JMeter Beginner Tutorial 3 - How to use Assertions - YouTube

Hello everyone and welcome to this session on JMeter Beginner Tutorial this is the third

session of the series and in the earlier two sessions we saw how do we install and setup

JMeter on Windows as well as on a Mac machine and we also discussed that because JMeter

is a Java application and therefore it is independent of the platform and operating

system.

So it does not matter whether you are using JMeter on a Windows machine or on a Mac machine,

it will work exactly in the same way on both operating systems, the only difference that

we saw was the way we start JMeter on Windows and on Mac.

Okay.

So in case you have not seen the earlier sessions, I would request you to go back and see those

sessions because they're very basic and deliver you know, step-by-step how to install and

you start using JMeter.

In the second series, we'll also see how we can create a very simple test plan and how

we can create a performance test for a web application of your webpage.

Now, this is the third session and this is for assertions, and assertion in very simple

words is our check on the response.

So when you send a request to the server, we get back some response and if you want

to do some checks on the response whether that response called you want to check whether

we have received 200 response code or we want to check some texting the response we may

also want to test the format of the response or we may want to test the duration of the

response that time it took to send that response or you can also check the size of the response

right, so there are various checks we want to do want response and all these checks are

called is assertions.

Now in JMeter let us go to our test plan so this was a test that we created in our last

session, and this is my Thread Group.

We are doing the test on this application lifecharger.org.

And we had added two listeners one is the View Results in Table and View Results in

Tree.

Now if I have to add assertions, I go to my Thread Group which I have named Users, do

a right-click, Add, and assertions.

And we can see there are a lot of assertions available in JMeter.

In the session we are going to focus on the very commonly used and very basic assertions

and in this list response assertion is the most commonly used assertions so I click here

and I get this window for Response Assertion.

So let me also write it down here, the first assertion is Response Assertions.

Now if you look at this window of Response Assertion, you have the option to apply this

assertion to “Main sampe and sub-samples”, “Main sample only”, “Sub-samples only”

and there is some “JMeter variable” we'll talk about it later maybe in some later sessions

but just to talk about the very basic use of this assertion.

Now the second option is Response Field to Test.

So in this case I want to test the response code that the server returns.

You can also test some text in the response or some document and so on, and I want to

check whether the response code equals too and I can write the code here.

So I am writing 200 so click this add button and I mention 200 here.

So what this assertion is going to do, it will check the response code and compare with

200.

If this matches it will pass it otherwise it will fail.

Let me make it 5 users and Ramp-Up Period let’s say 1 second and I just want 1 repetition.

So let me start this and you can see the results have generated

here , in the Tree as well and everything is in green that means it has passed, right.

And I can also cross verified by going to the Results Tree and we can see this is 200

and every response given 200, right.

So that means my assertion has passed.

Now what happens if the session fails?

So to deliberately fail the assertion, what I'm going to do is, I'm going to make it something

else let’s do 201.

So now it should fail because the server is giving back response code 200 and I am expecting

201.

So let me run this again and let us see the results now.

So you can see everything is in red.

Here also everything is in red and if I expand this you can see this same response assertion

failure and it is clearly telling us that we expected 201 but it receives 200 so that

is why it's a failure.

So this is how you can test the response assertion and to give us a better view of the sessions

results we can Add a Listener called Assertions Results.

So if I run this again and see at the Assertion Results you can see every time an assertion

fails our result is locked here and we can see what is a failure.

Comparison is 201 and received 200 so it's a failure.

So let me revert it back to 200 and see what happens now.

I’ve done it again, now you can see in the Results Assertion results I'm not getting

any exception and I'm getting all clean here as well as in the table also everything is

clean.

So this is what Response Assertion is and this is how you can use it.

Let us see the second assertion and that will be: Duration Assertion.

So this is also a very commonly used assertion: Duration Assertion so as the name indicates

duration is we are checking the duration of the response and again we can apply it to

“Main sample and sub-samples” and so on and if I say let me first quickly look at

the duration I'm getting a duration of around 1.5 seconds this is a millisecond so you can

1.5 second let me say let me put here 1500 which will be 1.5 seconds this is in milliseconds,

right.

So any response which takes more than 1500 milliseconds will be a failure and we will

get notified in the Assertions Results.

So let me run it again and let us see if we get any response beyond 1500 millisecond and

yes there are I think all the response took more than 1500 milliseconds that's why everything

is in failure and you can see this is the Duration Assertion failed.

“The operation lasted too long” it took 2169 milliseconds but should not have lasted

longer than 1500 milliseconds, right.

So let me change the duration and say this is 2200 milliseconds and run it again.

Let me see, this time everything passed, because all the response was less than 2200 milliseconds.

If I again make it 2000 millisecond and run it let me see if anything fails.

No still everything was less than 2000 milliseconds, right?

So now this is passing.

So this is how we can have our Duration Assertion and the check on the response time.

