commit!

src/ObservableCollections.Unity/Assets/Plugins/ObservableCollections/Runtime/RingBuffer.cs

@@ -157,6 +157,11 @@ namespace ObservableCollections
 
         public RingBufferSpan<T> GetSpan()
         {
+            if (count == 0)
+            {
+                return new RingBufferSpan<T>(Array.Empty<T>(), Array.Empty<T>(), 0);
+            }
+
             var start = head & mask;
             var end = (head + count) & mask;
 
@@ -206,6 +211,8 @@ namespace ObservableCollections
 
         public IEnumerable<T> Reverse()
         {
+            if (count == 0) yield break;
+
             var start = head & mask;
             var end = (head + count) & mask;
 

src/ObservableCollections/RingBuffer.cs

@@ -157,6 +157,11 @@ namespace ObservableCollections
 
         public RingBufferSpan<T> GetSpan()
         {
+            if (count == 0)
+            {
+                return new RingBufferSpan<T>(Array.Empty<T>(), Array.Empty<T>(), 0);
+            }
+
             var start = head & mask;
             var end = (head + count) & mask;
 
@@ -206,6 +211,8 @@ namespace ObservableCollections
 
         public IEnumerable<T> Reverse()
         {
+            if (count == 0) yield break;
+
             var start = head & mask;
             var end = (head + count) & mask;
 

tests/ObservableCollections.Tests/RingBufferTest.cs

@@ -126,6 +126,46 @@ namespace ObservableCollections.Tests
 
         }
 
+        [Fact]
+        public void Iteration()
+        {
+            var empty = new RingBuffer<int>();
+            empty.ToArray().Should().BeEmpty();
+
+
+            for (int i = 0; i < 10; i++)
+            {
+                var buffer = new RingBuffer<int>();
+                for (int j = 0; j < i; j++)
+                {
+                    buffer.AddLast(j);
+                }
+                buffer.ToArray().Should().Equal(Enumerable.Range(0, i).ToArray());
+            }
+
+            for (int i = 0; i < 10; i++)
+            {
+                var buffer = new RingBuffer<int>();
+                for (int j = 0; j < i; j++)
+                {
+                    buffer.AddFirst(j);
+                }
+                buffer.ToArray().Should().Equal(Enumerable.Range(0, i).Reverse().ToArray());
+            }
+        }
+
+        [Fact]
+        public void RandomIteration()
+        {
+            var buffer = new RingBuffer<int>();
+            buffer.AddFirst(10);
+            buffer.AddLast(20);
+            buffer.AddLast(30);
+            buffer.AddFirst(40);
+
+            buffer.ToArray().Should().Equal(40, 10, 20, 30);
+        }
+
         [Fact]
         public void BinarySearchTest()
         {