When I compile my assets with Shakapacker/webpack in my test environment (RAILS_ENV=test), I get the following warning:

WARNING in DefinePlugin
Conflicting values for 'import.meta.env.NODE_ENV'

WARNING in DefinePlugin
Conflicting values for 'process.env.NODE_ENV'

• Shakapacker is defaulting ENV["NODE_ENV"]=test from here, which ends up in DefinePlugin via Webpack's EnvironmentPlugin.

• Webpack defaults options.optimization.nodeEnv to development here (because options.mode=development), which ends up in a second DefinePlugin here

I'm not totally sure what the correct fix might be. For my purposes I'd be happy if NODE_ENV was only ever development/production (ie RAILS_ENV=test would result in NODE_ENV=development), but I can see that might not fit all use cases. For now I can get around it by making sure my test environment always sets NODE_ENV=development before invoking Shakapacker.

If shakapacker wants to explicitly set ENV["NODE_ENV"], I wonder if it ought to set optimization.nodeEnv=false (ref) to avoid the conflicting DefinePlugin values.

Or maybe we could set node_env to a preferred value within each environment in shakapacker.yml ?

Possibly related: #337