A Guide to Performance Testing
By Shreya Bose, Technical Content Writer at BrowserStack - January 18, 2021
What is Performance Testing?
Performance testing is a software testing tactic 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.
Performance testing is integral to ensuring that software operates at expected quality levels at all times. It aims to evaluate the following:
- Application output
- Data transfer speed
- Speed of data processing
- Usage of network bandwidth
- Maximum number of simultaneous users software can support
- Magnitude of memory consumed
- Command response times
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 a 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.
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.
How to Conduct 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, performance tests can be conducted to 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.
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 the tests
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
Self-explanatory. 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.
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 performance 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 performance 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 performance 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. Performance tests 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 performance 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, performance 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 performance tests.