Using both React and test configs clobbers some rules

[exogen]

Just came across this when updating our Formidable & Victory component boilerplates. We potentially need to add an es6-react-test config.

Let's say you want to write React tests, so your .eslintrc-client-test would have something like:

---
extends:
  - "defaults/configurations/walmart/es6-react"
  - "defaults/configurations/walmart/es6-test"
  - ".eslintrc-base"
globals:
  expect: false

The problem is that es6-react and es6-test both extend es6, and so the latter config's es6 extend will undo some of the rules overridden in the former config. (In the above case, no-extra-parens is reverted).

So it seems that for correct behavior you MUST extend only one configuration from this repo at a time – and as a result, we should add es6-react-test (or es6-test-react).

/cc @ryan-roemer @baer

[baer]

Closed in https://github.com/walmartlabs/eslint-config-defaults/releases/tag/7.1.1