Added InsertAfter extension method.

framework/src/Volo.Abp.Core/System/Collections/Generic/AbpListExtensions.cs

@@ -32,6 +32,18 @@ namespace System.Collections.Generic
             source.Insert(source.Count, item);
         }
 
+        public static void InsertAfter<T>(this IList<T> source, T existingItem, T item)
+        {
+            var index = source.IndexOf(existingItem);
+            if (index < 0)
+            {
+                source.AddFirst(item);
+                return;
+            }
+
+            source.Insert(index + 1, item);
+        }
+
         public static void InsertAfter<T>(this IList<T> source, Predicate<T> selector, T item)
         {
             var index = source.FindIndex(selector);
@@ -44,6 +56,17 @@ namespace System.Collections.Generic
             source.Insert(index + 1, item);
         }
 
+        public static void InsertBefore<T>(this IList<T> source, T existingItem, T item)
+        {
+            var index = source.IndexOf(existingItem);
+            if (index < 0)
+            {
+                source.AddLast(item);
+                return;
+            }
+
+            source.Insert(index, item);
+        }
 
         public static void InsertBefore<T>(this IList<T> source, Predicate<T> selector, T item)
         {

framework/test/Volo.Abp.Core.Tests/System/Collections/Generic/AbpListExtensions_Tests.cs

@@ -11,6 +11,29 @@ namespace System.Collections.Generic
         {
             var list = Enumerable.Range(1, 3).ToList();
 
+            list.InsertAfter(2, 42);
+
+            list.Count.ShouldBe(4);
+            list[0].ShouldBe(1);
+            list[1].ShouldBe(2);
+            list[2].ShouldBe(42);
+            list[3].ShouldBe(3);
+
+            list.InsertAfter(3, 43);
+
+            list.Count.ShouldBe(5);
+            list[0].ShouldBe(1);
+            list[1].ShouldBe(2);
+            list[2].ShouldBe(42);
+            list[3].ShouldBe(3);
+            list[4].ShouldBe(43);
+        }
+
+        [Fact]
+        public void InsertAfter_With_Predicate()
+        {
+            var list = Enumerable.Range(1, 3).ToList();
+
             list.InsertAfter(i => i == 2, 42);
 
             list.Count.ShouldBe(4);
@@ -30,7 +53,7 @@ namespace System.Collections.Generic
         }
 
         [Fact]
-        public void InsertAfter_Should_Insert_To_First_If_Not_Found()
+        public void InsertAfter_With_Predicate_Should_Insert_To_First_If_Not_Found()
         {
             var list = Enumerable.Range(1, 3).ToList();
 
@@ -48,6 +71,29 @@ namespace System.Collections.Generic
         {
             var list = Enumerable.Range(1, 3).ToList();
 
+            list.InsertBefore(2, 42);
+
+            list.Count.ShouldBe(4);
+            list[0].ShouldBe(1);
+            list[1].ShouldBe(42);
+            list[2].ShouldBe(2);
+            list[3].ShouldBe(3);
+
+            list.InsertBefore(1, 43);
+
+            list.Count.ShouldBe(5);
+            list[0].ShouldBe(43);
+            list[1].ShouldBe(1);
+            list[2].ShouldBe(42);
+            list[3].ShouldBe(2);
+            list[4].ShouldBe(3);
+        }
+
+        [Fact]
+        public void InsertBefore_With_Predicate()
+        {
+            var list = Enumerable.Range(1, 3).ToList();
+
             list.InsertBefore(i => i == 2, 42);
 
             list.Count.ShouldBe(4);