PrefixedFileProvider: Forward all paths unchanged when prefix is "/"

src/Ramstack.FileProviders/PrefixedFileProvider.cs

@@ -98,6 +98,9 @@ public void Dispose() =>
     {
         Debug.Assert(path == FilePath.Normalize(path));
 
+        if (prefix == "/")
+            return path;
+
         if (path == prefix)
             return "/";
 

tests/Ramstack.FileProviders.Tests/PrefixedFileProviderTests.cs

@@ -12,6 +12,11 @@ public sealed class PrefixedFileProviderTests : AbstractFileProviderTests
             .GetMethod("ResolveGlobFilter", BindingFlags.Static | BindingFlags.NonPublic)!
             .CreateDelegate<Func<string, string, string?>>();
 
+    private static readonly Func<string, string, string?> s_resolvePath =
+        typeof(PrefixedFileProvider)
+            .GetMethod("ResolvePath", BindingFlags.Static | BindingFlags.NonPublic)!
+            .CreateDelegate<Func<string, string, string?>>();
+
     private readonly TempFileStorage _storage = new TempFileStorage();
 
     protected override IFileProvider GetFileProvider() =>
@@ -37,4 +42,52 @@ protected override DirectoryInfo GetDirectoryInfo() =>
     [TestCase("/modules/profile/assets", "/*.js", ExpectedResult = null)]
     public string? ResolveGlobFilter(string prefix, string filter) =>
         s_resolveGlobFilter(prefix, filter);
+
+    [TestCase("/", "/",            ExpectedResult = "/")]
+    [TestCase("/", "/foo",         ExpectedResult = "/foo")]
+    [TestCase("/", "/a/b/c",       ExpectedResult = "/a/b/c")]
+
+    [TestCase("/a/b", "/a/b",      ExpectedResult = "/")]
+
+    [TestCase("/a/b", "/a/b/c",    ExpectedResult = "/c")]
+    [TestCase("/a/b", "/a/b/c/d",  ExpectedResult = "/c/d")]
+
+    [TestCase("/a/b", "/a/bc",     ExpectedResult = null)]
+
+    [TestCase("/a/b", "/a/c",      ExpectedResult = null)]
+    [TestCase("/a/b", "/a",        ExpectedResult = null)]
+    public string? ResolvePath(string prefix, string path) =>
+        s_resolvePath(prefix, path);
+
+    [Test]
+    public void GetFileInfo_RootPrefix_DelegatesToInnerProvider()
+    {
+        using var provider = new PrefixedFileProvider("/",
+            new PhysicalFileProvider(_storage.Root, ExclusionFilters.None));
+
+        var file = provider.GetFileInfo("/project/README.md");
+        Assert.That(file.Exists, Is.True);
+        Assert.That(file.IsDirectory, Is.False);
+    }
+
+    [Test]
+    public void GetDirectoryContents_RootPrefix_DelegatesToInnerProvider()
+    {
+        using var provider = new PrefixedFileProvider("/",
+            new PhysicalFileProvider(_storage.Root, ExclusionFilters.None));
+
+        var contents = provider.GetDirectoryContents("/project/docs");
+        Assert.That(contents.Exists, Is.True);
+        Assert.That(contents.Any(), Is.True);
+    }
+
+    [Test]
+    public void GetFileInfo_RootPrefix_MissingFile_ReturnsNotFound()
+    {
+        using var provider = new PrefixedFileProvider("/",
+            new PhysicalFileProvider(_storage.Root, ExclusionFilters.None));
+
+        var file = provider.GetFileInfo("/project/nonexistent.txt");
+        Assert.That(file.Exists, Is.False);
+    }
 }