The test setup is a bit confusing with use of Array.prototype.reduce(). If it's helpful to refactor this to make it easier to understand what's going on, I think that would be fine.

indeed this is a bit confusing.
I tried adding async code in the initialValue for the reduce method along with the current one
here

I added this

but got parsing error

@anikethsaha Thanks for working on it 👍

but got parsing error

You should change the parserOptions with ecmaVersion >= 8 ( 8, 9, ..)

thanks a lot @yeonjuan ! it worked like a charm.
(I thought async are supported in es2015 !)

@kaicataldo I added two test cases. Just do let me know if you need to add some more!

@anikethsaha
Thanks for updating the documentation.
Maybe I didn't describe well at the comment before. sorry 😂

what I understood from this test setup is that these cases are invalid cases and these will be converted into valid and invalid cases. right !

What I meant was that the newly added tests should be in the array at the third parameter of ruleTester.run(), not in the second parameter of Array.prototype.reduce().

Because the test cases at the second parameter of Array.prototype.reduce() are not converted into invalid and valid cases.

• the cases newly added are not passed in the second parameter(item) of toValidInvalid(patterns, item)

The current test setup seems to like this:

ruleTester.run("no-empty-function", rule, [
   /* 
    * These elements are the test cases that need to be tested with each option and various invalid, valid form.
    * So these elements are converted into other forms by 'toValidInvalid()'
    */
    ,
]).reduce(toValidInvalid, {
  valid: [
    /*
     * These are always valid. So don't need to be converted  
     * That is the reason why "var foo = () => 0;" is here because it is not an empty function.
     */
    {
        code: "var foo = () => 0;", // it has return value '0'. always valid
        parserOptions: { ecmaVersion: 6 }
     }
   ] 

}));

@yeonjuan yes, the second parameter of reduce should contain valid tests and I kept these two cases in valid array with an option to make them valid (allow). which is ok but its not testing all the cases. it makes sense to put them in the 3rd parameter of ruleTester.run to test all cases of these.

I will change this 👍

• contributing guideline.

. If the pull request addresses an issue, then the issue number should be mentioned at the end.

And it would be nice if we mentioned the issue number in the PR title.

@yeonjuan done 👍

cc @kaicataldo @yeonjuan I added more tests and did the docs changes as request.

Do let me know if anything else needs to be changed!

cc @yeonjuan done

Thanks for contributing to ESLint!