SLVS-1436 Escape rfc 3986 reserved chars in file names. (#5668)

[SLVS-1436](https://sonarsource.atlassian.net/browse/SLVS-1436)



[SLVS-1436]:
https://sonarsource.atlassian.net/browse/SLVS-1436?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

src/SLCore.UnitTests/Common/Models/FileUriTests.cs

@@ -114,13 +114,67 @@ public void ToString_PercentEncodesBackticks()
         new FileUri(@"C:\filewithbacktick`1").ToString().Should().Be("file:///C:/filewithbacktick%601");
     }
 
+    [TestMethod]
+    [DataRow("[", "%5B")]
+    [DataRow("]", "%5D")]
+    [DataRow("#", "%2523")]
+    [DataRow("@", "%40")]
+    public void ToString_PercentEncodesReservedRfc3986Characters(string reservedChar, string expectedEncoding)
+    {
+        var actualString = @$"C:\filewithRfc3986ReservedChar{reservedChar}.cs";
+        var expectedString = @$"file:///C:/filewithRfc3986ReservedChar{expectedEncoding}.cs";
+
+        new FileUri(actualString).ToString().Should().Be(expectedString);
+    }
+
     [TestMethod]
     public void LocalPath_ReturnsCorrectPath()
     {
         var filePath = @"C:\file\path\with some spaces\and with some backticks`1`2`3";
         new FileUri(filePath).LocalPath.Should().Be(filePath);
     }
 
+    [TestMethod]
+    [DataRow("[", "%5B")]
+    [DataRow("]", "%5D")]
+    [DataRow("#", "%2523")]
+    [DataRow("@", "%40")]
+    [DataRow(" ", "%20")]
+    [DataRow("`", "%60")]
+    public void LocalPath_UnescapesEncodesCharacters(string reservedChar, string expectedEncoding)
+    {
+        var expectedFilePath = @$"C:\filewithRfc3986ReservedChar{reservedChar}.cs";
+        var encodedFilePath = @$"file:///C:/filewithRfc3986ReservedChar{expectedEncoding}.cs";
+
+        new FileUri(encodedFilePath).LocalPath.Should().Be(expectedFilePath);
+    }
+
+    [TestMethod]
+    [DataRow("[")]
+    [DataRow("]")]
+    [DataRow("@")]
+    [DataRow(" ")]
+    [DataRow("`")]
+    public void LocalPath_PathDoesNotHaveEncodedChars_ReturnsCorrectLocalPath(string reservedChar)
+    {
+        var notEncodedFilePath = @$"file:///C:/filewithRfc3986ReservedChar{reservedChar}.cs";
+        var expectedFilePath = @$"C:\filewithRfc3986ReservedChar{reservedChar}.cs";
+
+        new FileUri(notEncodedFilePath).LocalPath.Should().Be(expectedFilePath);
+    }
+
+    /// <summary>
+    ///  The # character as the beginning of a fragment, so <see cref="Uri.LocalPath"/> will return the path without the fragment.
+    /// </summary>
+    [TestMethod]
+    public void LocalPath_PathWithHashCharacter_ReturnsLocalPathWithoutHash()
+    {
+        var notEncodedFilePath = @$"file:///C:/filewithRfc3986ReservedChar#.cs";
+        var expectedFilePath = @$"C:\filewithRfc3986ReservedChar";
+
+        new FileUri(notEncodedFilePath).LocalPath.Should().Be(expectedFilePath);
+    }
+
     [TestMethod]
     public void SerializeDeserializeToEqualObject()
     {
@@ -152,4 +206,15 @@ public void Deserialize_ProducesCorrectUri()
         fileUri.ToString().Should().Be("file:///C:/file%20with%20%204%20spaces%20and%20a%20back%60tick");
         fileUri.LocalPath.Should().Be(@"C:\file with  4 spaces and a back`tick");
     }
+
+    [TestMethod]
+    public void Deserialize_ReservedRfc3986Characters_ProducesCorrectUri()
+    {
+        var serialized = @"""file:///C:/file%5B%5Dand%2523and%40""";
+
+        var fileUri = JsonConvert.DeserializeObject<FileUri>(serialized);
+
+        fileUri.ToString().Should().Be("file:///C:/file%5B%5Dand%2523and%40");
+        fileUri.LocalPath.Should().Be(@"C:\file[]and#and@");
+    }
 }

src/SLCore/Common/Models/FileUri.cs

@@ -20,6 +20,7 @@
 
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
+using System.Text;
 using SonarLint.VisualStudio.SLCore.Protocol;
 
 namespace SonarLint.VisualStudio.SLCore.Common.Models;
@@ -28,15 +29,38 @@ namespace SonarLint.VisualStudio.SLCore.Common.Models;
 public sealed class FileUri
 {
     private readonly Uri uri;
+    private static readonly char[] Rfc3986ReservedCharsToEncode = ['#', '[', ']', '@'];
 
     public FileUri(string uriString)
     {
-        uri = new Uri(uriString);
+        var unescapedUri = Uri.UnescapeDataString(uriString);
+        uri = new Uri(unescapedUri);
     }
 
     public string LocalPath => uri.LocalPath;
 
-    public override string ToString() => Uri.EscapeUriString(uri.ToString());
+    public override string ToString()
+    {
+        var escapedUri = Uri.EscapeUriString(uri.ToString());
+
+        return EscapeRfc3986ReservedCharacters(escapedUri);
+    }
+
+    /// <summary>
+    /// The backend (SlCore) uses java, in which the Uri follows the RFC 3986 protocol.
+    /// The <see cref="Uri.EscapeUriString"/> does not escape the reserved characters, that's why they are escaped here.
+    /// See https://learn.microsoft.com/en-us/dotnet/api/system.uri.escapeuristring?view=netframework-4.7.2
+    /// </summary>
+    /// <param name="stringToEscape"></param>
+    /// <returns></returns>
+    private static string EscapeRfc3986ReservedCharacters(string stringToEscape)
+    {
+        var stringBuilderToEscape = new StringBuilder(stringToEscape);
+
+        return Rfc3986ReservedCharsToEncode.Aggregate(stringBuilderToEscape,
+                (current, charToEscape) => current.Replace(charToEscape.ToString(), Uri.HexEscape(charToEscape)))
+                .ToString();
+    }
 
     [ExcludeFromCodeCoverage]
     public override bool Equals(object obj)