Adding custom style entries to the browser refresh on yarn start

I have added a new entry ‘testing’ to my config.json

{
	"entry": {
		"main": ["./scripts/main.js", "./styles/main.scss"],
		"customizer": ["./scripts/customizer.js"],
		"testing": ["./scripts/empty.js", "./styles/blocks/testing.scss"]
	},
	"publicPath": "/app/themes/guttenberg-theme",
	"devUrl": "https://guttenberg.tank",
	"proxyUrl": "http://localhost:3010",
	"cacheBusting": "[name]_[hash:8]",
	"watch": ["app/**/*.php", "config/**/*.php", "resources/views/**/*.php"]
}

And also added the script to the app/setup.php

 if (is_single()) {
        wp_enqueue_style('sage/testing.css', asset_path('styles/testing.css'), false, null);   
}

How can I make it so that when I run yarn start that it includes changes in the browser refresh made from testing.scss?