feat: add method isFileConfigured

[fasttime]

This PR adds a method isFileConfigured to ConfigArray, to determine if a file has matching configuration or not. This could be used in ESLint to provide a better message for ignored files that don't have a matching configuration.

Refs eslint/eslint#18263

[fasttime]

This method doesn't need to be public, it could be converted into a local function.

[fasttime]

I've added assertions for isFileConfigured after those for isFileIgnored, because in ESLint isFileConfigured will be called when isFileIgnored returns true. I think this makes more sense than calling isFileConfigured alone. Alternatively, we could duplicate some test cases to keep the assertions separated.

[nzakas]

Does isExplicitMatch() already solve this problem?

[fasttime]

Does isExplicitMatch() already solve this problem?

I tried that but it breaks the tests in ESLint. It looks like ignoreswith glob patterns are not considered as matches:

configs = new ConfigArray([
    {
        ignores: ['**/bar.*']
    },
    {
        rules: { semi: 'error' }
    }
]);

configs.normalizeSync();

console.log(configs.isFileIgnored('bar.txt')); // true
console.log(configs.isExplicitMatch('bar.txt')); // false
console.log(configs.isFileConfigured('bar.txt')); // true

[mdjermanovic]

If the file is ignored by ignore patterns, this returns true regardless of whether or not it has a matching config?

[fasttime]

Yes. This is technically okay, because either way the error message "File ignored because of a matching ignore pattern." does apply. But maybe the method could have a more descriptive name?

[mdjermanovic]

Perhaps we could change the return type of getConfig()? Instead of returning config directly, it could return a { config } object with an additional property that would indicate why is config undefined if that's the case.

[fasttime]

That's an interesting idea, it would be a breaking change though.

[mdjermanovic]

Note: there's a functional difference between isExplicitMatch() and looking for explicit matches inside getConfig().

isExplicitMatch() checks if there's at least one config object whose files match. getConfig() does the same, but additionally at least one of the matching patterns must not end with /* or /**.

const configs1 = new ConfigArray([
    {
        files: ["foo/*.txt"]
    }
]);

configs1.normalizeSync();

console.log(configs1.getConfig('foo/bar.txt')); // {}
console.log(configs1.isFileIgnored('foo/bar.txt')); // false
console.log(configs1.isExplicitMatch('foo/bar.txt')); // true

const configs2 = new ConfigArray([
    {
        files: ["foo/*"]
    }
]);

configs2.normalizeSync();

console.log(configs2.getConfig('foo/bar.txt')); // undefined
console.log(configs2.isFileIgnored('foo/bar.txt')); // true
console.log(configs2.isExplicitMatch('foo/bar.txt')); // true!

[nzakas]

Let's move this over to https://github.com/eslint/rewrite. I'd like to start using the official ESLint version going forward.

[fasttime]

I've created a PR in the rewrite repo: eslint/rewrite#7