DummyIcon test (#2515)

* DummyIcon test

Also the relevant fixes.

* Unbox this

* 3rd string

* Update Content.Client/GameObjects/Components/Kitchen/MicrowaveVisualizer.cs

Co-authored-by: DrSmugleaf <DrSmugleaf@users.noreply.github.com>

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>
Co-authored-by: DrSmugleaf <DrSmugleaf@users.noreply.github.com>

Content.IntegrationTests/Tests/DummyIconTest.cs

@@ -0,0 +1,35 @@
+#nullable enable
+using System.Linq;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using Robust.Client.GameObjects;
+using Robust.Client.Interfaces.ResourceManagement;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Prototypes;
+
+namespace Content.IntegrationTests.Tests
+{
+    [TestFixture]
+    public class DummyIconTest : ContentIntegrationTest
+    {
+        [Test]
+        public async Task Test()
+        {
+            var client = StartClient();
+            await client.WaitIdleAsync();
+
+            var prototypeManager = client.ResolveDependency<IPrototypeManager>();
+            var resourceCache = client.ResolveDependency<IResourceCache>();
+
+            await client.WaitAssertion(() =>
+            {
+                foreach (var proto in prototypeManager.EnumeratePrototypes<EntityPrototype>())
+                {
+                    if (!proto.Components.ContainsKey("Sprite")) continue;
+
+                    SpriteComponent.GetPrototypeTextures(proto, resourceCache).ToList();
+                }
+            });
+        }
+    }
+}