[jsx-key] Improve and fix false-positives

[silvenon]

Currently only failing tests because I'm new to developing ESLint rules, so it'll take me a couple of days.

I was planning to do it by detecting if the calling method is map. This would apply to Array.prototype.map as well as React.Children.map. Are there any other cases where the rule should be looking for key?

Will fix #320.

[yannickcr]

Currently only failing tests because I'm new to developing ESLint rules, so it'll take me a couple of days.

No problem :)

I was planning to do it by detecting if the calling method is map.

Seems to be a good solution. Right now I don't see any other cases, but I prefer to miss some edge cases than having some false errors.

[benmosher]

I wondered if this would come up. Couldn't imagine any cases for arrow functions in non-iterators when I wrote the rule, but the examples from #320 make sense.

[silvenon]

Updated! Sorry for being insanely late 😅

Valid cases:

• [<App key={0} />, <App key={1} />];
• [1, 2, 3].map(function(x) { return <App key={x} /> });
• [1, 2, 3].map(x => <App key={x} />);
• [1, 2, 3].map(x => { return <App key={x} /> });
• var App = () => <div />;

Invalid cases:

• [<App />];
• [<App {...key} />];
• [<App key={0}/>, <App />];
• [1, 2 ,3].map(function(x) { return <App /> });
• [1, 2 ,3].map(x => <App />);
• [1, 2 ,3].map(x => { return <App /> });

[silvenon]

Note sure why coverage fell, it seems to have fallen in /lib/rules/jsx-pascal-case.js for some reason.

[yannickcr]

Seems due to a missing test for a case in jsx-key https://coveralls.io/files/1701759218#L50

(for jsx-pascal-case, it already had a bad coverage, my fault!)

[silvenon]

Done 😃

[yannickcr]

Merged, thanks :)