How to capture a Powershell CmdLet's verbose output when the CmdLet is programmatically Invoked from C#

Question

BACKGROUND

• I am using Powershell 2.0 on Windows 7.
• I am writing a cmdlet in a Powershell module (\"module\" is new to Powershell 2.0).
• To test

Answer 1

• Verbose output is not actually output unless $VerbosePreference is set at least to "Continue."
• Use the PowerShell type to run your cmdlet, and read VerboseRecord instances from the Streams.Verbose propery

Example in powershell script:

ps> $ps = [powershell]::create()
ps> $ps.Commands.AddScript("`$verbosepreference='continue'; write-verbose 42")
ps> $ps.invoke()
ps> $ps.streams.verbose
Message   InvocationInfo                          PipelineIterationInfo
-------   --------------                          ---------------------
42        System.Management.Automation.Invocat... {0, 0}

This should be easy to translate into C#.

Answer 2

1.        string scriptFile = "Test.ps1";
2.        using (PowerShell ps = PowerShell.Create())
3.        {
4.          const string getverbose = "$verbosepreference='continue'"; 
5.          ps.AddScript(string.Format(getverbose));
6.          ps.Invoke();
7.          ps.Commands.Clear();
8.          ps.AddScript(@".\" + scriptFile);
9.          ps.Invoke();
10.         foreach (var v in ps.Streams.Verbose)
11.         {
12.               Console.WriteLine(v.Message);
13.         }
14.       }

Important lines are line 5 and 6. This basically set the $verbosepreference for the session and for upcoming new commands and scripts.