fix: Do not show Errors from reading directories

[hyperupcall]

PR Checklist

• Addresses an existing issue: fixes --comments throws EISDir when a directory is specified in TSConfig include #1720
• That issue was marked as status: accepting prs

Overview

If a tsconfig.json contains something like the following:

{
    "include": ["cool"]
}

Then, an error shows up, for example, when using --comments:

✨ 143 rules replaced with their ESLint equivalents. ✨

⚡ 1 new package is required for this ESLint configuration. ⚡
  npm install eslint-config-prettier --save-dev
❌ 1 error running tslint-to-eslint: ❌
  Error: EISDIR: illegal operation on a directory, read

According to the TypeScript docs, a directory entry for include is valid:

If the last path segment in a pattern does not contain a file extension or wildcard charater, then it is treated as a directory, and files with supported extensions inside that directory are included (e.g. .ts, .tsx, and .d.ts by default, with .js and .jsx if allowJs is set to true).

This fixes that case.

[JoshuaKGoldberg]

This works well (yay! thanks!) but I think I'd rather have the issue fixed closer to its source. What do you think?

I'm not against merging as-is if you think what's currently in the PR is a better approach, especially since this repo is old and relatively inactive.

[JoshuaKGoldberg]

[Structure] I actually think the approach here isn't what I'd prefer. collectCommentFileNames is taking in a typescriptConfiguration that looks like:

{
  "compilerOptions": { "target": "es3" },
  "files": ["./cool/index.ts"],
  "include": ["cool"]
}

...but with an output commentFileNames like:

{
  exclude: undefined,
  include: [ './cool/index.ts', 'cool' ]
}

(note that the original TSConfig that made that is just { "include": ["cool"] }.

I think the right approach to fix this earlier in the system would be to have collectCommentFileNames filter out directories from its output. Or maybe just not use the "include" at all, if files has the full list of files?

What do you think?

[hyperupcall]

That sounds good! I have changed things so now collectCommentFileNames handles the filtering of directories. Sorry about the slow response/changes

[JoshuaKGoldberg]

Swell, thanks! This is looking great - and I appreciate you refactoring the internals. 🙌

I'll apply a couple of nits that honestly don't really change much.

[JoshuaKGoldberg]

Nit: could one-line this if you really wanted 😄

Suggested change

	.map((isDirectory, i) => {
	if (isDirectory) {
	return null;
	}
	return includeList[i];
	})
	.map((isDirectory, i) => !isDirectory && includeList[i])

[JoshuaKGoldberg]

Oh, I don't have permissions to modify your fork. No worries - it's just nits.

[JoshuaKGoldberg]

Published in tslint-to-eslint-config@2.14.1. Thanks @hyperupcall! 🥳