Fix HtmlDifferenceEngineTest

Author: grishat

src/AngleSharp.Diffing.Tests/Core/HtmlDifferenceEngineTest.cs

@@ -357,13 +357,15 @@ public void Test2()
             results.ShouldBeEmpty();
         }
 
-        [Fact(DisplayName = "When comparer returns SkipChildren from an element comparison, child nodes are not compared")]
-        public void Test3()
+        [Theory(DisplayName = "When comparer returns SkipChildren flag from an element comparison, child nodes are not compared")]
+        [InlineData(CompareResult.Same | CompareResult.SkipChildren)]
+        [InlineData(CompareResult.Skip | CompareResult.SkipChildren)]
+        public void Test3(CompareResult compareResult)
         {
             var sut = CreateHtmlDiffer(
                 nodeMatcher: OneToOneNodeListMatcher,
                 nodeFilter: NoneNodeFilter,
-                nodeComparer: c => c.Control.Node.NodeName == "P" ? CompareResult.Same | CompareResult.SkipChildren : throw new Exception("NODE COMPARER SHOULD NOT BE CALLED ON CHILD NODES"),
+                nodeComparer: c => c.Control.Node.NodeName == "P" ? compareResult : throw new Exception("NODE COMPARER SHOULD NOT BE CALLED ON CHILD NODES"),
                 attrMatcher: AttributeNameMatcher,
                 attrFilter: NoneAttrFilter,
                 attrComparer: SameResultAttrComparer
@@ -374,13 +376,15 @@ public void Test3()
             results.ShouldBeEmpty();
         }
 
-        [Fact(DisplayName = "When comparer returns SkipAttributes from an element comparison, attributes are not compared")]
-        public void Test4()
+        [Theory(DisplayName = "When comparer returns SkipAttributes flag from an element comparison, attributes are not compared")]
+        [InlineData(CompareResult.Same | CompareResult.SkipAttributes)]
+        [InlineData(CompareResult.Skip | CompareResult.SkipAttributes)]
+        public void Test4(CompareResult compareResult)
         {
             var sut = CreateHtmlDiffer(
                 nodeMatcher: OneToOneNodeListMatcher,
                 nodeFilter: NoneNodeFilter,
-                nodeComparer: c => CompareResult.Same | CompareResult.SkipAttributes,
+                nodeComparer: c => compareResult,
                 attrMatcher: AttributeNameMatcher,
                 attrFilter: NoneAttrFilter,
                 attrComparer: SameResultAttrComparer

src/AngleSharp.Diffing/Core/HtmlDifferenceEngine.cs

@@ -111,7 +111,7 @@ private IEnumerable<IDiff> CompareElement(in Comparison comparison)
                 result.Add(new NodeDiff(comparison));
             }
 
-            if (compareRes != CompareResult.Skip)
+            if (!compareRes.HasFlag(CompareResult.Skip))
             {
                 if (!compareRes.HasFlag(CompareResult.SkipAttributes))
                     result.AddRange(CompareElementAttributes(comparison));