Good question—I most likely added it based on some troubleshooting and advice I found online. It looks like Jest uses babel, but the configuration it has doesn't support a specific module structure.

It's almost a year ago, so maybe there are newer versions of tools available, and this configuration is not needed anymore. You can remove the plugin line from the .babelrc, and see if it breaks—if not, removing the plugin & the file should be fine too.

Marcin Wosinek guess it is not required. its running fine even when i remove plugin property