The third Assertion that we are going to see here is

Size Assertion which is also quite commonly used Assertion in JMeter.

So Size Assertion as the name indicates it is it has to do something with the response

size.

Now if we see our worth size in bytes is somewhere around 30235 bytes.

So let me say 30235 and equals to.

So if my size in bytes is equal to this particular number then it should pass, else it should

fail and I can have multiple comparisons here.

So let me run it again and see if all the Size Assertion passes or not.

And yes I have got one failure and you can see “The result was the wrong size: It was

30228 bytes, but should have been equal to 30235 bytes”,right?

And if I go to my Results Tree I get the same message here.

The other requests also fail because of some other assertion failure which is like the

Duration Assertion in most of the cases.

Let me make the Duration Assertion some higher number so that this does not fail and run

it again.

OK, so now we can see there are only 3 failures and they are due to the Size Assertion and

the same thing is displayed here as a well as in the results tree so there is all 3 failures and all failures are

due to the Size Assertion.

So this is how we can check the size of the response and obviously, I have already made

a strict check by selecting the equals option we mostly select either greater than or less

than or greater than equal to or less than equal to.

So if I say the size should be greater than or equal to this particular number and run

it again, let me see this time what happens.

See, this time everything passes.

This time all the Assertions passed so we're seeing all green here.

So this was the Size Assertion.

The next Assertion, that we're going to see is “HTML Assertion”.

The fourth Assertion is HTML Assertion.

So what this means is we are going to check the format of our response and it is actually

going to check that the format is a valid HTML or not.

In case it is not a valid HTML it will throw out some address and it will fail that Assertion.

So if I run this test now, see we have a failure for HTML Assertion and it is saying there

are 38 errors and 110 warnings.

Now if you go back to your HTML Assertions you can actually provide a threshold for the

errors as well as warnings.

So let me say that my threshold is 38, if there are errors more than 38 it should fail

it should give out a message a re-message and 110 other warnings.

Let me run it again, now this time it did not fail, because I have affiliates in the

HTML format but the failures are 38 and 110 warnings and I have made the threshold equal

to that, in case I make it 37 and let me make it 109.

This time it must fail.

So we can see, there 38 errors and 110 warnings allowed at 37 and warnings allowed 109 so

there's a failure and we have caught the results here the same we can see in the Tree View

as well.

Now here is the thing, this is telling us the number of errors, number of warnings but

where exactly is the error and what element is missing or what note is missing we are

not aware of that right?

So to get a report on that, what we can do is we can actually write this report to a

file and you can see this is the filename we can browse it and let me say I'm giving

I want to store all the you know errors here and I can say errors only.

So it will only log the errors and now if I run this, so here are the errors and if

I go to this file, so this file is here.

Now you can see the test given us all the you know errors, what was missing.

This is not nice: “discarding unexpected <header>” and all those things so this is

a very good test to validate your HTML and in stand-alone web application this might

not be a very, you know, concerning thing but if you're web applicant has to you know,

partner with 3rd party apps and they have to talk to each other, then these issues can

be very big and you will have to resolve this right.

So JMeter provides us this way to check out XML, HTML and so on.

Similarly you can see we can check do I check on XML on or XHTML as well so if I select

XML and do the same run.

So here everything passed.

So you can do a check on XHTML as well and this HTML, right?

So this was a HTML Assertion.

Let us look at some other Assertions.

There is XML Assertion as well so again XML Assertion will check the format and if it

is a valid XML then it will pass otherwise it will fail so we can say this is a check

on the XML format, right?

So see, XML Assertion is failing and it is saying “The entity “raquo” was referenced,

but not declared.”.

And again you can write this Assertion to a file as well and you can make a check on

your XML and you can actually fix this thing, right?

Whatever is the Assertion failure you get in your web app.

One other Assertion that we should look at is XPath Assertion.

Now XPath Assertion will mostly be used in API testing so we'll be having a dam on API

testing with JMeter in the coming sessions and then there will be you know, looking at

how exactly we used XPath Assertion for now I'll just explain that you know, in the response,

if you want to check some particular node or some particular XPath or some value at

some particular XPath, we can use XPath Assertion.

So XPath Assertion, we will look into more details in the coming sessions but just for

you know our basic understanding we want to assert some XPath or some value or some node

in the response and we can use this.

So these are all the Assertions or I should say the most commonly used, or the most basic

Assertions which we should be knowing to use JMeter sessions.

One thing is that you should take carer's when you add a listener for Tree and you add

a listener for a Assertion Results these listeners take up a lot of memory, so when you want

to put the same test on load, maybe you can disable these listeners but if you want to

do a check on your application format and other things, you can add this listeners,

otherwise you can you know just drop these listeners or disable them.

So this was all about basic Assertions in JMeter.

In the coming series of this tutorial we will look at various types of listeners in JMeter.

So that's all about Assertions in JMeter.

Hope you like it , thanks a lot. :)