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Performance Testing: A Detailed Guide

By Shreya Bose, Technical Content Writer at BrowserStack -

Table of Contents

What is Performance Testing?

Performance testing is a type of software testing for evaluating how a certain software performs under variant conditions. Performance, in this case, refers to multiple variables: stability, scalability, speed, responsiveness – all under numerous levels of traffic and load.

As an example, let’s say you are developing a gaming app. Before releasing it, you must run a performance test to ensure that it operates at expected quality levels as it is intended to, irrespective of the hardware or software environment it is in. Within the test, the app must:

  • Load and play at high speed.
  • Render all visuals and text as intended.
  • Supports multiple players – if it is a multiplayer game
  • Uses minimal memory (no more than is absolutely required).

This article will explore how to conduct performance testing, the various types of tests in this category, and some associated best practices to make the process smoother.

Types of Performance Testing

There are several types of software performance testing used to determine the readiness of a system:

  • Load Testing: Measures system performance under varying levels of load AKA the number of simultaneous users running transactions. Load Testing primarily monitors response time and system stability while the numbers of users or operations increase on certain software.
  • Stress Testing: Also known as fatigue testing, it measures how the system performs in abnormal user conditions. It is used to determine the limit at which the software actually breaks and malfunctions.
  • Spike Testing: Evaluates how the software performs when subjected to high levels of traffic and usage in short periods of time, repeatedly.
  • Endurance Testing: Also known as soak testing, it evaluates how the software will perform under normal loads over a long period of time. The main goal here is to detect common problems like memory leaks which can impair system performance.
  • Scalability Testing: Determines if the software is handling increasing loads at a steady pace. This is done by incrementally adding to the volume of the load while monitoring how the system responds. It is also possible to keep the load at a steady level while playing with other variations like memory, bandwidth, etc.
  • Volume Testing: Also known as flood testing because it involves following the system with data to check if it can be overwhelmed at any point and what fail-safes are necessary.

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Important Metrics for Performance Testing

The following metrics or Key Performance Indicators (KPIs) are helpful in evaluating the results of system performance testing:

  • Memory: The storage space available and/or used by a system while processing data and executing an action.
  • Latency/Response Time: The duration of time that passes between when a user enters a request and when the system starts to respond to that request.
  • Throughout: The number of data units processed by the system over a certain duration.
  • Bandwidth: The amount of data per second capable of moving across one or more networks.
  • CPU interrupts per second: The number of hardware interrupts experienced by a system while it processes data.
  • Speed: The time in which a web page loads with all elements – text, video, images, etc.

Quick Tip: Run website speed tests on SpeedLab for free. Simply enter the URL, and get a detailed report on your website speed as it runs on real browsers, devices, and operating systems.

How to do a Performance Test

1. Identify The Right Test Environment and Tools

Start with identifying a test environment that accurately replicates the intended production environment. Document relevant specifications and configurations – hardware, software – to ensure close replication. Don’t run tests in production environments without establishing safeguards to prevent disruptions to user experience.

The easiest way to test in real user conditions is to run performance tests on real browsers and devices. Instead of dealing with the many inadequacies of emulators and simulators, testers are better off using a real device cloud that offers real devices, browsers, and operating systems on-demand for instant testing.

By running tests on a real device cloud, QAs can ensure that they are getting accurate results every time. Comprehensive and error-free testing ensures that no major bugs pass undetected into production, thus enabling software to offer the highest possible levels of user experience.

Whether manual testing or automated Selenium testing, real devices are non-negotiable in the testing equation. In the absence of an in-house device lab (regularly updated with new devices and maintains each of them at the highest levels of functionality), opt for cloud-based testing infrastructure. Start running tests on 2000+ real browsers and devices on BrowserStack’s real device cloud. Run parallel tests on a Cloud Selenium Grid to get faster results without compromising on accuracy. Detect bugs before users do by testing software in real-world circumstances.

Users can sign up, select a device-browser-OS combination, and start testing for free. They can simulate user conditions such as low network and battery, changes in location (both local and global changes), and viewport sizes and screen resolutions.

