Add New Node List.IsNullOrEmpty

src/Libraries/CoreNodes/List.cs

@@ -762,14 +762,30 @@ public static IList TakeEveryNthItem(IList list, int n, int offset = 0)
         ///     Determines if the given list is empty.
         /// </summary>
         /// <param name="list">List to be checked if it is empty</param>
-        /// <returns name="bool">True if list is empty, false if it isnt</returns>
+        /// <returns name="bool">True if list is empty, false if it isn't</returns>
         /// <search>test,is,empty,null,count</search>
         [IsVisibleInDynamoLibrary(true)]
         public static bool IsEmpty(IList list)
         {
             return list.Count == 0;
         }
 
+        /// <summary>
+        ///  Determines if the given list is null or empty.
+        /// </summary>
+        /// <param name="list">List to be checked if it is empty or null</param>
+        /// <returns name="bool">True if list is empty or null, false if it isn't</returns>
+        /// <search>test,is,empty,null,count</search>
+        [IsVisibleInDynamoLibrary(true)]
+        public static bool IsNullOrEmpty(IList list)
+        {
+            bool flag1 = list == null;
+            if (flag1) return true;
+            bool flag2 = list.Cast<object>().All(x => x == null);
+            if (flag2) return true;
+            return IsEmpty(list);
+        }
+
         /// <summary>
         ///     Determines if all items in the given list is a boolean and has a true value.
         /// </summary>

src/LibraryViewExtensionMSWebBrowser/web/library/layoutSpecs.json

@@ -63,6 +63,9 @@
                 {
                   "path": "DSCoreNodes.DSCore.List.IsEmpty"
                 },
+                {
+                  "path": "DSCoreNodes.DSCore.List.IsNullOrEmpty"
+                },
                 {
                   "path": "DSCoreNodes.DSCore.List.IndexOf"
                 },

test/Libraries/CoreNodesTests/ListTests.cs

@@ -572,6 +572,17 @@ public static void IsEmptyList()
             Assert.IsTrue(List.IsEmpty(List.Empty));
             Assert.IsFalse(List.IsEmpty(new ArrayList { 1 }));
         }
+        [Test]
+        [Category("UnitTests")]
+        public static void IsNullOrEmptyList()
+        {
+            Assert.IsTrue(List.IsNullOrEmpty(List.Empty));
+            Assert.IsFalse(List.IsNullOrEmpty(new ArrayList { 1 }));
+            Assert.IsTrue(List.IsNullOrEmpty(new ArrayList {  }));
+            Assert.IsTrue(List.IsNullOrEmpty(new ArrayList { null }));
+            Assert.IsTrue(List.IsNullOrEmpty(null));
+            Assert.IsFalse(List.IsNullOrEmpty(new ArrayList{"data",null}));
+        }
 
         [Test]
         [Category("UnitTests")]

test/ViewExtensionLibraryTests/resources/libraryItems.json

@@ -4624,6 +4624,14 @@
       "itemType": "action",
       "keywords": "test, is, empty, null, count"
     },
+    {
+      "fullyQualifiedName": "DSCore.List.IsNullOrEmpty",
+      "iconUrl": null,
+      "contextData": "DSCore.List.IsNullOrEmpty@var[]..[]",
+      "parameters": null,
+      "itemType": "action",
+      "keywords": "test, is, empty, null, count"
+    },
     {
       "fullyQualifiedName": "DSCore.List.AllTrue",
       "iconUrl": "http://localhost/icons/DSCore.List.AllTrue.Small?path=DSCoreNodes.dll",