```ruby
# TODO: Move to react_on_rails

module ReactOnRails
  module EnsureAssetsCompiled
    def self.check_built_assets
      return if @checked_built_assets
      build_all_assets
    end

    def self.running_webpack_watch?(type)
      running = `pgrep -fl '\\-w \\-\\-config webpack\\.#{type}\\.rails\\.build\\.config\\.js'`
      if running.present?
        puts "Found process, so skipping rebuild => #{running.ai}"
        return true
      end
    end

    def self.build_assets_for_type(type)
      unless running_webpack_watch?(type)
        build_output = `cd client && npm run build:#{type}`
        if build_output =~ /error/i
          fail "Error in building assets!\n#{build_output}"
        else
          puts "Webpack build completed."
        end
      end
    end

    def self.build_all_assets
      build_assets_for_type("client")
      build_assets_for_type("server")
      @checked_built_assets = true
    end

    # Runs on require
    check_built_assets
  end
end
```

Add warning message if the user is testing with webpack running
user
```ruby
# TODO: Move to react_on_rails

module ReactOnRails
  module EnsureAssetsCompiled
    def self.check_built_assets
      return if @checked_built_assets
      build_assets_for_type("client")
      build_assets_for_type("server")
      @checked_built_assets = true
    end

    def self.build_assets_for_type(type)
      unless running_webpack_watch?(type)
        build_output = `cd client && npm run build:#{type}`
        if build_output =~ /error/i
          fail "Error in building assets!\n#{build_output}"
        else
          puts "Webpack build completed."
        end
      end
    end

    def self.running_webpack_watch?(type)
      running = `pgrep -fl '\\-w \\-\\-config webpack\\.#{type}\\.rails\\.build\\.config\\.js'`
      if running.present?
        puts "Found process, so skipping rebuild => #{running.ai}"
        return true
      end
    end

    # Runs on require
    check_built_assets
  end
end
```
assistant