Make item size scale with stack size (#17623)

* Make stack count affect item size

* and the test, too

* readd this check

* vwoom

* huh

* if you ever read this commit message ping me on discord in #contributors

* changerinos

Content.IntegrationTests/Tests/StackTest.cs

@@ -0,0 +1,42 @@
+using System.Threading.Tasks;
+using Content.Server.Storage.Components;
+using Content.Shared.Item;
+using Content.Shared.Stacks;
+using NUnit.Framework;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Prototypes;
+
+namespace Content.IntegrationTests.Tests;
+
+[TestFixture]
+public sealed class StackTest
+{
+    [Test]
+    public async Task StackCorrectItemSize()
+    {
+        await using var pairTracker = await PoolManager.GetServerClient(new PoolSettings{NoClient = true});
+        var server = pairTracker.Pair.Server;
+
+        var protoManager = server.ResolveDependency<IPrototypeManager>();
+        var compFact = server.ResolveDependency<IComponentFactory>();
+
+        Assert.Multiple(() =>
+        {
+            foreach (var entity in PoolManager.GetEntityPrototypes<StackComponent>(server))
+            {
+                if (!entity.TryGetComponent<StackComponent>(out var stackComponent, compFact) ||
+                    !entity.TryGetComponent<ItemComponent>(out var itemComponent, compFact))
+                    continue;
+
+                if (!protoManager.TryIndex<StackPrototype>(stackComponent.StackTypeId, out var stackProto) ||
+                    stackProto.ItemSize == null)
+                    continue;
+
+                var expectedSize = stackProto.ItemSize * stackComponent.Count;
+                Assert.That(itemComponent.Size, Is.EqualTo(expectedSize), $"Prototype id: {entity.ID} has an item size of {itemComponent.Size} but expected size of {expectedSize}.");
+            }
+        });
+
+        await pairTracker.CleanReturnAsync();
+    }
+}