Make setting null create a null object instead of removing

Author: xPaw

ValveKeyValue/ValveKeyValue.Test/ConversionCoverageTestCase.cs

@@ -240,7 +240,7 @@ public void DictBackedCollectionSetChildViaIndexer()
         }
 
         [Test]
-        public void DictBackedCollectionSetNullRemovesKey()
+        public void DictBackedCollectionSetNullStoresNullValue()
         {
             var kv3Text = "<!-- kv3 encoding:text:version{e21c7f3c-8a33-41c5-9977-a76d3a32aa0d} format:generic:version{7412167c-06e9-4698-aff2-e63eb59037e7} -->\n{\n\tkey1 = \"value1\"\n\tkey2 = 42\n}";
             using var stream = new MemoryStream(Encoding.UTF8.GetBytes(kv3Text));
@@ -250,8 +250,8 @@ public void DictBackedCollectionSetNullRemovesKey()
 
             data["key1"] = null;
 
-            Assert.That(data.ContainsKey("key1"), Is.False);
-            Assert.That(data.Count, Is.EqualTo(1));
+            Assert.That(data.Count, Is.EqualTo(2));
+            Assert.That(data["key1"].IsNull, Is.True);
             Assert.That((int)data["key2"], Is.EqualTo(42));
         }
 

ValveKeyValue/ValveKeyValue.Test/EdgeCaseTestCase.cs

@@ -80,29 +80,30 @@ public void IndexerSetRemovesDuplicatesAndKeepsFirstPosition()
         #region Indexer set with null removes child
 
         [Test]
-        public void IndexerSetNullRemovesChildFromListCollection()
+        public void IndexerSetNullStoresNullValue()
         {
             var obj = KVObject.ListCollection();
             obj.Add("a", "1");
             obj.Add("b", "2");
 
             obj["a"] = null;
 
-            Assert.That(obj.ContainsKey("a"), Is.False);
-            Assert.That(obj.Count, Is.EqualTo(1));
+            Assert.That(obj.Count, Is.EqualTo(2));
+            Assert.That(obj["a"].IsNull, Is.True);
             Assert.That((string)obj["b"], Is.EqualTo("2"));
         }
 
         [Test]
-        public void IndexerSetNullOnMissingKeyDoesNotThrow()
+        public void IndexerSetNullOnMissingKeyStoresNullValue()
         {
             var obj = KVObject.ListCollection();
             obj.Add("a", "1");
 
             obj["nonexistent"] = null;
 
-            Assert.That(obj.Count, Is.EqualTo(1));
+            Assert.That(obj.Count, Is.EqualTo(2));
             Assert.That((string)obj["a"], Is.EqualTo("1"));
+            Assert.That(obj["nonexistent"].IsNull, Is.True);
         }
 
         #endregion
@@ -594,15 +595,16 @@ public void RemoveDuplicateKeysFromListCollectionRemovesAll()
         #region SetChild null on dict-backed missing key is no-op
 
         [Test]
-        public void IndexerSetNullOnMissingKeyInDictCollectionIsNoOp()
+        public void IndexerSetNullOnMissingKeyInDictCollectionStoresNullValue()
         {
             var obj = KVObject.Collection();
             obj.Add("a", 1);
 
             obj["nonexistent"] = null;
 
-            Assert.That(obj.Count, Is.EqualTo(1));
+            Assert.That(obj.Count, Is.EqualTo(2));
             Assert.That((int)obj["a"], Is.EqualTo(1));
+            Assert.That(obj["nonexistent"].IsNull, Is.True);
         }
 
         #endregion

ValveKeyValue/ValveKeyValue/KVObject.cs

@@ -512,42 +512,29 @@ internal List<KeyValuePair<string, KVObject>> GetCollectionList()
 
         private void SetChild(string key, KVObject value)
         {
+            value ??= Null();
+
             switch (_ref)
             {
                 case Dictionary<string, KVObject> dict:
-                    if (value == null)
-                    {
-                        dict.Remove(key);
-                    }
-                    else
-                    {
-                        dict[key] = value;
-                    }
-
+                    dict[key] = value;
                     break;
                 case List<KeyValuePair<string, KVObject>> list when ValueType == KVValueType.Collection:
                     var firstIndex = list.FindIndex(c => c.Key == key);
                     if (firstIndex >= 0)
                     {
-                        if (value != null)
-                        {
-                            list[firstIndex] = new KeyValuePair<string, KVObject>(key, value);
+                        list[firstIndex] = new KeyValuePair<string, KVObject>(key, value);
 
-                            // Remove any remaining duplicates after the replaced entry
-                            for (var i = list.Count - 1; i > firstIndex; i--)
+                        // Remove any remaining duplicates after the replaced entry
+                        for (var i = list.Count - 1; i > firstIndex; i--)
+                        {
+                            if (list[i].Key == key)
                             {
-                                if (list[i].Key == key)
-                                {
-                                    list.RemoveAt(i);
-                                }
+                                list.RemoveAt(i);
                             }
                         }
-                        else
-                        {
-                            list.RemoveAll(c => c.Key == key);
-                        }
                     }
-                    else if (value != null)
+                    else
                     {
                         list.Add(new KeyValuePair<string, KVObject>(key, value));
                     }