Add parameter for echoing ExecuteScriptString

This change adds a new parameter to PowerShellContext.ExecuteScriptString
which causes the executed script string to be echoed to the host.  This is
useful for "run selection" operations where some selected text is executed
in the REPL.

Author: daviwil

src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

@@ -678,7 +678,8 @@ protected async Task HandleEvaluateRequest(
         {
             var results = 
                 await this.editorSession.PowerShellContext.ExecuteScriptString(
-                    evaluateParams.Expression);
+                    evaluateParams.Expression,
+                    true);
 
             // Return an empty result since the result value is irrelevant
             // for this request in the LanguageServer

src/PowerShellEditorServices/Debugging/DebugService.cs

@@ -238,15 +238,21 @@ public async Task<VariableDetails> EvaluateExpression(string expressionString, i
         {
             var results = 
                 await this.powerShellContext.ExecuteScriptString(
-                    expressionString);
+                    expressionString,
+                    false);
 
             // Since this method should only be getting invoked in the debugger,
             // we can assume that Out-String will be getting used to format results
-            // of command executions into string output.
+            // of command executions into string output.  However, if null is returned
+            // then pass null through so that no output gets displayed.
+            string outputString =
+                results != null ?
+                    string.Join(Environment.NewLine, results) :
+                    null;
 
             return new VariableDetails(
-                expressionString, 
-                string.Join(Environment.NewLine, results));
+                expressionString,
+                outputString);
         }
 
         /// <summary>

src/PowerShellEditorServices/Session/PowerShellContext.cs

@@ -377,8 +377,30 @@ public Task ExecuteCommand(PSCommand psCommand)
         /// </summary>
         /// <param name="scriptString">The script string to execute.</param>
         /// <returns>A Task that can be awaited for the script completion.</returns>
-        public async Task<IEnumerable<object>> ExecuteScriptString(string scriptString)
+        public Task<IEnumerable<object>> ExecuteScriptString(
+            string scriptString)
         {
+            return this.ExecuteScriptString(scriptString, false);
+        }
+
+        /// <summary>
+        /// Executes a script string in the session's runspace.
+        /// </summary>
+        /// <param name="scriptString">The script string to execute.</param>
+        /// <param name="writeInputToHost">If true, causes the script string to be written to the host.</param>
+        /// <returns>A Task that can be awaited for the script completion.</returns>
+        public async Task<IEnumerable<object>> ExecuteScriptString(
+            string scriptString,
+            bool writeInputToHost)
+        {
+            if (writeInputToHost)
+            {
+                ((IConsoleHost)this).WriteOutput(
+                    scriptString + Environment.NewLine,
+                    true,
+                    OutputType.Normal);
+            }
+
             PSCommand psCommand = new PSCommand();
             psCommand.AddScript(scriptString);
 
@@ -547,6 +569,14 @@ private void OnSessionStateChanged(object sender, SessionStateChangedEventArgs e
 
         #region Private Methods
 
+        private void WriteOutput(string outputString, bool includeNewLine)
+        {
+            ((IConsoleHost)this).WriteOutput(
+                outputString,
+                includeNewLine,
+                OutputType.Normal);
+        }
+
         private void WriteExceptionToHost(Exception e)
         {
             const string ExceptionFormat =
@@ -867,6 +897,9 @@ private void OnDebuggerStop(object sender, DebuggerStopEventArgs e)
 
                 if (taskIndex == 0)
                 {
+                    // Write a new output line before continuing
+                    this.WriteOutput("", true);
+
                     e.ResumeAction = this.debuggerStoppedTask.Task.Result;
                     Logger.Write(LogLevel.Verbose, "Received debugger resume action " + e.ResumeAction.ToString());