RecyclableList.InsertAt test added.

Recyclable.CollectionsTests/RecyclableListTests.cs

@@ -278,5 +278,16 @@ namespace Recyclable.CollectionsTests
 			.And.ContainInConsecutiveOrder(testData)
 			.And.BeEquivalentTo(testData);
 		}
+
+		[Fact]
+		public void InsertAtTheBeginningShouldMoveItems()
+		{
+			// Prepare
+			var testData = _testData.ToArray();
+			var list = new RecyclableList<int>();
+
+			// Act
+			_ = Assert.Throws<NotSupportedException>(() => list.Insert(0, -1));
+		}
 	}
 }