Using K6 and HAR to automate load testing.

We all have used k6 for load testing and are used to writing scripts for it. Currently I faced a challenge of leveraging the already present Rest Assured tests and use them to automate a script for load testing.

It is not crazy as it sounds. After a bit of research, I got a hang of it. Let me take you through how to achieve it.

• First and foremost, get you tests ready and make sure they are running. 😉
• Now, I have created a repo where there is a Dockerfile that takes care of running the proxy server and running a script that starts it. The link to my GitHub repo.
• Clone the GitHub repo and navigate to the folder [k6-with-har] and run the following command:

docker build -t har-proxy .

• This will build an image and then you can run the container using following command:
• Create a directory ‘hardata’

docker run -it -p 9000:9000 -v $PWD/hardata:/opt/har-data har-proxy

• This will start the container and the proxy is listening at 9000 port.

# Its time to make changes to your code a bit.

• Configure your requests to use the proxy.

RestAssured.proxy("localhost", 9000);
RestAssured.useRelaxedHTTPSValidation();

• Run your tests, you can see the output where the above command is running.
• Once all the tests are done you can quit the command.
• The output file will be there in your created directory `hardata` as `http.har` .

# Lets now convert the .har file to k6 script.

• First download the har-to-k6 tool.
• After the installation is done, run the below command to convert it to k6 script.

har-to-k6 http.har -o loadtest.js

# Now it's time to modify the script generated by the above command.

• According to your use case you need to make changes to the code. For example: If your requests are passing any sensitive data such as tokens then you need to either remove them or change them into variable.
• Need to make sure no such sensitive data is there in the code and it is not uploaded to your repository.
• You can follow the detailed instructions given in the following blog:

Using the HAR converter (k6.io)

# Running the Script:

• The generated script has auto-generated a “functional” test. By default, this test runs with one virtual user and for one iteration.
• You can configure the load options in many ways, As CLI arguments while running the test:

k6 run --vus 10 --duration 30s loadtest.js

• As options in the script file.

export const options = {
  vus: 10,
  duration: '30s',
};

• You have many different options to configure the tests, check out the Adding more VUs guide and the Options guide.

# Now finally it's time to run the load test.

k6 run loadtest.js

You can see the output on the screen while the test is running.

• Now if you want different kind of reports to be generated of the k6 script you can checkout:
• For HTML report this blog.
• For other options you can take a look at this document.