Change debug launch handler to treat null/empty cwd to not change dir

Fix for PowerShell/vscode-powershell#1330

Removes deprecated "Program" field from LaunchRequest class.
Simplifies working dir logic in HandleLaunchRequest.  Basically if the
launch request happens in the regular integrated console, a null/empty
cwd means "do not change the working dir".  If the request is using the
temp integrated console, there is no "existing" workng dir, so we use
the original logic to set the working dir.

Author: rkeithhill

src/PowerShellEditorServices.Protocol/DebugAdapter/LaunchRequest.cs

@@ -18,12 +18,6 @@ public static readonly
 
     public class LaunchRequestArguments
     {
-        /// <summary>
-        /// Gets or sets the absolute path to the program to debug.
-        /// </summary>
-        [Obsolete("This property has been deprecated in favor of the Script property.")]
-        public string Program { get; set; }
-
         /// <summary>
         /// Gets or sets the absolute path to the script to debug.
         /// </summary>

src/PowerShellEditorServices.Protocol/Server/DebugAdapter.cs

@@ -255,22 +255,9 @@ protected async Task HandleLaunchRequest(
             this.RegisterEventHandlers();
 
             // Set the working directory for the PowerShell runspace to the cwd passed in via launch.json.
-            // In case that is null, use the the folder of the script to be executed.  If the resulting
-            // working dir path is a file path then extract the directory and use that.
-            string workingDir =
-                launchParams.Cwd ??
-                launchParams.Script ??
-#pragma warning disable 618
-                launchParams.Program;
-#pragma warning restore 618
-
-            // When debugging an "untitled" (unsaved) file - the working dir can't be derived
-            // from the Script path.  OTOH, if the launch params specifies a Cwd, use it.
-            if (ScriptFile.IsUntitledPath(workingDir) && string.IsNullOrEmpty(launchParams.Cwd))
-            {
-                workingDir = null;
-            }
+            string workingDir = launchParams.Cwd;
 
+            // Assuming we have a specified working dir, unescape the path and verify it.
             if (!string.IsNullOrEmpty(workingDir))
             {
                 workingDir = PowerShellContext.UnescapePath(workingDir);
@@ -289,18 +276,28 @@ protected async Task HandleLaunchRequest(
                 }
             }
 
-            if (string.IsNullOrEmpty(workingDir))
+            // A null or empty string value for CWD is an indicator to NOT change the working directory
+            // but only if we are debugging in the integrated console where there is an existing cwd.
+            // However, if we are running in a temporary integrated console, there is no pre-existing
+            // cwd, so fall through to the "else if: where we set a working directory.
+            if (string.IsNullOrEmpty(workingDir) && !launchParams.CreateTemporaryIntegratedConsole)
             {
+                Logger.Write(LogLevel.Verbose, "Launch config requested working dir not be changed/set");
+            }
+            else if (this.editorSession.PowerShellContext.CurrentRunspace.Location == RunspaceLocation.Local &&
+                     !this.editorSession.DebugService.IsDebuggerStopped)
+            {
+                // If we have no working dir by this point, pick some reasonable default.
+                if (string.IsNullOrEmpty(workingDir))
+                {
 #if CoreCLR
-                workingDir = AppContext.BaseDirectory;
+                    //TODO: RKH 2018-06-26 .NET standard 2.0 has added Environment.CurrentDirectory - let's use it.
+                    workingDir = AppContext.BaseDirectory;
 #else
-                workingDir = Environment.CurrentDirectory;
+                    workingDir = Environment.CurrentDirectory;
 #endif
-            }
+                }
 
-            if (this.editorSession.PowerShellContext.CurrentRunspace.Location == RunspaceLocation.Local &&
-                !this.editorSession.DebugService.IsDebuggerStopped)
-            {
                 await editorSession.PowerShellContext.SetWorkingDirectory(workingDir, isPathAlreadyEscaped: false);
                 Logger.Write(LogLevel.Verbose, "Working dir set to: " + workingDir);
             }
@@ -316,7 +313,7 @@ protected async Task HandleLaunchRequest(
             // Store the launch parameters so that they can be used later
             this.noDebug = launchParams.NoDebug;
 #pragma warning disable 618
-            this.scriptToLaunch = launchParams.Script ?? launchParams.Program;
+            this.scriptToLaunch = launchParams.Script;
 #pragma warning restore 618
             this.arguments = arguments;
             this.IsUsingTempIntegratedConsole = launchParams.CreateTemporaryIntegratedConsole;