fix: tree node has the wrong structure because of trailing slashes

src/Microsoft.OpenApi/Services/OpenApiUrlTreeNode.cs

@@ -59,7 +59,7 @@
         {
             Utils.CheckArgumentNullOrEmpty(label);
 
-            return PathItems is not null && PathItems.TryGetValue(label, out var item) && item.Operations is not null && item.Operations.Any();
+            return PathItems is not null && PathItems.TryGetValue(label, out var item) && item.Operations is { Count : > 0 };
         }
 
         /// <summary>
@@ -93,7 +93,7 @@
 
             var root = Create();
 
             var paths = doc?.Paths;
             if (paths != null)
             {
                 foreach (var path in paths)
@@ -151,13 +151,6 @@
             }
 
             var segments = path.Split('/');
-            if (path.EndsWith("/", StringComparison.OrdinalIgnoreCase))
-            {
-                // Remove the last element, which is empty, and append the trailing slash to the new last element
-                // This is to support URLs with trailing slashes
-                Array.Resize(ref segments, segments.Length - 1);
-                segments[segments.Length - 1] += @"\";
-            }
 
             return Attach(segments: segments,
                           pathItem: pathItem,
@@ -179,7 +172,8 @@
                                           string currentPath)
         {
             var segment = segments.FirstOrDefault();
-            if (string.IsNullOrEmpty(segment))
+            // empty segment is significant
+            if (segment is null)
             {
                 if (PathItems.ContainsKey(label))
                 {
@@ -190,6 +184,13 @@
                 PathItems.Add(label, pathItem);
                 return this;
             }
+            // special casing for '/' (root node)
+            if (segment.Length == 0 && currentPath.Length == 0)
+            {
+                Path = currentPath;
+                PathItems.Add(label, pathItem);
+                return this;
+            }
 
             // If the child segment has already been defined, then insert into it
             if (Children.TryGetValue(segment, out var child))

test/Microsoft.OpenApi.Tests/Services/OpenApiUrlTreeNodeTests.cs

@@ -230,6 +230,66 @@ public void CreatePathsWithMultipleSegmentsWorks()
             Assert.Equal("coupes", rootNode.Children["cars"].Children["coupes"].Segment);
         }
 
+        [Fact]
+        public void CreatePathsWithTrailingSlashWorks()
+        {
+            var doc = new OpenApiDocument
+            {
+                Paths = new()
+                {
+                    ["/"] = new OpenApiPathItem(),
+                    ["/cars"] = new OpenApiPathItem(),
+                    ["/cars/"] = new OpenApiPathItem(),
+                    ["/cars/coupes"] = new OpenApiPathItem()
+                }
+            };
+
+            var label = "assets";
+            var rootNode = OpenApiUrlTreeNode.Create(doc, label);
+
+            Assert.NotNull(rootNode);
+            Assert.Single(rootNode.Children);
+            var carsNode = rootNode.Children["cars"];
+            Assert.Equal("cars", carsNode.Segment);
+            Assert.Equal(2, carsNode.Children.Count);
+            var emptyNode = carsNode.Children[""];
+            Assert.Empty(emptyNode.Segment);
+            Assert.Empty(emptyNode.Children);
+            var coupesNode = carsNode.Children["coupes"];
+            Assert.Equal("coupes", coupesNode.Segment);
+            Assert.Empty(coupesNode.Children);
+        }
+
+        [Fact]
+        public void CreatePathsWithTrailingSlashWorksInverted()
+        {
+            var doc = new OpenApiDocument
+            {
+                Paths = new()
+                {
+                    ["/"] = new OpenApiPathItem(),
+                    ["/cars/"] = new OpenApiPathItem(),
+                    ["/cars"] = new OpenApiPathItem(), // only difference from previous test, tests that node mapping is not order specific
+                    ["/cars/coupes"] = new OpenApiPathItem()
+                }
+            };
+
+            var label = "assets";
+            var rootNode = OpenApiUrlTreeNode.Create(doc, label);
+
+            Assert.NotNull(rootNode);
+            Assert.Single(rootNode.Children);
+            var carsNode = rootNode.Children["cars"];
+            Assert.Equal("cars", carsNode.Segment);
+            Assert.Equal(2, carsNode.Children.Count);
+            var emptyNode = carsNode.Children[""];
+            Assert.Empty(emptyNode.Segment);
+            Assert.Empty(emptyNode.Children);
+            var coupesNode = carsNode.Children["coupes"];
+            Assert.Equal("coupes", coupesNode.Segment);
+            Assert.Empty(coupesNode.Children);
+        }
+
         [Fact]
         public void HasOperationsWorks()
         {
@@ -468,16 +528,16 @@ public async Task VerifyDiagramFromSampleOpenAPIAsync()
             await Verifier.Verify(diagram);
         }
 
-        public static TheoryData<string, string[], string, string> SupportsTrailingSlashesInPathData => new TheoryData<string, string[], string, string>
+        public static TheoryData<string, string[], string> SupportsTrailingSlashesInPathData => new TheoryData<string, string[], string>
         {
             // Path, children up to second to leaf, last expected leaf node name, expected leaf node path
-            { "/cars/{car-id}/build/", ["cars", "{car-id}"], @"build\", @"\cars\{car-id}\build\" },
-            { "/cars/", [], @"cars\", @"\cars\" },
+            { "/cars/{car-id}/build/", ["cars", "{car-id}", "build"], @"\cars\{car-id}\build\" },
+            { "/cars/", ["cars"], @"\cars\" },
         };
 
         [Theory]
         [MemberData(nameof(SupportsTrailingSlashesInPathData))]
-        public void SupportsTrailingSlashesInPath(string path, string[] childrenBeforeLastNode, string expectedLeafNodeName, string expectedLeafNodePath)
+        public void SupportsTrailingSlashesInPath(string path, string[] childrenBeforeLastNode, string expectedLeafNodePath)
         {
             var openApiDocument = new OpenApiDocument
             {
@@ -496,7 +556,7 @@ public void SupportsTrailingSlashesInPath(string path, string[] childrenBeforeLa
                 secondToLeafNode = secondToLeafNode.Children[childName];
             }
 
-            Assert.True(secondToLeafNode.Children.TryGetValue(expectedLeafNodeName, out var leafNode));
+            Assert.True(secondToLeafNode.Children.TryGetValue(string.Empty, out var leafNode));
             Assert.Equal(expectedLeafNodePath, leafNode.Path);
             Assert.Empty(leafNode.Children);
         }