Add a test to prevent regression when XmlUriResolver uses Uri.LocalPath (#28475)

Close #25820 

2 files changed, 78 insertions, 0 deletions

diff --git a/src/System.Private.Xml/tests/Misc/System.Xml.Misc.Tests.csproj b/src/System.Private.Xml/tests/Misc/System.Xml.Misc.Tests.csproj
index 275891669f..102aa3cc79 100644
--- a/src/System.Private.Xml/tests/Misc/System.Xml.Misc.Tests.csproj
+++ b/src/System.Private.Xml/tests/Misc/System.Xml.Misc.Tests.csproj
@@ -10,6 +10,7 @@
   <ItemGroup>
     <Compile Include="RandomizedHashing.cs" />
     <Compile Include="..\..\src\System\Xml\Core\SecureStringHasher.cs" />
+    <Compile Include="XmlUrlResolverTests.cs" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
 </Project>
\ No newline at end of file
diff --git a/src/System.Private.Xml/tests/Misc/XmlUrlResolverTests.cs b/src/System.Private.Xml/tests/Misc/XmlUrlResolverTests.cs
new file mode 100644
index 0000000000..ae7f394cee
--- /dev/null
+++ b/src/System.Private.Xml/tests/Misc/XmlUrlResolverTests.cs
@@ -0,0 +1,77 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.InteropServices;
+using Xunit;
+
+namespace System.Xml.Tests
+{
+    public class XmlUriResolverTests
+    {
+        [Fact]
+        public void Resolving_RelativeBase_Throws()
+        {
+            var resolver = new XmlUrlResolver();
+            Assert.Throws<NotSupportedException>(() => resolver.ResolveUri(
+                new Uri(Environment.CurrentDirectory + Path.DirectorySeparatorChar, UriKind.Relative), "test.xml"));
+        }
+
+        [Theory]
+        [MemberData(nameof(GetBaseUriAndPath))]
+        public void Resolving_LocalPath_Ok(Uri baseUri, string path)
+        {
+            var resolver = new XmlUrlResolver();
+            Uri resolvedUri = resolver.ResolveUri(baseUri, path);
+
+            Assert.Equal(Path.GetFullPath(Path.Combine(Environment.CurrentDirectory, path)), resolvedUri.LocalPath);
+            Assert.True(resolvedUri.LocalPath.EndsWith(path.Replace('/', Path.DirectorySeparatorChar)));
+        }
+
+        [Theory]
+        [MemberData(nameof(XmlFileTargets))]
+        public void Resolving_OnlyWithBaseUri_Ok(string basePath)
+        {
+            var baseUri = new Uri(Path.GetFullPath(basePath));
+            var resolver = new XmlUrlResolver();
+            Uri resolvedUri = resolver.ResolveUri(baseUri, string.Empty);
+
+            Assert.Equal(Path.GetFullPath(basePath), resolvedUri.LocalPath);
+        }
+
+        public static IEnumerable<object[]> GetBaseUriAndPath()
+        {
+            // Base URI as null is the default for internal Xml operation.
+            var baseUris = new List<Uri> { null };
+
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                // The case below does not work on Unix, the '#' ends up treated as a fragment and the path is cut there.
+                var currDirWithDirSeparator = Environment.CurrentDirectory + Path.DirectorySeparatorChar;
+                baseUris.Add(new Uri(currDirWithDirSeparator, UriKind.Absolute));
+                baseUris.Add(new Uri(string.Empty, UriKind.RelativeOrAbsolute));
+            }
+
+            foreach (Uri baseUri in baseUris)
+            {
+                foreach (object[] targetFile in XmlFileTargets)
+                    yield return new object[] { baseUri, targetFile[0] };
+            }
+        }
+
+        public static IEnumerable<object[]> XmlFileTargets => new object[][]
+        {
+            new object[] { "f#/t/\u00eb/test.xml" },
+            new object[] { "/f#/t/\u00eb/t#st.xml" },
+            new object[] { "/f#/\u00e3/\u00eb/t\u00ebst.xml" },
+            new object[] { "u/t/c/test.xml" },
+            new object[] { "u/t/c/t#st.xml" },
+            new object[] { "/u/t/c/t\u00ebst.xml" },
+            new object[] { "test.xml" },
+            new object[] { "t#st.xml" },
+            new object[] { "t\u00ebst.xml" }
+        };
+    }
+}