What is regression testing? What regression testing tools are available? How do you perform regression testing? We're here to answer all your burning questions in our ultimate guide.
Regression testing is among the most important parts of your overall testing suite and among the most well-known types of test. Here’s our breakdown of the best practices, the failure categories, and how to get started with regression tests. If you want to get started with regression testing with Global App Testing, you can do so here.
Recap | What is regression testing?
Regression testing is a type of QA software testing that ensures changes or updates to an existing software product do not affect previously functioning features. A regression test asks, “does everything still work as expected?” A malfunction or bug in another part of the system caused by a new release is called a “regression” – hence, “regression testing.”
A dev team is generally expected to run a regression test suite at the end of a development sprint, but they can also perform regression testing during development as part of your CI/CD pipeline in an agile testing environment. How often you should execute regression tests depends on the incentives for your business and the difficulty of the test.
Why is regression testing important?
What regression tests identify – that your existing functionality continues to work as expected – is likely to be extremely important for your business, making regression testing an important defence against against severe risk.
It can also surprise unseasoned developers to see how likely that risk is to occur. Even tiny changes to the code can have outsized and unexpected impacts on completely separate elements of the product. So the risk frequency is higher than you might expect.
It’s also much less severe outcome for the business to release broken new functionality than it is to break things upon which people already rely. As businesses shift from startup to scaleup, it becomes more impactful to prevent regression than to add new features quickly. To break an existing feature is massively disruptive, and will cause a huge headache for your CS team. So the larger your user base, the more important regression testing becomes.
Regression testing is also one of the most common types of test your business conducts, meaning that it’s also important to think about regression testing in operational terms. Done wrong, it can stack up significant cost to your business and can slow your CI/CD cycle down.
How is regression testing different from… re-testing, unit testing, functional testing
Retesting is where you search for a specific defect you’ve recently found (and perhaps fixed). Regression testing is where you search generally for a defect across the product following a new feature release.
As per unit and functional testing; regression testing isn’t a technique, but an outcome, so all kinds of different tests are appropriate to include within a regression testing suite. That’s almost certain include functional tests and unit tests – and the majority of regression tests are functional test case execution – but might also include any other kinds of test.
Courtesy: Keizo Tatsumi
How to prioritize your test cases for a regression test
One of the methodologies for regression testing is “retest all” – which is what it sounds like, a complete re-execution of all of the test cases on your system. This is time intensive and expensive. Instead, businesses are more likely to choose a selection of test cases and execute on them.
How many test cases?
It is not possible to answer “how much” regression testing you should do and how often, (although as a testing company, we generally argue in favour of a proactive and thorough testing approach).
Instead, we’d recommend identifying two or three distinct regression suite tiers and calculating their cost and impact level. Ensure you can calculate both the time and the cash cost of executing each tier of test suite so that you can refer quickly to your figures at the decision stage. This will enable your business to choose the appropriate depth for the moment and encourage you to keep track of what level of testing you are conducting in general – and whether that aligns with your budget and risk appetite.
What kind of test cases?
Once you have made the decision not to “retest all”, you will be confronted with the question of what test cases to prioritise in a given regression suite.
Again, this is often specific to your own business and product. But we’ve seen our clients use the following values to prioritize test cases in their regression suites.
Thinking about automation in regression testing
Regression testing can be done manually or with the help of automated testing tools.
Manual regression testing involves manually retesting the software after changes have been made. This can be time-consuming and may require a large team of testers. Automated regression testing, on the other hand, uses software tools to retest the software automatically. This can be faster and more efficient than manual testing, but it requires specialized skills and expertise to set up and maintain the testing tools.
Developers tend to like the idea of automating tests, and as one of the biggest test categories, regression testing is one of the biggest targets.
But there are challenges to test automation:
Global App Testing is a crowdtesting platform - we send tests to a network of human testers around the world (like “Uber for testing”) and you receive them back in less than 5 or less than 48 hours, depending on the level of specialism.
That means that if you’re struggling to try to automate more of your tests, Global App Testing lets you simulate the speed benefits of automated testing without demanding the automation work from your engineers. In fact, we actively help businesses close their “automation gap”.
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Source: Dan Ashby
Best practices & failure categories for regression testing
Common failure categories of regression testing
Regression in agile
In an Agile or DevOps workflow, software development teams must balance the need for rapid releases with the need for thorough testing. Regression testing can be a bottleneck in this process if not managed properly. However, there are ways to regression test effectively without slowing down the development process. In this section, we'll explore how you can regression test in an Agile or DevOps workflow without it becoming a bottleneck.
1. Automate Your Tests
One of the most effective ways to speed up regression testing is to automate your tests. Automated testing tools can help you execute test cases quickly and accurately, freeing up your team to focus on other tasks. Automated tests can also be integrated into your DevOps pipeline, allowing you to catch issues early in the development process.
2. Prioritize Your Tests
Another way to avoid regression testing becoming a bottleneck is to prioritize your tests. Prioritizing your tests based on their criticality can help you focus on the most important features and functionality, ensuring that they are thoroughly tested. This approach can also help you save time and resources by avoiding testing less critical features and functionality.
3. Use Parallel Testing
Parallel testing involves executing multiple test cases simultaneously, which can help speed up the testing process. This approach is especially useful for large-scale regression testing, where executing tests sequentially can take a significant amount of time. Parallel testing can be achieved using automated testing tools and can help you catch issues quickly and efficiently.
4. Embrace Continuous Testing
Continuous testing involves testing throughout the development process, rather than just at the end. This approach can help you catch issues early and avoid regression testing becoming a bottleneck. By integrating automated testing tools into your DevOps pipeline and continuously testing your software, you can ensure that your software is reliable and bug-free.
Regression testing tools
There are a large number of tools available on the market to help you undertake a regression test.
We’d love to give you a personal demo of our platform. Find out how we manage, execute and analyse test results to help you release high quality software anywhere in the world.Ready? Let's talk