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2. Define Acceptable Performance Levels

Establish the goals and numbers that will indicate the success of performance tests. The easiest way to do this is to refer to project specifications and expectations from the software. Accordingly, testers can determine test metrics, benchmarks, and thresholds to define acceptable system performance.

3. Create test scenarios

Craft tests to cover a number of scenarios in which the software’s performance will be challenged by real-world usage. Try to create a few test scenarios that accommodate multiple use cases. If possible, automate tests for quick and error-free results.

4. Prepare the Test Environment and Tools

This requires Configuration Management, which is essential to programming the environment with relevant variables before tests are executed. Ensure that the testers have all necessary tools, frameworks, integrations, etc. at hand.

5. Run the Performance Tests

Execute the previous constructed test suited. Adopt parallel testing to run tests simultaneously so as to save on time without compromising the accuracy of results.

6. Debug and Re-Test

Once test results are in and bugs have been identified, share them with the entire team. Consolidate the bugs and send them to the right developers to be fixed. If possible, QAs can fix a few basic bugs in order to save time and teamwide back-and-worth.

When the performance shortcomings have been resolved, re-run the test to confirm that the code is clean and the software is performing at optimal levels.

Performance Engineering vs Performance Testing: Differences

While this article has covered much of performance testing it is impotence to distinguish it from performance engineering.

Performance engineering uses best practices in every stage of the software development lifecycle to further optimization efforts and gain maximum efficacy. Generally, this practice comprises everything from UI/UX design, architectural configuration, code structure, and aligning technical specifications with business requirements.

  • In performance testing, testing creates test cases and runs them to check software operation levels. In performance engineering, engineers partake from the first stage of the development lifecycle to design steps for actually creating the software.
  • Performance testing is meant to uncover bugs and errors in software. Performance engineering takes bugs and seeks not just how to resolve them, but how to design the development process so as to meet industry standards and best practices.
  • It is possible (though not ideal) to run performance testing without coding and programming skills. However, performance engineering requires high-level programming capabilities to implement.

Of course, this is only a cursory glimpse of how performance engineering works, but it should prevent you from confusing or conflating the two terms, however synonymous they may seem at first glance.

Best Practices for Performance Testing

When running a system performance test, keep the following guidelines in mind:

  • Start at Unit Test Level: Don’t wait to run performance tests until code reaches the integration stage. Run tests on code before pushing them to the main branch. This is a DevOps-aligned practice, part of the Shift Left Testing approach. By running tests on each code unit, the chances of magnified bugs showing up in the latter stages decrease significantly.
  • Remember that it is about the User: The intention of these tests is to create software that users can use effectively. For example, don’t just focus on server response when running tests; think of why speed matters to the user. Before setting metrics, do some research on user expectations, behavior, attention spans, etc. Use that as the guidelines to decide acceptable software performance levels.
  • Create Realistic Tests: Don’t throw thousands of users at a server cluster and call it a performance test. It would stress-test the software, but do little else. Instead, consider the following: In the real world, traffic comes from a multitude of devices (mobile and desktop), browsers, and operating systems. Testing must account for this variety. With a platform like BrowserStack, this is easy to accomplish. Invest in research to identify the device-browser-OS combinations the target audience is likely to use, and run tests on those devices with BrowserStack’s real device cloud. Don’t start a test from a zero-load situation. In the real world, any system that an application is rolled out on will be under some load. The volume and intensity of load will vary, but it will never be non-existent.
  • Make it part of Agile: It is common to leave performance testing to the end of a development project. By then, bugs have metastasized and are enormously hard to fix. Not to mention, they cause significant delays in the project by tying up devs with errors that could be avoided. Fix this by making performance testing part of the Agile software development process. Integrate testing into development by including testers into brainstorming sessions from the beginning. Testers are likely to bring up performance testing and drive home the importance of conducting it as early as possible.

The importance of performance tests cannot be overstated. Since every software, website or app, essentially aims to serve and delight users, these tests are indispensable in any software development scenario. All the user cares about is how the software performs, and the only way to meet their expectations is to run the right tests.

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