Visual Studio Web Test: Generating Random unique parameters at runtime

I had a scenario that requires several fields to be unique, and I wanted to have a web test for this scenario. I had the problem of generating these unique parameters to be unique

The first naïve solution I used is to create these unique values using excel and then saving in csv file. Then in my scenario, I set the parameter to a data source from this csv file. But this required me every time I run the scenario to remove the values that are used

Second trial for me, I converted the recorded web test to a coded test, this allowed me to to change the parameters programmatically and also gave me lots of flexibility on the test, on the other hand I lost the usability and flexibility of the web test designer, where I can record more to these test, extract parameters easily, etc..

In the coded test, I was looking for the request that has the parameters that needs to be unique, then I created a function to create a 10 digits random number and returns this as string, like below

public string generateRandomId()
{
    Random rand = new Random();
    string[] random = new string[10];
    for (int i = 0; i < 10; i++)
    {
        random[i] = rand.Next(0, 9).ToString();
    }
    return string.Join("",random);
}

Then at the request parameter setting, I changed from

request8Body.FormPostParameters.Add("Form1:referenceNumberText", "12341212323");

to

request8Body.FormPostParameters.Add("Form1:referenceNumberText", generateRandomId());

Third trial which is the best as believe, I created a web test plugin to set a context parameter at the beginning of the test

First I created a context parameter, by doing right click on the web test, then selecting Add Context Parameter

Then I renamed this parameter to RandomText

Then following the instructions here, http://msdn.microsoft.com/en-US/library/ms243191(v=vs.80).aspx  I created a new project in my solution, and added a new class, called it WebTestPlugin.cs

Added reference to Microsoft.VisualStudio.QualityTools.WebTestFramework and added the following line at the top

using Microsoft.VisualStudio.TestTools.WebTesting;

Then Changed the class name and inherited from WebTestPlugin, the code looked like below

public class webTestPlugin : WebTestPlugin
{
    string randomTxt;
    public override void PreWebTest(object sender, PreWebTestEventArgs e)
    {
        randomTxt = generateRandomId();
        e.WebTest.Context["RandomText"] = randomTxt;
        base.PreWebTest(sender, e);
    }

public string generateRandomId()
{
    Random rand = new Random();
    string[] random = new string[10];
    for (int i = 0; i < 10; i++)
    {
        random[i] = rand.Next(0, 9).ToString();
    }
    return string.Join("",random);
}

}

Then I went to my web test project, added a reference to my plugin project

Then added the plugin to my web test

by doing the above, I had the flexibility of web test designer, and the flexibility of writing my own code in the web test