validate cached guild

tests/guilds/create_guild.ts

@@ -1,4 +1,4 @@
-import { createGuild, delay } from "../../mod.ts";
+import { cache, createGuild, delay } from "../../mod.ts";
 import { defaultTestOptions, tempData } from "../ws/start_bot.ts";
 import { assertEquals, assertExists } from "../deps.ts";
 
@@ -17,6 +17,8 @@ Deno.test({
 
     // Delay the execution by 5 seconds to allow GUILD_CREATE event to be processed
     await delay(5000);
+
+    if (!cache.guilds.has(guild.id)) throw new Error("The guild seemed to be created but it was not cached.");
   },
   ...defaultTestOptions,
 });