Fix HasteImpl Regex

[CaptainNic]

Summary

The jest HasteImpl's pluginNameReducers regex was not properly escaping a backslash, resulting in unintended behavior.

The intent of the code is to strip the .${name} from the end of a filepath, where name is a platform name. The correct regex for that would be ^(.*)\.(myPlat)$, but because the regex is being constructed from a string, the \. is being interpreted as an escaped period, resulting in the regex ^(.*).(myPlat)$. To correct this, the backslash needs to be escaped so it makes it into the regex.

Changelog

[General] [Fixed] - Fix HasteImpl platform name regex

Test Plan

This is a stripped down version of jest/hasteImpl.js for testing. Can also be found at https://codepen.io/anon/pen/wZNovr?editors=0011

const haste = {
  platforms: ['ios', 'android', 'dummy']
};

const oldPluginNameReducers = haste.platforms.map(
  name => [new RegExp(`^(.*)\.(${name})$`), '$1'],
);

const newPluginNameReducers = haste.platforms.map(
  name => [new RegExp(`^(.*)\\.(${name})$`), '$1'],
);

function getHasteName(filePath, sourceCode) {
  console.log(`getHasteName('${filePath}')`);
  
  const oldHasteName = oldPluginNameReducers.reduce(
    (name, [pattern, replacement]) => name.replace(pattern, replacement),
    filePath,
  );
  console.log(`[OLD] ${oldHasteName}`);

  const newHasteName = newPluginNameReducers.reduce(
    (name, [pattern, replacement]) => name.replace(pattern, replacement),
    filePath,
  );
  console.log(`[NEW] ${newHasteName}`);
};

getHasteName('myComponent.ios');
getHasteName('myComponentios');

getHasteName('myComponent.dummy');
getHasteName('myComponent.ddummy');

Output:

getHasteName('myComponent.ios')
[OLD] myComponent
[NEW] myComponent
getHasteName('myComponentios')
[OLD] myComponen
[NEW] myComponentios
getHasteName('myComponent.dummy')
[OLD] myComponent
[NEW] myComponent
getHasteName('myComponent.ddummy')
[OLD] myComponent.
[NEW] myComponent.ddummy

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[cpojer]

Thank you @CaptainNic. Do you mind signing the CLA so I can merge this PR?

[CaptainNic]

@cpojer I'm working on figuring out the CLA issue, I was under the assumption that I was already covered under my company's CLA.

[cpojer]

You may need to talk to somebody at your company to get yourself added. I'm assuming @matthargett will be able to help you out :)

[matthargett]

@cpojer @hramos Joel at FB emailed back and said the CLA list was updated. Please let us know if there's anything else we need to do to get this merged. Thanks!

[hramos]

I tried to merge this, but the import tool is unable to find a valid CLA on file. I just looked around our CLA tool and could not find @CaptainNic listed in the CLA. Let me follow up internally and see what's up.

[facebook-github-bot]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Facebook open source project. Thanks!

[facebook-github-bot]

@hramos is landing this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[react-native-bot]

This pull request was successfully merged by @CaptainNic in 28e0de0.

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