Load Testing: Use of Assertion (Response and BeanShell) in JMeter

A common mistake in software development is we emphasize so much on functionality that we sometimes disregard the importance of performance of web applications. The end-result is the web application, in spite of having exciting features and fascinating UI, is turned down by client. Therefore, load testing is no more a secondary priority. I use JMeter, a very well-known open source tool, for load testing. Unlike Selenium, which is a functional testing tool, JMeter works at the HTTP requests and responses level. Therefore, when running a test in JMeter, we don’t see what’s happening in the browser. This is why assertions are very important to ensure that the test passes at every level and the browser is doing what it is supposed to do. Here are few examples of how to use assertions. I mostly use Response Assertion and BeanShell Assertions. I am going to show their usage here.

1.    Response Assertion: This is pretty simple yet very affective. And this is probably the most commonly used assertion.

Example 1: From Main Sample

Suppose you login to a site and upon successful login you are redirected to the home page. At this point of your load testing you want to ensure that the login was successful during load testing and the response to login HTTP request is the homepage. Consider the following example

Suppose “John Miller” is signing in to the site. And the welcome page greets him by his name. Now the assertion here would be to check if the text “John Miller” exists in the response of login HTTP request. You can do the following

Step 1: Identify the Login HTTP request. This would probably look like the following

Step 2: Add a Response Assertion as a child of this request a shown below.

i.                    Give it a name for better reference

ii.                  Select “Main sample only”

iii.                Select “Text Response”

iv.                 Select “Contains”

v.                   Use Add button to add one or more verification text

Step 3: Run the test. If things goes wrong you will see an error in “View Result Tree” listener as shown below

Example 2: From JMeter Variable

Consider the above example. Suppose you do not want to verify the homepage by the user name rather you want to verify by its title. Suppose title in home page looks like this

You can follow the following steps to accomplish this.

Step 1: Identify the Login HTTP request.

Step 2: Add a Post Processor Regular Expression Extractor as a child of this request. Add this before the response assertion as added in previous example.

 

Step 3: Change the response assertion as shown below

i.                     Select JMeter Variable

ii.                   Add the reference name of the variable added in previous step

iii.                  Provide the title

Step 4: Run Test.

2.   BeanShell Assertion: This is not as simple and straightforward as response assertion. But it offers more flexibility to add customized assertions. I personally use this quite often.

Example:

Consider the same example we used above. Suppose you have successfully logged in and you are visiting homepage. The homepage contains 4 meta-tags that you want to ensure are present every time a user visits the page.

(This is just an example to keep it simple. You may find a better usage in real life.)

Step 1: Add a BeanShell assertion as a child of the login HTTP request. And add the following code there

If you notice, it’s a simple java code that does the followings

i.        Get the entire response text

ii.      Looks for appearances of “<meta” text in the response text and counts the appearances

iii.    Finally fails the test if count does not match 4.

Step 2:  Run the test.

Of course, the above can be accomplished without using BeanShell assertion. However, this is an example of how flexible BeanShell assertions can be and how you can use it at your will.

Try this. There are other assertions as well. Once you get started, you may want to explore them as well. Thanks for reading.