React Native: handlers with parameters break completely

Describe the bug

WIth React Native, using a REST handler that includes a parameter causes all network requests to fail.

Environment

• msw: 0.34.0
• nodejs: 16.3.0
• npm: 7.16.0
• react-native: 0.64.2

To Reproduce

Expected behavior

Mocked network requests to be handled.

Explanation

I’ve created several REST handlers that have been working really well. I’ve subsequently added a new one that has a parameter value in the URL, but this causes all handlers to fail. I’ve tracked the problem down to the getResponse function, in particular it fails trying to find a relevant handler with the error:

SyntaxError: Invalid RegExp: Quantifier has nothing to repeat

To verify it’s only broken in React Native, I’ve created a node test and have verified it is working correctly.

I’ve spent a little while trying to track it down but it has me stumped. If anyone has any any pointers or suggestions on what might be going wrong I’m happy to create a pull request, but at this point I’m lost!

It’s probably worth mentioning that paths with wildcards do work, so in this case:

http://localhost/path/:id will fail

http://localhost/path/* will work

[wwdrew]

Hmm, okay that’s weird. I’ve created a bare-bones repo to demonstrate the bug - and it’s working there just fine. I’m going to have to dig in a little harder to figure out what’s causing it to break in my actual app.

[easybird]

The issue is related to Hermes, and the way they handle regexes:

• https://github.com/facebook/hermes/issues/46
• https://github.com/RocketChat/Rocket.Chat.ReactNative/issues/3371

Solution:

• Issue only occurs in debug mode.
• In debug mode, disabling Hermes in your Podfile and rebuilding the app solves the issue