visual studio web test error handling - visual-studio

Question

I'm using Visual Studio Ultimate 2013 and have a load test that uses a web test with a number of request and web test plugins.
In my PostRequest plugin, I'm checking the http status code of the response and am flagging an error in a WebTest.Context parameter, when a hhtp code of over 400 is returned. What I want to do is pick this up in the PostTransaction WebTest plugin and update a database table. The problem is, that the test aborts when the framework detects the error and the PostTransaction plugin isn't called.
I've added a PostWebTest plugin, that I thought would be called when the test iteration aborted, but it's never hitting this when a request fails. It does hit it if the test is successful. What am I missing?
public override void PostRequest(object sender, PostRequestEventArgs e)
{
...
statusCode = e.Response.StatusCode.GetHashCode();
If (statusCode > 400)
{
e.WebTest.Context["TransactionFailCount"] = 1;
}
}
public override void PostTransaction(object sender, PostTransactionEventArgs e)
{
int transactionFailCount = Convert.ToInt32(e.WebTest.Context["TransactionFailCount"]);
if (transactionFailCount > 0)
failCount = 1;
else
passCount = 1;
...
base.PostTransaction(sender, e);
}
public override void PostWebTest(object sender, PostWebTestEventArgs e)
{
base.PostWebTest(sender, e);
}
Thanks

Answer 1

A Web Performance Test (WPT) will continue to execute after an error is detected unless the Stop on error property of the test is true. It is possible that some aspects of a the handling of a request are not performed after an error, but I have not seen any such cases.
Be careful of terminology. WPTs use "transactions" as a way of grouping several requests. The context (right click) menu of a request has an "Add transaction" entry that selects a range of items in the test to be included in that transaction. Perhaps you should be using the PostRequest or PostPage plugins rather than PostTransaction.
I recommend that you do some experiments with a simple two or three request WPT plus some simple plugins that just announce that they have been called. For example
public override void PostRequest(object sender, PostRequestEventArgs e)
{
e.WebTest.AddCommentToResult("PostRequest called for url " + e.Request.Url);
}
Additionally, there is a good explanation of how and when plugins are called in pages 32 to 44 of the Visual Studio Performance Testing Quick Reference Guide from Codeplex.
The statement statusCode = e.Response.StatusCode.GetHashCode(); is strange. The value of e.Response.StatusCode is an enum, it integer value can be obtained by casting. The GetHashCode method is not intended to get the numeric value of an enum. The statement would be better as statusCode = (int)e.Response.StatusCode; or the assign and test (note that if is used for conditionals in C#, not If) might be better as
statusCode = e.Response.StatusCode;
if ( e.Response.StatusCode >= System.Net.HttpStatusCode.BadRequest ) { ... }