added B2ArenaAllocatorTypedTests

Author: ikpil

src/Box2D.NET/B2ArenaAllocators.cs

@@ -35,7 +35,7 @@ public static void b2DestroyArenaAllocator(B2ArenaAllocator allocator)
             allocatorImpl.allocation = 0;
             allocatorImpl.maxAllocation = 0;
             allocatorImpl.index = 0;
-            allocatorImpl.entries = b2Array_Create<B2ArenaEntry<T>>(32);
+            allocatorImpl.entries = b2Array_Create<B2ArenaEntry<T>>(capacity);
             return allocatorImpl;
         }
 

src/Box2D.NET/B2Worlds.cs

@@ -140,7 +140,7 @@ public static B2WorldId b2CreateWorld(ref B2WorldDef def)
             world.generation = generation;
             world.inUse = true;
 
-            world.arena = b2CreateArenaAllocator(2048);
+            world.arena = b2CreateArenaAllocator(256);
             b2CreateBroadPhase(ref world.broadPhase);
             b2CreateGraph(ref world.constraintGraph, 16);
 

test/Box2D.NET.Test/B2ArenaAllocatorTypedTests.cs

@@ -0,0 +1,68 @@
+using NUnit.Framework;
+using static Box2D.NET.B2ArenaAllocators;
+
+namespace Box2D.NET.Test;
+
+public class B2ArenaAllocatorTypedTests
+{
+    [Test]
+    public void Constructor_InitializesCorrectly()
+    {
+        B2ArenaAllocatorTyped<int> alloc = b2CreateArenaAllocator<int>(10);
+        Assert.That(alloc.capacity, Is.EqualTo(10));
+        Assert.That(alloc.data.Array, Is.Not.Null);
+        Assert.That(alloc.data.Count, Is.EqualTo(10));
+        Assert.That(alloc.index, Is.EqualTo(0));
+        Assert.That(alloc.allocation, Is.EqualTo(0));
+        Assert.That(alloc.maxAllocation, Is.EqualTo(0));
+        Assert.That(alloc.entries.data, Is.Not.Null);
+        Assert.That(alloc.entries.count, Is.EqualTo(0));
+        Assert.That(alloc.entries.capacity, Is.EqualTo(10));
+    }
+
+    [Test]
+    public void Grow_IncreasesCapacityWhenMaxAllocationExceedsCurrent()
+    {
+        B2ArenaAllocatorTyped<int> alloc = b2CreateArenaAllocator<int>(10);
+
+        alloc.maxAllocation = 15;
+        int oldCapacity = alloc.capacity;
+        int newCapacity = alloc.Grow();
+
+        Assert.That(newCapacity, Is.GreaterThan(oldCapacity));
+        Assert.That(newCapacity, Is.EqualTo(15 + 15 / 2)); // Check the growth factor
+        Assert.That(alloc.data.Count, Is.EqualTo(newCapacity));
+        Assert.That(alloc.allocation, Is.EqualTo(0)); // Allocation should be 0 before grow
+    }
+
+    [Test]
+    public void Grow_DoesNotIncreaseCapacityWhenMaxAllocationIsWithinCurrent()
+    {
+        B2ArenaAllocatorTyped<int> alloc = b2CreateArenaAllocator<int>(10);
+
+        alloc.maxAllocation = 5;
+        int oldCapacity = alloc.capacity;
+        int newCapacity = alloc.Grow();
+
+        Assert.That(newCapacity, Is.EqualTo(oldCapacity));
+        Assert.That(alloc.data.Count, Is.EqualTo(newCapacity));
+        Assert.That(alloc.allocation, Is.EqualTo(0)); // Allocation should be 0 before grow
+    }
+
+    [Test]
+    public void Destroy_ReleasesResourcesAndResetsProperties()
+    {
+        B2ArenaAllocatorTyped<int> alloc = b2CreateArenaAllocator<int>(10);
+
+        alloc.Destroy();
+
+        Assert.That(alloc.data.Array, Is.Null);
+        Assert.That(alloc.capacity, Is.EqualTo(0));
+        Assert.That(alloc.index, Is.EqualTo(0));
+        Assert.That(alloc.allocation, Is.EqualTo(0));
+        Assert.That(alloc.maxAllocation, Is.EqualTo(0));
+        Assert.That(alloc.entries.data, Is.Null);
+        Assert.That(alloc.entries.count, Is.EqualTo(0));
+        Assert.That(alloc.entries.capacity, Is.EqualTo(0));
+    }
+}