Support --fix-dry-run option in programmatic API

[jopemachine]

--fix-dry-run option looks like it is available only through CLI.

I'm wondering if supporting this flag in programmatic API is possible.

I think it would be useful to use this option in eslint wrapper libraries like xo (Ref: xojs/xo#663)

References

• eslint's programmatic API
  https://eslint.org/docs/developer-guide/nodejs-api#parameters

• eslint's CLI API
  https://eslint.org/docs/user-guide/command-line-interface#--fix-dry-run

[mdjermanovic]

Can you elaborate more on what would be the functionality of this flag in ESLint API?

Linting and saving the changes are already two separate steps:

eslint/lib/cli.js

Lines 295 to 307 in ee69cd3

	if (useStdin) {
	results = await engine.lintText(text, {
	filePath: options.stdinFilename,
	warnIgnored: true
	});
	} else {
	results = await engine.lintFiles(files);
	}
	if (options.fix) {
	debug("Fix mode enabled - applying fixes");
	await ESLint.outputFixes(results);
	}

• eslint --fix calls eslint.lintFiles, and then ESLint.outputFixes.
• eslint --fix-dry-run only calls eslint.lintFiles.

If you want to get the fixed versions (with the remaining unfixable problems) without modifying the files, you can just call eslint.lintFiles.

[jopemachine]

I didn't noticed CLI's fixDryRun option is translated to fix option.
I think I can just pass fix: true to ESLint's constructor option and call eslint.lintFiles to fixDryRun.
I appreciate your insightful answer.