Improve tests

DiscordChatExporter.Cli.Tests/Utils/GlobalCache.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace DiscordChatExporter.Cli.Tests.Utils
+{
+    internal static class GlobalCache
+    {
+        private static readonly Dictionary<string, object?> Dictionary = new();
+
+        public static async Task<T> WrapAsync<T>(string key, Func<Task<T>> getAsync)
+        {
+            if (Dictionary.TryGetValue(key, out var value) && value is T existing)
+                return existing;
+
+            var result = await getAsync();
+            Dictionary[key] = result;
+
+            return result;
+        }
+    }
+}