Fix: [no-duplicate-imports] ignore namespace imports (fixes #12758)

[JoaoDsv]

Prerequisites checklist

• I have read the contributing guidelines.
• The team has reached consensus on the changes proposed in this pull request. If not, I understand that the evaluation process will begin with this pull request and won't be merged until the team has reached consensus.

What is the purpose of this pull request? (put an "X" next to an item)

Solve this issue.

What changes did you make? (Give an overview)

Fix a bug on [no-duplicate-imports] rule.
It shouldn't throw an error when the duplicated import is a namespace import such as import * as Namespace from 'module'

What did you do? Please include the actual source code causing the issue.
Fix a bug on [no-duplicate-imports] rule.

What did you expect to happen?
It shouldn't throw an error when the duplicated import is a namespace import such as import * as namespace from 'module'. Because namespace imports can't be merged.

Example of correct code:

import { anotherValue } from 'parsers';
import * as parsers1 from 'parsers';

What actually happened? Please include the actual, raw output from ESLint.
It was considered as incorrect.

Is there anything you'd like reviewers to focus on?

I'm wondering if it could be helpful to extract isNamespaceImport() function's content inside an util. WDYT?

Transforming it a bit to be more generic, it should look like this:

/**
 * Checks the specifier's type.
 * @param {ASTNode} node A node to check.
 * @param {string} the type of the import we want to check .
 *
 * @returns {boolean} Whether or not the specifier's type matchs the "type" param.
 */
function checkSpecifierType(node, type) {
    return (
        node.specifiers &&
        node.specifiers[0] &&
        node.specifiers[0].type === type 
    );
}

[G-Rath]

This behaviour doesn't fit the heuristic:

an import that can be merged with another is a duplicate of that other.

Namespace imports and named imports can be merged with default imports.

[JoaoDsv]

Thanks for your feedback @G-Rath
I'll rework on it to fit this scenario

[nzakas]

Thanks for putting this pull request together. I think you may have the desired functionality reversed, but you're not too far off.

Don't worry about extracting isNamespaceImport() into a general utility. That's something that can always be done later if we need it.

[nzakas]

@JoaoDsv are you still working on this?

[JoaoDsv]

@nzakas I had no time to work on it since your feedback, but I'd be happy to resume this PR next week if it sounds still relevant (and not too late) for you.

[nzakas]

Not too late at all. Just wanted to be sure we give you a chance to finish up before someone else takes this on. If you’re not able to look at it next week, please let us know.

[nzakas]

@JoaoDsv just checking if are you still working on this? Totally understand if not, just want to be sure.

[nzakas]

It looks like this pull request has been abandoned, so closing.

Note: the issue this PR addresses is still accepted (#12758) so anyone who wants to work on implementing the change may do so and submit a separate PR.