ~/.nvm/versions/node/v14.15.4/bin/npm npmPackages: nyc: ^15.1.0 => 15.1.0

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files |       0 |        0 |       0 |       0 |
----------|---------|----------|---------|---------|-------------------

[coreyfarrell]

nyc uses babel internally and does allow for configuration of the parserPlugins that are used. By default this does not include classPrivateMethods as no version of node.js supported that when the latest release was cut. This can be added at https://github.com/istanbuljs/schema/blob/c7747f7a7df8a2b770036834af77dfd0ee445733/index.js#L121-L141 along with any additional babel parser plugins which would be needed to parse code supported directly by any release of node.js. The full list of parser plugins are at https://babeljs.io/docs/en/babel-parser#plugins.

For reference the best way in the mean time to support this for your project is to create nyc.config.cjs:

'use strict';

const {parserPlugins} = require('@istanbuljs/schema').defaults.nyc;
module.exports = {
  parserPlugins: [
    ...parserPlugins,
    'classPrivateMethods'
  ]
};

I’ve created https://github.com/istanbuljs/schema/issues/16 for this since the fix would go in that module.

[coreyfarrell]

babel parser plugins are all built-in, babel does not support 3rd party parser plugins so the complete list for the current version of @babel/parser is at https://babeljs.io/docs/en/babel-parser#plugins. Normal babel plugins are a different thing from parser plugins.

I’ve made a new in-range release of @istanbuljs/schema which sets nyc’s default babel parser features to match the capabilities of node.js 15.8.0.