Add new constructor to AvaloniaDictionary and include unit tests #17311

src/Avalonia.Base/Collections/AvaloniaDictionary.cs

@@ -34,6 +34,19 @@ public AvaloniaDictionary(int capacity)
             _inner = new Dictionary<TKey, TValue>(capacity);
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AvaloniaDictionary{TKey, TValue}"/> class.
+        /// </summary>
+        public AvaloniaDictionary(Dictionary<TKey, TValue> initialDictionary)
+        {
+            if (initialDictionary == null)
+            {
+                throw new ArgumentNullException(nameof(initialDictionary));
+            }
+            _inner = new Dictionary<TKey, TValue>(initialDictionary);
+        }
+
+
         /// <summary>
         /// Occurs when the collection changes.
         /// </summary>

tests/Avalonia.Base.UnitTests/Collections/AvaloniaDictionaryTests.cs

@@ -156,5 +156,31 @@ public void Clearing_Collection_Should_Raise_PropertyChanged()
 
             Assert.Equal(new[] { "Count", CommonPropertyNames.IndexerName }, tracker.Names);
         }
+
+        [Fact]
+        public void Constructor_Should_Throw_ArgumentNullException_When_Dictionary_Is_Null()
+        {
+            Assert.Throws<ArgumentNullException>(() =>
+            {
+                var target = new AvaloniaDictionary<string, string>(null);
+            });
+        }
+
+        [Fact]
+        public void Constructor_Should_Initialize_With_Provided_Dictionary()
+        {
+            var initialDictionary = new Dictionary<string, string>
+            {
+                { "key1", "value1" },
+                { "key2", "value2" }
+            };
+
+            var target = new AvaloniaDictionary<string, string>(initialDictionary);
+
+            Assert.Equal(2, target.Count);
+            Assert.Equal("value1", target["key1"]);
+            Assert.Equal("value2", target["key2"]);
+        }
+
     }
 }