jest: Fix configuration of Webpack aliases

[constgen]

If we configure alias to React in Webpack which is required by react-hot-loader the Jest tests fail with an error

Configuration error:

    Could not locate module react mapped as:
    C:\Projects\project\node_modules\react$1.

    Please check your configuration for these entries:
    {
      "moduleNameMapper": {
        "/^react$/": "C:\Projects\project\node_modules\react$1"
      },
      "resolver": undefined
    }

    > 1 | import React from 'react';
        | ^
      2 | import PropTypes from 'prop-types';

To reproduce this we need to add something like that to the Webpack aliases configuration

neutrino.config.resolve.alias.set('react', path.resolve(path.join(projectNodeModulesPath, 'react')))

And import any JSX component in tests.

I am curios why we need this $1 at the end. It only makes sense if the key contains angle brackets () like:

Example from Jest docs

"module_name_(.*)": "<rootDir>/substituted_module_$1.js",
"assets/(.*)": [
      "<rootDir>/images/$1",
      "<rootDir>/photos/$1",
      "<rootDir>/recipes/$1"
]

But we know that we can't ever have angle brackets in the alias key.

The issue can be fixed by removing $1 placeholder

Fixes #1552.

[edmorley]

Good spot! This appears to have been a regression from #487 - where the (.*) group match was removed from the key, but the $1 not also removed from the value:
d3b35a5#diff-204df345f1bb711e711da06c51ea8896

Please could you add a test for this, to prevent further regressions? :-)

[constgen]

Please, review. New tests passed. But unfortunately the build job failed any way. This happens because of incompatibility with the latest ESlint v7 as I understand looking to logs

We really should not accept ESlint 7 in peer dependencies

[edmorley]

We really should not accept ESlint 7 in peer dependencies

ESLint 7 works fine with Neutrino and the tests passed when #1572 was merged. The issue was that ESLint 7.3.0 introduced a breaking change/regression (eslint/eslint/issues/13427), which was now been fixed in 7.3.1. I've retriggered the tests and they now pass.

[edmorley]

Thank you for adding the test :-)