Date and time plugin for Visual Studio Web Test

A Visual Studio web performance test required the current date and time to be written to a context parameter for inserting into a request. Writing the current date and time to a string is straightforward and it is simple to write a string into a content parameter within the web test plugin.

using Microsoft.VisualStudio.TestTools.WebTesting;

namespace Plugins
{
    [System.ComponentModel.DisplayName(
        "Save current date time to context parameter")]
    [System.ComponentModel.Description(
        "Saves date time of call to a context parameter")]
    public class DateTimeToContext : WebTestRequestPlugin
    {
        [System.ComponentModel.DisplayName("Parameter name")]
        [System.ComponentModel.Description("Name of context parameter.")]
        public string ParameterName { get; set; }

        [System.ComponentModel.DisplayName("Date-time format")]
        [System.ComponentModel.DefaultValue("yyyy-MM-dd HH:mm:ss.fff")]
        public string DateTimeFormat { get; set; }

        public override void PreRequest(object sender, PreRequestEventArgs e)
        {
            string now 
                = string.IsNullOrWhiteSpace(DateTimeFormat) 
                ? System.DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff")
                : System.DateTime.Now.ToString(DateTimeFormat);

            e.WebTest.AddCommentToResult(string.Format(
                "Setting context parameter '{0}' to '{1}'", ParameterName, now));
            e.WebTest.Context[ParameterName] = now;
        }
    }
} 

I like to add calls of e.WebTest.AddCommentToResult(...) at significant places in plugins, particularly when developing a plugin or a web test. In this case it simply reports the values that are set into the web test log.