fix: comparison of node names are case insensitive

when the parser in AngleSharp does not know the element type, it will store the name of the node/element in the NodeName property in upper case. This can lead to false negative results. E.g. if one parses "<svg><path></path></svg>" and selects the `<path />` and want to compare that to a "<path>" element parsed alone, the second will be treated as an unknown element, since it was not parsed in the context of a "<svg>" element. The two elements will have the same name though, just in different cases and should thus be equal.

Author: egil

src/AngleSharp.Diffing.Tests/Strategies/NodeStrategies/NodeComparerTest.cs

@@ -1,4 +1,6 @@
-using AngleSharp.Diffing.Core;
+using System;
+
+using AngleSharp.Diffing.Core;
 using AngleSharp.Diffing.Strategies.ElementStrategies;
 
 using Shouldly;
@@ -30,5 +32,16 @@ public void Test002(string controlHtml, string testHtml)
             var comparison = ToComparison(controlHtml, testHtml);
             ElementComparer.Compare(comparison, CompareResult.Unknown).ShouldBe(CompareResult.Different);
         }
+
+        [Theory(DisplayName = "When unknown node is used in comparison, but node name is equal, the result is Same")]
+        [InlineData("<svg><path></path></svg>", "<path/>")]
+        public void HandleUnknownNodeDuringComparison(string controlHtml, string testHtml)
+        {
+            var knownNode = ToNode(controlHtml).FirstChild.ToComparisonSource(0, ComparisonSourceType.Control);
+            var unknownNode = ToNode(testHtml).ToComparisonSource(0, ComparisonSourceType.Test);
+            var comparison = new Comparison(knownNode, unknownNode);
+            
+            ElementComparer.Compare(comparison, CompareResult.Unknown).ShouldBe(CompareResult.Same);
+        }
     }
 }

src/AngleSharp.Diffing/Core/Comparison.cs

@@ -25,7 +25,9 @@ namespace AngleSharp.Diffing.Core
         /// <summary>
         /// Gets whether the control and test nodes are of the same type and has the same name.
         /// </summary>
-        public bool AreNodeTypesEqual => Control.Node.NodeType == Test.Node.NodeType && Control.Node.NodeName == Test.Node.NodeName;
+        public bool AreNodeTypesEqual
+            => Control.Node.NodeType == Test.Node.NodeType
+            && Control.Node.NodeName.Equals(Test.Node.NodeName, StringComparison.OrdinalIgnoreCase);
 
         /// <summary>
         /// Creates a new comparison.