RecyclableLongList.Insert implementation finished. Tests added.

Recyclable.Collections/RecyclableLongList.cs

@@ -837,24 +837,60 @@ namespace Recyclable.Collections
 
 		public void Insert(int index, T item)
 		{
-			if (index > _longCount++ || index < 0)
+			if (index > _longCount || index < 0)
 			{
-				_longCount--;
 				Helpers.ThrowIndexOutOfRangeException($"Argument \"{nameof(index)}\" = {index} is out of range. Expected value between 0 and {_longCount}");
 			}
 
-			if (_capacity < _longCount)
+			if (_capacity < ++_longCount)
 			{
 				_capacity = Helpers.Resize(this, _blockSize, _blockSizePow2BitShift, checked((long)BitOperations.RoundUpToPowerOf2((ulong)_longCount)));
 			}
 
-			if (_longCount > 1)
+			if (index + 1 < _longCount)
 			{
 				Helpers.MakeRoomAndSet(this, index, item);
 			}
 			else
 			{
-				new Span<T>(_memoryBlocks[0])[0] = item;
+				new Span<T>(_memoryBlocks[_nextItemBlockIndex])[_nextItemIndex] = item;
+			}
+
+			if (_nextItemIndex < _blockSizeMinus1)
+			{
+				if (++_nextItemIndex == 1)
+				{
+					_lastBlockWithData++;
+				}
+			}
+			else
+			{
+				_nextItemIndex = 0;
+				_nextItemBlockIndex++;
+			}
+
+			_version++;
+		}
+
+		public void Insert(long index, T item)
+		{
+			if (index > _longCount || index < 0)
+			{
+				Helpers.ThrowIndexOutOfRangeException($"Argument \"{nameof(index)}\" = {index} is out of range. Expected value between 0 and {_longCount}");
+			}
+
+			if (_capacity < ++_longCount)
+			{
+				_capacity = Helpers.Resize(this, _blockSize, _blockSizePow2BitShift, checked((long)BitOperations.RoundUpToPowerOf2((ulong)_longCount)));
+			}
+
+			if (index + 1 < _longCount)
+			{
+				Helpers.MakeRoomAndSet(this, index, item);
+			}
+			else
+			{
+				new Span<T>(_memoryBlocks[_nextItemBlockIndex])[_nextItemIndex] = item;
 			}
 
 			if (_nextItemIndex < _blockSizeMinus1)

Recyclable.CollectionsTests/RecyclableLongListTests.cs

@@ -530,13 +530,19 @@ namespace Recyclable.CollectionsTests
 
 		[Theory]
 		[MemberData(nameof(RecyclableLongListTestData.SourceTargetDataVariants), MemberType = typeof(RecyclableLongListTestData))]
-		public void InsertShouldRaiseNotSupportedException(string testCase, IEnumerable<long> testData, long itemsCount, int targetBlockSize)
+		public void InsertAtTheEndShouldAppend(string testCase, IEnumerable<long> testData, long itemsCount, int targetBlockSize)
 		{
 			// Prepare
 			using var list = new RecyclableLongList<long>(testData, minBlockSize: targetBlockSize);
 
 			// Act
-			_ = Assert.Throws<NotSupportedException>(() => list.Insert(0, -1));
+			list.Insert(itemsCount, -1);
+
+			// Assert
+			list.LongCount.Should().Be(itemsCount + 1);
+			list.LongCount.Should().Be(list.Count);
+			list[list.LongCount - 1].Should().Be(-1);
+
 		}
 
 		[Fact]