add index docs

src/ECS/Index/ComponentIndex.cs

@@ -4,6 +4,9 @@
 // ReSharper disable once CheckNamespace
 namespace Friflo.Engine.ECS;
 
+/// <summary>
+/// The index for <see cref="IIndexedComponent{TValue}"/> struct's to search entities with a specific component value in O(1).
+/// </summary>
 public readonly struct ComponentIndex <TIndexedComponent,TValue>
     where TIndexedComponent : struct, IIndexedComponent<TValue>
 {

src/ECS/Index/LinkComponentIndex.cs

@@ -1,9 +1,13 @@
 using System.Collections.Generic;
 using Friflo.Engine.ECS.Index;
+// ReSharper disable UnusedTypeParameter
 
 // ReSharper disable once CheckNamespace
 namespace Friflo.Engine.ECS;
 
+/// <summary>
+/// The index for <see cref="ILinkComponent"/> struct's to search entities with a specific entity in O(1).
+/// </summary>
 public readonly struct LinkComponentIndex <TLinkComponent>
     where TLinkComponent: struct, ILinkComponent
 {

src/Tests/ECS/Index/Test_Index.cs

@@ -120,6 +120,7 @@ public static void Test_Index_indexed_Entity()
         entity2.AddComponent(new LinkComponent { entity = target5 });   AreEqual(2, values.Count);
         entity3.AddComponent(new LinkComponent { entity = target5 });   AreEqual(2, values.Count);
 
+        AreEqual("Count: 2", index.ToString());
         AreEqual(1, index[target4].Count);
         AreEqual(2, index[target5].Count);
 

src/Tests/ECS/Index/Test_IndexedComponent.cs

@@ -97,6 +97,7 @@ public static void Test_IndexedComponent_EntityExtension_Add()
         entity.Add(new IndexedInt { value = 30 });
         AreEqual(1, index[30].Count);
         AreEqual(1, index.Values.Count);
+        AreEqual("Count: 1", index.ToString());
 
         entity.Add(new IndexedInt { value = 31 });
         AreEqual(1, index.Values.Count);