Fixed return type

Author: sakno

src/DotNext.Tests/IO/FileUriTests.cs

@@ -38,7 +38,7 @@ public static TheoryData<string, string> GetPaths()
     [MemberData(nameof(GetPaths))]
     public static void EncodeAsUri(string fileName, string expected)
     {
-        var uri = FileUri.Encode(fileName);
+        var uri = new Uri(FileUri.Encode(fileName), UriKind.Absolute);
         True(uri.IsFile);
         Equal(expected, uri.LocalPath);
     }

src/DotNext/IO/FileUri.cs

@@ -30,19 +30,20 @@ public static class FileUri
     /// </summary>
     /// <param name="fileName">The fully-qualified file name.</param>
     /// <param name="settings">The encoding settings.</param>
-    /// <returns><paramref name="fileName"/> as <see cref="Uri"/>.</returns>
+    /// <returns><paramref name="fileName"/> as URI. The return value can be passed to <see cref="Uri(string)"/> constructor.</returns>
     /// <exception cref="ArgumentException"><paramref name="fileName"/> is not fully-qualified.</exception>
-    public static Uri Encode(ReadOnlySpan<char> fileName, TextEncoderSettings? settings = null)
+    public static string Encode(ReadOnlySpan<char> fileName, TextEncoderSettings? settings = null)
     {
         ThrowIfPartiallyQualified(fileName);
         var encoder = settings is null ? UrlEncoder.Default : UrlEncoder.Create(settings);
         var maxLength = GetMaxEncodedLengthCore(fileName, encoder);
         using var buffer = (uint)maxLength <= (uint)SpanOwner<char>.StackallocThreshold
             ? stackalloc char[maxLength]
             : new SpanOwner<char>(maxLength);
-
-        TryEncodeCore(fileName, encoder, buffer.Span, out var writtenCount);
-        return new(buffer.Span.Slice(0, writtenCount).ToString(), UriKind.Absolute);
+        
+        return TryEncodeCore(fileName, encoder, buffer.Span, out var writtenCount)
+            ? buffer.Span.Slice(0, writtenCount).ToString()
+            : string.Empty;
     }
 
     /// <summary>