[Fix] jsx-indent-props : Apply indentation when operator is used in front of the upper line

[Moong0122]

To apply indentation if there is an operator in front of the line above,
modified lib/rules/jsx-indent-props, and added test case in tests/lib/rules/jsx-indent-props.

PR fixes #647

[xfournet]

There is a regression with this update, as show in this example. At line "key=3" and the next one the linter is now expecting an indent of 6 instead of 4. This is not the case for the next element in the array.
If the first element of the array is commented (the one with the ternary expression) the expected indentation is correctly expected to 4 again.

import React from 'react';

const x = false;

const Test = () => ([
  (x
    ? <div key="1" />
    : <div key="2" />),
  <div
    key="3"
    align="left"
  />,
  <div
    key="4"
    align="left"
  />,
]);

export default Test;

[Moong0122]

@xfournet
First of all, I would like to say thank you for discovering the problem!
The cases I added didn't seem to solve the case you gave me.

@ljharb
I want to add a case, modify the code, and deliver the PR again. Can I create a new issue?

[ljharb]

@Moong0122 sure - no need for an issue tho, if you just want to open a PR directly?

[Moong0122]

@ljharb
In my opinion, some people may have similar errors, so I think it would be better to let them know that the problem is being solved through the issue :)

@xfournet
I'm trying to revise the code again by creating a new issue, can I use the example you told me?

[ljharb]

@Moong0122 hopefully we could solve and release it quickly enough that that wouldn't be a problem :-)

[Moong0122]

@ljharb
yes, then I'll send the PR directly as soon as possible!

[xfournet]

@Moong0122 sure you can freely use/adapt the example as you wish

[bukowskiadam]

We're having this problem now. Using 7.21.3 causes no issues, but the latest one causes us a lot of errors. 👀 Thanks for fixing it in advance!

[danrot]

Just a side question I discovered because of this BC break: I realized that the indent rule that comes with eslint itself also formatted my JSX code as I had it in mind. Does it make sense to keep using that rule then? 🤔

[ljharb]

@danrot yes; eslint's indent rule both doesn't format jsx in all the same ways our rule does. I suggest configuring indent to ignore JSX, as the airbnb config does.