Fix blacklist regex syntax errors

[fson]

Summary

On Windows with Node.js v12.x.x, Metro crashes with

SyntaxError: Invalid regular expression: /(.*\\__fixtures__\\.*|node_modules[\\\]react[\\\]dist[\\\].*|website\\node_modules\\.*|heapCapture\\bundle\.js|.*\\__tests__\\.*)$/: Unterminated character class

This has been reported in #453, react/react-native#26829, react/react-native#26969, react/react-native#26878, react/react-native#26598, expo/expo-cli#1147 and expo/expo-cli#1074.

There are a few open pull requests attempting to fix this same issue:

• Changed sharedBlacklist RegExp due to a bug with Node 12.11.0 #464
• Fixing Regex Bug in Node.js v12.11.0+ on Windows and improve security with npm audit fix -force #461
• Fatal Error in REGEX Scape fixed in blacklist.js #458
• Fix regex scape #453 #454

However, none of the existing PRs address the root cause of this error: the escapeRegExp function in blacklist.js tries to convert regular expressions to be agnostic to the path separator ("/" or "\"), but turns some valid regular expressions to invalid syntax.

The error was is this line:
https://github.com/facebook/metro/blob/142348f5345e40ce2075fc7f9dfa30c5d31fee2a/packages/metro-config/src/defaults/blacklist.js#L28
When given a regular expression, such as /node_modules[/\\]react[/\\]dist[/\\].*/, on Windows where path.sep is \ (which is also an escape character in regular expressions), this gets turned into /node_modules[\\\]react[\\\]dist[\\\].*/, resulting in the Unterminated character class error.

Automatically replacing [/] with [\] is an error, as is replacing [\/] with [\\], because in both of these cases the backslash before the end of character class "]" escapes it, and the character class becomes unterminated. Therefore, this PR changes the code to look for both escaped forward slash \/ and forward slash /, and always replace them with the escaped version (\/ or \\, depending on the platform).

This fixes #453.

Test plan

Added a test case that exercises the code with both \ and / as path separators.

[codecov-io]

Codecov Report

Merging #468 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #468   +/-   ##
=======================================
  Coverage   84.43%   84.43%           
=======================================
  Files         173      173           
  Lines        5764     5764           
  Branches      949      949           
=======================================
  Hits         4867     4867           
  Misses        794      794           
  Partials      103      103

Impacted Files	Coverage Δ
packages/metro-config/src/defaults/blacklist.js	60% <ø> (ø)	⬆️

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[cpojer]

Thank you!

[facebook-github-bot]

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

[facebook-github-bot]

@cpojer has imported this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[facebook-github-bot]

@cpojer merged this pull request in 7c6f30b.

[liudonghua123]

I found the regexp.source changed from node v12.11.0, maybe the new v8 engine caused.
see more on https://github.com/nodejs/node/releases/tag/v12.11.0.

D:\code\react-native>nvm use 12.10.0
Now using node v12.10.0 (64-bit)

D:\code\react-native>node
Welcome to Node.js v12.10.0.
Type ".help" for more information.
> /node_modules[/\\]react[/\\]dist[/\\].*/.source
'node_modules[\\/\\\\]react[\\/\\\\]dist[\\/\\\\].*'
> /node_modules[/\\]react[/\\]dist[/\\].*/.source.replace(/\//g, path.sep)
'node_modules[\\\\\\\\]react[\\\\\\\\]dist[\\\\\\\\].*'
>
(To exit, press ^C again or ^D or type .exit)
>

D:\code\react-native>nvm use 12.11.0
Now using node v12.11.0 (64-bit)

D:\code\react-native>node
Welcome to Node.js v12.11.0.
Type ".help" for more information.
> /node_modules[/\\]react[/\\]dist[/\\].*/.source
'node_modules[/\\\\]react[/\\\\]dist[/\\\\].*'
> /node_modules[/\\]react[/\\]dist[/\\].*/.source.replace(/\//g, path.sep)
'node_modules[\\\\\\]react[\\\\\\]dist[\\\\\\].*'
>
(To exit, press ^C again or ^D or type .exit)
>

D:\code\react-native>nvm use 12.13.0
Now using node v12.13.0 (64-bit)

D:\code\react-native>node
Welcome to Node.js v12.13.0.
Type ".help" for more information.
> /node_modules[/\\]react[/\\]dist[/\\].*/.source
'node_modules[/\\\\]react[/\\\\]dist[/\\\\].*'
> /node_modules[/\\]react[/\\]dist[/\\].*/.source.replace(/\//g, path.sep)
'node_modules[\\\\\\]react[\\\\\\]dist[\\\\\\].*'
>
(To exit, press ^C again or ^D or type .exit)
>

D:\code\react-native>nvm use 13.3.0
Now using node v13.3.0 (64-bit)

D:\code\react-native>node
Welcome to Node.js v13.3.0.
Type ".help" for more information.
> /node_modules[/\\]react[/\\]dist[/\\].*/.source
'node_modules[/\\\\]react[/\\\\]dist[/\\\\].*'
> /node_modules[/\\]react[/\\]dist[/\\].*/.source.replace(/\//g, path.sep)
'node_modules[\\\\\\]react[\\\\\\]dist[\\\\\\].*'
>