resolves SCM changes ClientUriBuilder

src/AutoRest.CSharp/Common/Output/Expressions/ValueExpressions/IndexerExpression.cs

@@ -1,7 +1,6 @@
 // Copyright(c) Microsoft Corporation.All rights reserved.
 // Licensed under the MIT License.
 
-using System;
 using AutoRest.CSharp.Generation.Writers;
 
 namespace AutoRest.CSharp.Common.Output.Expressions.ValueExpressions

src/AutoRest.CSharp/Common/Output/Models/Types/HelperTypeProviders/System/ClientUriBuilderProvider.cs

@@ -10,7 +10,6 @@
 using AutoRest.CSharp.Common.Output.Expressions.ValueExpressions;
 using AutoRest.CSharp.Common.Output.Models;
 using AutoRest.CSharp.Generation.Types;
-using AutoRest.CSharp.Output.Models.Serialization;
 using AutoRest.CSharp.Output.Models.Shared;
 using static AutoRest.CSharp.Common.Output.Models.Snippets;
 
@@ -32,7 +31,10 @@ private ClientUriBuilderProvider() : base(Configuration.HelperNamespace, null)
         private readonly FieldDeclaration _uriBuilderField = new(FieldModifiers.Private, typeof(UriBuilder), "_uriBuilder");
         private readonly FieldDeclaration _pathBuilderField = new(FieldModifiers.Private, typeof(StringBuilder), "_pathBuilder");
         private readonly FieldDeclaration _queryBuilderField = new(FieldModifiers.Private, typeof(StringBuilder), "_queryBuilder");
-        private readonly FieldDeclaration _pathSeparatorField = new(FieldModifiers.Private | FieldModifiers.Const, typeof(char), "PathSeparator", Literal('/'), SerializationFormat.Default);
+        private readonly FieldDeclaration _pathSeparatorField = new(FieldModifiers.Private | FieldModifiers.Const, typeof(char), "PathSeparator")
+        {
+            InitializationValue = Literal('/')
+        };
 
         protected override IEnumerable<FieldDeclaration> BuildFields()
         {
@@ -147,6 +149,7 @@ private IEnumerable<Method> BuildAppendPathMethods()
             var value = new StringExpression(valueParameter);
             var escape = new BoolExpression(escapeParameter);
             var pathBuilder = new StringBuilderExpression(PathBuilderProperty);
+            var pathSeparator = new CharExpression(_pathSeparatorField);
             MethodBodyStatement body = new MethodBodyStatement[]
             {
                 Argument.AssertNotNullOrWhiteSpace(value),
@@ -156,7 +159,7 @@ private IEnumerable<Method> BuildAppendPathMethods()
                     Assign(value, new InvokeStaticMethodExpression(typeof(Uri), nameof(Uri.EscapeDataString), new[]{ value }))
                 },
                 EmptyLine,
-                new IfStatement(Equal(new IndexerExpression(value, Literal(0)), _pathSeparatorField))
+                new IfStatement(And(Equal(new IndexerExpression(value, Literal(0)), _pathSeparatorField), And(GreaterThan(pathBuilder.Length, Int(0)), Equal(new IndexerExpression(pathBuilder, new BinaryOperatorExpression("-", pathBuilder.Length, Int(1))), _pathSeparatorField))))
                 {
                     Assign(value, value.Substring(Literal(1)))
                 },

test/CadlRanchProjectsNonAzure/authentication/http/custom/src/Generated/Internal/ClientUriBuilder.cs

@@ -42,7 +42,7 @@ public void AppendPath(string value, bool escape)
                 value = Uri.EscapeDataString(value);
             }
 
-            if (value[0] == PathSeparator)
+            if (value[0] == PathSeparator && PathBuilder.Length > 0 && PathBuilder[PathBuilder.Length - 1] == PathSeparator)
             {
                 value = value.Substring(1);
             }

test/UnbrandedProjects.Tests/ClientUriBuilderTests.cs

@@ -0,0 +1,66 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using NUnit.Framework;
+using UnbrandedTypeSpec;
+
+namespace UnbrandedProjects.Tests
+{
+    public class ClientUriBuilderTests
+    {
+        [TestCaseSource(nameof(AppendPathSource))]
+        public void ValidateAppendPath_ToUri(Uri expected, Uri endpoint, params string[] paths)
+        {
+            var uriBuilder = new ClientUriBuilder();
+            uriBuilder.Reset(endpoint);
+            foreach (var path in paths)
+            {
+                uriBuilder.AppendPath(path, false);
+            }
+
+            var uri = uriBuilder.ToUri();
+            Assert.AreEqual(expected, uri);
+        }
+
+        private static readonly object[] AppendPathSource =
+        {
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1"), new Uri("https://api.openai.com/v1"), Array.Empty<string>()
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/"), new Uri("https://api.openai.com/v1/"), Array.Empty<string>()
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething"), new Uri("https://api.openai.com/v1"), new[] { "/doSomething" }
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething"), new Uri("https://api.openai.com/v1/"), new[] { "/doSomething" }
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething/"), new Uri("https://api.openai.com/v1"), new[] { "/doSomething/" }
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething/"), new Uri("https://api.openai.com/v1/"), new[] { "/doSomething/" }
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething/else"), new Uri("https://api.openai.com/v1"), new[] { "/doSomething", "/else" }
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething/else"), new Uri("https://api.openai.com/v1/"), new[] { "/doSomething", "/else" }
+            },
+            new object[]
+            {
+                new Uri("https://api.openai.com/v1/doSomething/else/"), new Uri("https://api.openai.com/v1/"), new[] { "/doSomething/", "/else/" }
+            }
+        };
+    }
+}

test/UnbrandedProjects/Customized-TypeSpec/src/Generated/Internal/ClientUriBuilder.cs

@@ -42,7 +42,7 @@ public void AppendPath(string value, bool escape)
                 value = Uri.EscapeDataString(value);
             }
 
-            if (value[0] == PathSeparator)
+            if (value[0] == PathSeparator && PathBuilder.Length > 0 && PathBuilder[PathBuilder.Length - 1] == PathSeparator)
             {
                 value = value.Substring(1);
             }

test/UnbrandedProjects/NoTest-TypeSpec/src/Generated/Internal/ClientUriBuilder.cs

@@ -42,7 +42,7 @@ public void AppendPath(string value, bool escape)
                 value = Uri.EscapeDataString(value);
             }
 
-            if (value[0] == PathSeparator)
+            if (value[0] == PathSeparator && PathBuilder.Length > 0 && PathBuilder[PathBuilder.Length - 1] == PathSeparator)
             {
                 value = value.Substring(1);
             }

test/UnbrandedProjects/Platform-OpenAI-TypeSpec/src/Generated/Internal/ClientUriBuilder.cs

@@ -42,7 +42,7 @@ public void AppendPath(string value, bool escape)
                 value = Uri.EscapeDataString(value);
             }
 
-            if (value[0] == PathSeparator)
+            if (value[0] == PathSeparator && PathBuilder.Length > 0 && PathBuilder[PathBuilder.Length - 1] == PathSeparator)
             {
                 value = value.Substring(1);
             }

test/UnbrandedProjects/Unbranded-TypeSpec/src/Generated/Internal/ClientUriBuilder.cs

@@ -42,7 +42,7 @@ public void AppendPath(string value, bool escape)
                 value = Uri.EscapeDataString(value);
             }
 
-            if (value[0] == PathSeparator)
+            if (value[0] == PathSeparator && PathBuilder.Length > 0 && PathBuilder[PathBuilder.Length - 1] == PathSeparator)
             {
                 value = value.Substring(1);
             }