Locust is a modern load and Performance testing software that is a drift from the traditional load testing of code. Locust is great for high-scale testing and allows test case developers to write tests to simulate users’ behavior on mobile apps or any other kind of IoT device. Locust is great as it allows for testing on different operating systems and platforms, and it is also open source which employs high flexibility. In this article, you’ll learn more about Locust and how it can be used for mobile app testing.

Using Locust for load testing

Load testing is an aspect of performance testing where an application response is tested to ascertain how much load it can sustain, i.e., how many users can access the application simultaneously without any problem. Testing the varying load conditions is necessary to appraise the speed and capacity of the application.

How Locust works for testing mobile applications

The Locust test is simply a representation of multiple users on your applications (Locusts) with different behavior on the application. This simulation of multiple behavioral uses makes it easy to identify real-time lags in performance and other hindrances in these scenarios. With this, the developers can identify aspects that need to be addressed and altered for better performance

Advantages of Locust for app testing

• The Locust tests are written in simple python language
• Clear and comprehensive documentation
• Each user is represented as a greenlet, and many users can be represented at a single time
• It allows multiple test scripts to be run to quickly detect and confirm performance and load handling issues.
• It is a web-based software with an intuitive interface and an open source, making it highly accessible.

Disadvantages of Locust for app testing

• No capture and save, and all tests need to be done manually
•  A locust load test chart is not persistent. Charts are reset on refreshing.

How to use Locust for load performance testing

Before starting, python and an updated version of Locust should be installed. On the official documentation, You will find the detailed installation steps.

Writing a Locust Load Test: Writing a locust load test to run the test cases for your applications involves the following steps.

1. Import the HttpUser, task, time, and between classes.  
2. Create an AuthenticateUser class which takes as an argument the HttpUser class that was imported in the previous step.
3. Create a variable caller timer to place  10 seconds within the subsequently executed task.
4. Create a function that will stand for the registration and login process called authenticate_task.
5. Implement a method called on_start that will be executed at the beginning of the test file.