When submiting my app for approval should I hard code isTest:false for the billing app plan or use an env var?

When creating a plan using the Manual billing Admin API for my app do I hardcode isTest:false or create an env?

When hard coding isTest:false I dont know how to test the charge on shopify dev, how are the shopify admins able to test this when I submit my app for approval?

When I use the environment variable: NODE_ENV = production on localhost and run “shopify app dev” the isTest gets overridden to true even tho I set NODE_ENV = production. But for some reason on the online Shopify dev shop (not localhost) it stays as the process.env.NODE_ENV === “development” result which is isTest:false because I set NODE_ENV = production. * - Why is this happening?

  if (intent === "subscribe" && (plan === PLAN_BASIC || plan === PLAN_PRO)) {
    try {
      const shopHandle = session.shop.replace(".myshopify.com", "");
      await billing.request({
        plan,
        isTest: process.env.NODE_ENV === "development",
        returnUrl: `https://admin.shopify.com/store/${shopHandle}/apps/${process.env.SHOPIFY_API_KEY}/app/pricing`,
      });
      // The above call redirects, so code below won't run
    } catch (error: any) {
      console.error("[Billing] request failed:", error?.message);
      console.error("[Billing] billingErrors:", JSON.stringify(error?.billingErrors ?? error?.errors ?? null, null, 2));
      throw error;
    }
  }

I submitted my app using the hard coded isTest:false for the app plan and got approved. So it looks like for local development just hard code isTest:true until you push to production then hard code isTest:false for the app plan