Load-Testing ASP.NET MVC (Part 3 - JMeter (slightly more) advanced)

Part 1 - Apache Workbench
Part 2 - JMeter introduction
Part 3 - JMeter (slightly more) advanced

As promised, in this post I'm going to explain some more JMeter stuff. So, I'll show how to:

• Submit information (HTTP POST)
• Handle authentication
• Particularly in the ASP.NET MVC context
• Read information from a page and store it in a variable
• Particularly to read the ASP.NET MVC anti-forgery token
• Vary the posted data by reading it from a CSV file

Also, I'll include some extra elements to make the test more maintainable and professional.

So, again, lots of ground to cover so lets get started.

First, we need to create the application that will be tested. It'll be pretty simple: a login screen and a form with a bunch of fields. After submitting it should show a success or error message according to the validation.

So, this is the login screen:

After supplying the correct credentials (meaning, password = "password") a page is opened with 2 fields ready to submit feedback.

The page has validation set up

And after filling the two fields correctly a message appears and the form fields are cleared so that new feedback may be supplied.

That's it. Now, there's some small details to take into consideration.

• The web page has Forms Authentication. Pretty standard stuff: if the credentials are valid then create the authentication cookie.

• I'm using an ASP.NET MVC mechanism to defend against Cross-Site Request Forgery by supplying a token in the HTML Form that must be sent on the POST. This is done by using the ActionFilter [ValidateAntiForgeryToken] on the action and a @Html.AntiForgeryToken on the view. So, if a POST request does not include the anti-forgery token the server will reject the request and throw an exception. 

Let's create a pseudo-representation for our test-plan:

For each User
 |
 +--- Login
 +--- Repeat n times
         |
         +--- Submit Feedback
         +--- Wait a couple of seconds before submitting again

This will roughly translate to:

Now, as this is the second post on JMeter I'm going to jump some hoops and show the final test plan and then explain each of the elements.

This might seem a little scary but most of the elements should be really easy to grasp. I'm going to show the configuration for each one:

Test Configuration

It's really useful to have all the configuration in one spot, typically at the start of the test. This way we can tweak stuff more easily.

HTTP Request Defaults

Instead of repeating the server and port on each request we can define defaults for those values. This is really a time-saver, particularly when switching environments.

HTTP Cookie Manager

The cookie manager is the only thing required to handle forms authentication. It makes sure that the authentication cookie is there, making your requests authorized after the login.

For Each User

Normal thread, but using variables instead of hardcoded numbers. The Loop Count is 1 because we have a Loop Controller inside.

Login

The login is a simple post to a specific action on our website. The username is always supplied as "DummyUser" with a "password" password.

Notice that the server name and port number are empty, as we're using the HTTP request defaults.

Open Feedback Page

Just opening the feedback page before submitting. This is required because of the next action. 

Regular Expression Extractor

The Request verification token is a hidden value in the form. Something like:

<input name="__RequestVerificationToken" type="hidden" value="........"/>

We have to load that field into a JMeter variable. Thus we use a Regular Expression Extractor, passing the following regular expression:

name="__RequestVerificationToken" type="hidden" value="([A-Za-z0-9+=/\-\_]+?)"

Repeat

Pretty self-explanatory. Repeat n times for each user (thread).

Load data from file

It's a good idea to have diversity on your tests. Thus, instead of having hardcoded values, we can read values from a CSV file and assign them to variables. These may then be used normally in JMeter.

For example, I've created a csv file, named "Feedback.csv" with this content:

Nice Site;I really enjoyed that movie
Pretty good;I liked it, but there's some stuff that I didn't really getAwful;This is the worst piece of **** I've ever seen
Interesting;Nice stuff
(...)

much more lines. Should be enough to fulfill the number of users * number of requests.

One thing to note is the Sharing mode. With "All threads" it means that each request for each user will choose a new value from the csv file.

Submit Feedback

This is where the feedback itself is submitted. Notice that all the values use variables and that the Request Verification Token is also sent.

Check Result

Just checking if the response shows a success message or not.

Wait Before Next Request

If we're simulating real users, we want to wait a little bit before issuing another request. I like the Gaussian Random Timer a lot because the value is a "controlled random" as it follows a normal (Gaussian) distribution on the test-plan as a whole.

The scary part is that JMeter provides much more stuff than what I've shown here. Anyway, I'll wrap up things for now. If you've got any doubt/suggestion place a comment.