More work on #149. Need to be able to unescape paths as well as escape the.

The trick is to unescape paths coming from VSCode as the user may have decided to escape spaces and [ and ].  .NET APIs won't handle those paths.  So we unescape them and cache them in Workspace.cs.  Later, just before we call down to the PowerShell engine to do work that requires the script path, we escape those paths appropriately for PowerShell.

Author: rkeithhill

src/PowerShellEditorServices/Session/PowerShellContext.cs

@@ -12,6 +12,7 @@
 using System.Collections.ObjectModel;
 using System.Linq;
 using System.Text;
+using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -584,16 +585,33 @@ internal void ReleaseRunspaceHandle(RunspaceHandle runspaceHandle)
         /// <returns>The path with [ and ] escaped.</returns>
         internal static string EscapePath(string path, bool escapeSpaces)
         {
-            string escapedPath = path.Replace("[", "`[").Replace("]", "`]");
+            string escapedPath = Regex.Replace(path, @"(?<!`)\[", "`[");
+            escapedPath = Regex.Replace(escapedPath, @"(?<!`)\]", "`]");
 
             if (escapeSpaces)
             {
-                escapedPath = escapedPath.Replace(" ", "` ");
+                escapedPath = Regex.Replace(escapedPath, @"(?<!`) ", "` ");
             }
 
             return escapedPath;
         }
 
+        /// <summary>
+        /// Unescapes any escaped [, ] or space characters. Typically use this before calling a
+        /// .NET API that doesn't understand PowerShell escaped chars.
+        /// </summary>
+        /// <param name="path">The path to unescape.</param>
+        /// <returns>The path with the ` character before [, ] and spaces removed.</returns>
+        internal static string UnescapePath(string path)
+        {
+            if (!path.Contains("`"))
+            {
+                return path;
+            }
+
+            return Regex.Replace(path, @"`(?=[ \[\]])", "");
+        }
+
         #endregion
 
         #region Events

src/PowerShellEditorServices/Workspace/Workspace.cs

@@ -210,6 +210,11 @@ private string ResolveFilePath(string filePath)
                 // Some clients send paths with UNIX-style slashes, replace those if necessary
                 filePath = filePath.Replace('/', '\\');
 
+                // Clients could specify paths with escaped space, [ and ] characters which .NET APIs
+                // will not handle.  These paths will get appropriately escaped just before being passed
+                // into the PowerShell engine.
+                filePath = PowerShellContext.UnescapePath(filePath);
+
                 // Get the absolute file path
                 filePath = Path.GetFullPath(filePath);
             }

test/PowerShellEditorServices.Test/Debugging/DebugServiceTests.cs

@@ -87,9 +87,12 @@ public static IEnumerable<object[]> DebuggerAcceptsScriptArgsTestData
         [MemberData("DebuggerAcceptsScriptArgsTestData")]
         public async Task DebuggerAcceptsScriptArgs(string[] args)
         {
+            // The path is intentionally odd (some escaped chars but not all) because we are testing
+            // the internal path escaping mechanism - it should escape certains chars ([, ] and space) but
+            // it should not escape already escaped chars.
             ScriptFile debugWithParamsFile =
                 this.workspace.GetFile(
-                    @"..\..\..\PowerShellEditorServices.Test.Shared\Debugging\Debug With Params [Test].ps1");
+                    @"..\..\..\PowerShellEditorServices.Test.Shared\Debugging\Debug` With Params `[Test].ps1");
 
             await this.debugService.SetBreakpoints(
                 debugWithParamsFile,