fix: Upload file size limit (#2313)

test/Discord.Net.Tests.Unit/GuildHelperTests.cs

@@ -0,0 +1,25 @@
+using Discord.Rest;
+using FluentAssertions;
+using Moq;
+using System;
+using Xunit;
+
+namespace Discord;
+
+public class GuildHelperTests
+{
+    [Theory]
+    [InlineData(PremiumTier.None, 8)]
+    [InlineData(PremiumTier.Tier1, 8)]
+    [InlineData(PremiumTier.Tier2, 50)]
+    [InlineData(PremiumTier.Tier3, 100)]
+    public void GetUploadLimit(PremiumTier tier, ulong factor)
+    {
+        var guild = Mock.Of<IGuild>(g => g.PremiumTier == tier);
+        var expected = factor * (ulong)Math.Pow(2, 20);
+
+        var actual = GuildHelper.GetUploadLimit(guild);
+
+        actual.Should().Be(expected);
+    }
+}