extension default values are not correct in documentation

[armingjazi]

to reproduce

https://github.com/tetrohed/nyc_react_coverage

Expected Behavior

all extensions mentioned in the documentation are picked up by nyc instrument

Observed Behavior

have to explicitly set extension: ['.js', '.jsx'] for 'jsx' to be picked up by the instrumenter

NOTE: the repo is setup with everything to reproduce, just remove extension: ['.js', '.jsx'] from nyc.config.js and run yarn run coverage you can see the file test.jsx is not present in insrumented folder

[Avaq]

I'm having the same issue with the .mjs extension.

Given:

• src/
  • index.mjs: export default 42

I expect the following two scripts to produce the same result:

nyc --all -- node -p '"tests pass"'

nyc --all --extension .mjs -- node -p '"tests pass"'

But the first script produces:

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

Whereas the second script produces:

internal/modules/cjs/loader.js:821
  throw new ERR_REQUIRE_ESM(filename);
  ^

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module

---

Note that the only thing I changed was the --extension flag, to add .mjs which is supposedly included by default. Since .mjs is in the default extension list, both scripts should have thrown the observed ERR_REQUIRE_ESM exception.

[Avaq]

I also just noticed that nyc --help shows an empty list as the default value for --extension.

[coreyfarrell]

The README.md on github.com reflects the current state of master (what will become v15). Current release of nyc is 14.1.1, to read the README.md for the current release it's best to go to npmjs.com. See https://www.npmjs.com/package/nyc#common-configuration-options, in nyc 14.1.1 only .js files are instrumented by default. The additional extensions will be a feature of the next major release. You can monitor progress for the new release at #1104.

@Avaq please also note that native node.js ESM implementation does not support nyc. The native ESM implementation does not provide any hooks for transpiling code, so for nyc to work with native ESM you would need to pre-instrument all code. I hope the node.js team fixes this as it will effectively make @babel/register impossible to implement for native ESM. If you are working with native ESM you might want to check out c8.