How, Why & What Is Stability Testing ?

What is Stability Testing?

Stability testing is a non-functional type of testing that usually comes under performance testing. The main focus is to determine the software’s stability when exposed to heavy load, stress, and different environments. It does not verify the normal behavior but the point when software crashes, which is known as the system’s breaking point. It is also referred to as soak testing and is time-based testing where performance is measured over time. The load is applied to the system under test over a long period of time, which helps determine how stable the software is.

Why Should We Perform Stability Testing?

  • Software developers have a fear of making a lot of changes in the system because they do not want to break the software. This fear is very well taken care of by stability testing.

Advantages of performing stability testing on the system under test

  • Provides the limit of the data that could be handled by the system practically.
  • Gives confidence in the system’s performance
  • Determines the stability and robustness of the system under load
  • This leads to a better end-user experience.

Disadvantages of not performing stability testing on the system under test

  • The system slows down with a large amount of data.
  • The system crashes abruptly.
  • It behaves abnormally when taken to a different temperature or attached to a different voltage.
  • The system’s performance decreases, which in turn can have bad effects on the business.
  • Stability testing should be carried out before giving a green flag for pushing the system into the market to avoid all the above issues. Since it is time-based testing, it is crucial to know the time limit required to carry out the whole testing process. We would not want to cross the testing deadline.

How To Perform Stability Testing?

Stability testing can be performed using tools (Automation) and manually tested.

  • Let me explain this as an example.

The smartphone is a perfect example of stability testing. When the handset is loaded with the latest developed software, the first thing that is tested is booting, and then regression or smoke testing is carried out. Once the first level of testing passes, functional and non-functional testing is carried out. Functional includes execution of all the functionality-related test cases, and non-functional or performance testing includes load, stress, stability, and reliability testing.

Now, for testing the performance, we have the following aspects to look at:

  • Memory is 60% filled with data, and the system is tested for performance.
  • 0% of the memory is filled and then tested again.
  • Tools like Load Runner are used to load the system and then test the stability.
  • Automation scripts can also be run to fill the system’s memory and to test the performance.

Some of the examples are:

  • Clicking on a particular button 100 times, sending 1000 requests to the system simultaneously, pressing random buttons, opening and closing some downloaded applications, etc.
  • Battery life and performance can also be tested; sometimes, the software loaded on the handset decreases battery life unexpectedly.
  • The maximum allowed load is applied to the system, both internally and externally, to determine the breaking point.
  • Stability testing needs a proper test environment with the required tools and structured approach for high effectiveness.
  • If the system crashes while testing, the time it takes to recover from the crash also determines the performance in handling negative scenarios.

Stability vs Reliability

Often, people get confused about stability and reliability. They are quite different, but they both come under performance testing.

For instance, we have an application that works perfectly, except that it crashes every 5 minutes, but it’s up instantly without any data loss. That would be considered reliable but not stable. I can rely on it to not lose important data and work correctly even though it is unstable.

Like the internet, it is far from stable; we can see connections drop and reappear, packets collide and are lost, and other unstable things happen. However, it’s pretty amazing how reliable it is given all its inherent instability.

Someone might refer to a system as stable but unreliable if it is always up and running but intermittently produces incorrect results or occasionally loses data. When software is stable and reliable, it is considered high-quality and performance.


Software systems with simple architecture are considered more stable than software with complex architecture. Simple architectures are easier to understand and modify, which minimizes the time spent understanding the system and making required changes, maximizing software stability.

Time plays an important role in stability testing, as a system that performs well for a long duration of time is considered a high performer.

I love open-source technologies and am very passionate about software development. I like to share my knowledge with others, especially on technology that's why I have given all the examples as simple as possible to understand for beginners. All the code posted on my blog is developed, compiled, and tested in my development environment. If you find any mistakes or bugs, Please drop an email to, or You can join me on Linkedin.

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