Add MergeWith dictionary extension

SabreTools.IO.Test/Extensions/DictionaryExtensionsTests.cs

@@ -0,0 +1,86 @@
+using System.Collections.Generic;
+using SabreTools.IO.Extensions;
+using Xunit;
+
+namespace SabreTools.IO.Test.Extensions
+{
+    public class DictionaryExtensionsTests
+    {
+        #region MergeWith
+
+        [Fact]
+        public void MergeWith_EmptySource_EmptyOther_Empty()
+        {
+            Dictionary<string, List<string>> source = [];
+            Dictionary<string, List<string>> other = [];
+
+            source.MergeWith(other);
+            Assert.Empty(source);
+        }
+
+        [Fact]
+        public void MergeWith_EmptySource_EmptyKeyOther_Empty()
+        {
+            Dictionary<string, List<string>> source = [];
+            Dictionary<string, List<string>> other = [];
+            other.Add("key", []);
+
+            source.MergeWith(other);
+            Assert.Empty(source);
+        }
+
+        [Fact]
+        public void MergeWith_EmptySource_FilledOther_Filled()
+        {
+            Dictionary<string, List<string>> source = [];
+            Dictionary<string, List<string>> other = [];
+            other.Add("key", ["value"]);
+
+            source.MergeWith(other);
+            string key = Assert.Single(source.Keys);
+            Assert.Equal("key", key);
+            List<string> actual = source[key];
+            string value = Assert.Single(actual);
+            Assert.Equal("value", value);
+        }
+
+        [Fact]
+        public void MergeWith_FilledSource_EmptyOther_Filled()
+        {
+            Dictionary<string, List<string>> source = [];
+            source.Add("key", ["value"]);
+            Dictionary<string, List<string>> other = [];
+
+            source.MergeWith(other);
+            string key = Assert.Single(source.Keys);
+            Assert.Equal("key", key);
+            List<string> actual = source[key];
+            string value = Assert.Single(actual);
+            Assert.Equal("value", value);
+        }
+
+        [Fact]
+        public void MergeWith_FilledSource_FilledOther_Filled()
+        {
+            Dictionary<string, List<string>> source = [];
+            source.Add("key1", ["value1"]);
+            Dictionary<string, List<string>> other = [];
+            other.Add("key2", ["value2"]);
+
+            source.MergeWith(other);
+            Assert.Equal(2, source.Keys.Count);
+
+            Assert.Contains("key1", source.Keys);
+            List<string> actualKey1 = source["key1"];
+            string value1 = Assert.Single(actualKey1);
+            Assert.Equal("value1", value1);
+
+            Assert.Contains("key2", source.Keys);
+            List<string> actualKey2 = source["key2"];
+            string value2 = Assert.Single(actualKey2);
+            Assert.Equal("value2", value2);
+        }
+
+        #endregion
+    }
+}

SabreTools.IO/Extensions/DictionaryExtensions.cs

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+using System.Collections.Generic;
+
+namespace SabreTools.IO.Extensions
+{
+    public static class DictionaryExtensions
+    {
+        /// <summary>
+        /// Merge a dictionary into an existing one, if possible
+        /// </summary>
+        /// <param name="dict">Source dictionary to add to</param>
+        /// <param name="other">Second dictionary to add from</param>
+        /// <remarks>This only performs a shallow copy</remarks>
+        public static void MergeWith(this Dictionary<string, List<string>> dict, Dictionary<string, List<string>> other)
+        {
+            // Ignore if there are no values to append
+            if (other.Count == 0)
+                return;
+
+            // Loop through and add from the new dictionary
+            foreach (var kvp in other)
+            {
+                // Ignore empty values
+                if (kvp.Value.Count == 0)
+                    continue;
+
+                if (!dict.ContainsKey(kvp.Key))
+                    dict[kvp.Key] = [];
+
+                dict[kvp.Key].AddRange(kvp.Value);
+            }
+        }
+    }
+}