Performance testing with Karate Gatling

What is Karate Gatling?

Github page of this project has the tag line API performance testing made simple. Simply put this should help in performance testing of the api test written using Karate by leveraging performance testing capabilities of karate. On reviewing the documentation available on GitHub following capabilities are listed:

• Re-use karate tests as performance tests executed by Gatling
• Gatling and scala required only for defining the load model
• Everything else can be defined in Karate 
• Karate assertion failure also appear in the Gatling report
• Anything that can be written in Java can be performance tested.
• Option to scale out over multiple hardware nodes or Docker containers

In this post we will see how to reuse Karate tests for execution using Gatling

We will see step by step on how to setup Karate Gatling performance tests. There are a few prerequisites for setting up your karate Gatling tests.

Prerequisites:

• JDK should be installed and available in path environment variable
• Maven should be installed and available in path environment variable
• Scala SDK should be available
• Initial setup of Karate has been setup
• If it has not been setup use this article Karate - Quick Start with Maven Archetype

STEP 1 - Verify if JDK is available in path environment variable

Open command prompt and type java -version and hit enter key 

C:\Users\Kalimoh>java -version
java version "1.8.0_251"
Java(TM) SE Runtime Environment (build 1.8.0_251-b08)
Java HotSpot(TM) 64-Bit Server VM (build 25.251-b08, mixed mode) IT should return the version of jdk installed
If not, you need to setup you path for JDK

Secondly verify by typing in javac -version and hit enter key

This should return the version of the java compiler and once again confirm that the path has been setup correctly for JDK
C:\Users\Kalimoh>javac -version
javac 1.8.0_251 java version "1.8.0_251"

STEP 2 - To verify if maven is installed correctly

Type mvn -v in the command prompt and hit enter

 
This should return the Maven version, Maven home, Java version and other details
C:\Users\Kalimoh>mvn -v
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f
Maven home: C:\Program Files\apache-maven-3.6.3\bin\..
Java version: 1.8.0_251, vendor: Oracle Corporation, runtime: C:\Program Files\java\jdk1.8.0_251\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

STEP 3 - Scala Setup

If you have already setup Scala, Skip this part and move to the next step
Setting up Scala using Intellij Idea IDE (Community edition) is pretty simple

• Install Scala Plugin
• Within Intellij Idea Go to File > Settings > Plugins
• In the Marketplace search for Scala
• Click Install
• Click Apply and then Ok
• Create New Project and Download Scala SDK
• Click on File > New > Project
• In the New project window 
• Select Scala in the left hand pane
• Select Idea in the right hand pane
• Click on Next 
• Project details 
• Project name - HelloWorld
• Choose a Location
• JDK is selected by default
• Scala Sdk is empty
• Click on Create Button
• In the Select Jar's for new Scala SDK click on Download
• Select the Highest Version
• Click on Ok
• Click on Finish
• Wait for the Project to Load
• Verify Scala installation
• Then click on File > New > Scala class
• Type name as Hello
• select Type Object
• Modify the code to

Right Click on it and select Run 'Hello'
Hello, World! will get printed in the Run window
This completes the Scala setup, close this project and open the KaratePractice project

STEP 4 - Create a feature file and Scala class file

Create a new directory under src/test/java
Name this directory as performance
Within this directory create GETSingleUser.feature

This is a simple API test that will perform a GET call to the 'api/users/2' endpoint and will verify that it returns Status code 200
Right click on this file and Run it to make sure your api-test is working correctly
This will be re-used for running the performance tests

Create a new Scala class file and name it as UserSimulation.scala
Now let modify the pom.xml file (we will add code later )

STEP 5 - Modify pom.xml file

From the Karate Gatling page Copy the MAVEN dependency and add it to the the pom.xml file
Wait for the dependency to be resolved (In case you have not set to Auto resolve this will need to be done manually)
Then add the following within the plugins section
Wait for auto-resolve to complete. Take a note of the comments in case you are facing maven errors while adding the plugin.

STEP 5 - Add code to  UserSimulation.scala

Add the following code

• First add the import statements
• Then create a variable GetSingleUser
• Add a scenario name (I've copied it from the feature file created earlier)
• Specify the path to the feature file created earlier 
• Then within setUp we have defined the number of user to ramp up and duration in seconds. 

STEP 6 - Run

 In the IDE open Terminal. Then type the command mvn test-compile gatling:test

 Once the execution is completed you, should see a BUILD SUCCESS

Here's a video from my YouTube channel to help you with setting up API Performance testing framework with Karate Gatling

STEP 7 - Reports

Navigate to target\gatling\usersimulation-date directory 
In this directory there would be index.html file 
Right click on this file and select Open in Browser

Gatling Stats - Global Information

 

Gatling Stats - GET api users 2

References / Resources:

Karate Gatling 
Gatling cheat-sheet 
GETTING STARTED WITH SCALA IN INTELLIJ 
Wikipedia - List of HTTP Status codes
Code Repo on GitHub