Add AddChildrenFrom method to CommandSet

SabreTools.CommandLine.Test/CommandSetTests.cs

@@ -13,9 +13,16 @@ namespace SabreTools.CommandLine.Test
             var input1 = new FlagInput("input1", "--input1", "input1");
             var input2 = new FlagInput("input2", "--input2", "input2");
 
+            var feature1 = new MockFeature("feature1", "feature1", "feature1");
+            var inputA = new FlagInput("inputA", "--inputA", "inputA");
+            var inputB = new FlagInput("inputB", "--inputB", "inputB");
+            feature1.Add(inputA);
+            feature1.Add(inputB);
+
             var featureSet = new CommandSet();
             featureSet.Add(input1);
             featureSet.Add(input2);
+            featureSet.AddChildrenFrom(feature1);
 
             var actualInput1 = featureSet["input1"];
             Assert.NotNull(actualInput1);
@@ -27,6 +34,14 @@ namespace SabreTools.CommandLine.Test
 
             var actualInput3 = featureSet["input3"];
             Assert.Null(actualInput3);
+
+            var actualInputA = featureSet["inputA"];
+            Assert.NotNull(actualInputA);
+            Assert.Equal("inputA", actualInputA.Name);
+
+            var actualinputB = featureSet["inputB"];
+            Assert.NotNull(actualinputB);
+            Assert.Equal("inputB", actualinputB.Name);
         }
 
         [Fact]

SabreTools.CommandLine/CommandSet.cs

@@ -120,6 +120,29 @@ namespace SabreTools.CommandLine
         public void Add(UserInput input)
             => _inputs.Add(input.Name, input);
 
+        /// <summary>
+        /// Add all children from an input to the set
+        /// </summary>
+        /// <param name="input">UserInput object to retrieve children from</param>
+        /// <remarks>
+        /// This should only be used in situations where an input is defined
+        /// but not used within the context of the command set directly.
+        /// 
+        /// This is helpful for when there are applications with default functionality
+        /// that need to be able to expose both defined features as well as
+        /// the default functionality in help text.
+        /// 
+        /// If there is any overlap between existing names and the names from
+        /// any of the children, this operation will overwrite them.
+        /// </reamrks>
+        public void AddChildrenFrom(UserInput input)
+        {
+            foreach (var kvp in input.Children)
+            {
+                _inputs.Add(kvp.Key, kvp.Value);
+            }
+        }
+
         #endregion
 
         #region Children

SabreTools.CommandLine/Inputs/UserInput.cs

@@ -41,7 +41,7 @@ namespace SabreTools.CommandLine.Inputs
         /// <summary>
         /// Set of children associated with this input
         /// </summary>
-        protected readonly Dictionary<string, UserInput> Children = [];
+        internal protected readonly Dictionary<string, UserInput> Children = [];
 
         #endregion