What is Regression Testing? The Full Guide

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Regression testing is a critical aspect of software testing that ensures the reliability and stability of software systems after changes have been made. As software systems are updated, and new bugs are created, previously functioning features may stop working as intended. If you’re stuck on basics like, “What is regression testing” or “How do I use it in my QA strategy,” let’s start here.

Regression testing helps to identify these issues and prevent them from impacting users or damaging a company’s reputation. Whether you work in tech or another sector that relies on software, understanding regression testing is crucial to ensuring the success of your projects.

This post provides a comprehensive guide to regression testing, covering everything from the basics to advanced techniques. You’ll learn what regression testing is, why it’s essential, when it should be performed, and how to implement it effectively. We’ll also share insider tips and best practices that will help you to streamline your testing process and deliver high-quality software products.

What is Regression Testing?

Regression testing is a process that involves retesting a previously tested software product after it has undergone changes or enhancements. 

Regression testing aims to ensure that any modifications or additions to the software have not adversely affected its functionality or performance.

Regression testing covers a wide range of testing techniques, including functional testing, performance testing, and security testing. It also includes testing integrations between different software components and verifying data migration between systems. 

Types of Regression Testing

Several types of regression tests can ensure the stability and reliability of a software system. These include:

  • Unit Regression Testing: involves testing individual code units to ensure changes haven’t introduced new bugs.
  • Partial Regression Testing: a portion of the system is tested after minor changes.
  • Complete Regression Testing: testing the entire system after implementing changes; a more thorough approach and typically used after introducing significant changes.
  • Selective Regression Testing: a hybrid approach that involves selecting a subset of tests from the entire test suite to be run after updates have been made. These tests are chosen based on their relevance to the changes, and the goal is to ensure that any impacted areas of the system are thoroughly tested.

How is it Performed?

Regression testing is typically performed by re-executing previous test cases on the modified software system to verify that it still functions correctly. Test leads will examine what changes have been made to the code, isolate new features, execute test cases, and create bug reports to tackle issues. Manual regression testing—especially strategic, exploratory tests where skilled testers take on different product areas and approach the product exactly as a user would—allows for the most realistic mobile testing possible.

On the other hand, automated testing tools can expedite the testing process and ensure test execution. Typically, a hybrid manual and automated testing model is the best way to ensure comprehensive coverage.

Manual Regression Testing

Manual regression testing involves real humans executing test cases on a software system after updates, new features, or new ships. One of the main benefits of manual regression testing is that it allows testers to identify subtle issues that may be difficult to detect using automated tools. However, manual regression testing can be time-consuming and expensive, particularly for large and complex software systems.

Manual regression testing is best suited for scenarios where the software changes are minor, and the risk of introducing new defects is low. It may also be necessary for certain types of testing, such as user interface testing, which cannot be effectively automated.

Automated Regression Testing

Automated regression testing uses tools to execute previous test cases on a system after updates. One of the main benefits of automated regression testing is that it can significantly reduce the time required to perform regression testing, particularly for large and complex systems. However, automated regression testing is limited by the test cases’ quality and the testing tools’ effectiveness. It may not be able to detect subtle issues that manual testing can.

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Automated Regression Testing Tools

There are various automated regression testing tools available that can help streamline the testing process and ensure accuracy. Let’s explore some of the most popular tools on the market.

Selenium – Selenium allows testers to simulate user interactions, execute test scripts across multiple browsers and platforms, and provide robust reporting capabilities.

Ranorex – Ranorex facilitates regression tests by providing a user-friendly interface and an extensive set of features. With its ability to record, replay, and automate tests across various platforms and technologies, Ranorex streamlines the regression testing process.

WATIR – Watir stands out as a regression testing tool due to its ease in creating, managing, and running test cases. It boasts a user-friendly interface and is particularly suitable for beginners, thanks to its simplicity and cost-effective nature as an open-source solution.

Appium – Appium supports automation across multiple platforms, offers compatibility with popular programming languages such as Ruby, Python, Java, JavaScript, PHP, C#, and RobotFramework, ensuring flexibility in test runners and frameworks. Embracing the philosophy of providing a stable WebDriver-based interface, Appium stands apart from other automation tools, ensuring that tests remain uncomplicated even with upgrades.

These tools allow testers to automate the execution of test cases and identify issues quickly, saving time and effort. Automated regression testing tools offer increased efficiency, consistency, and accuracy, but they can be costly, with high initial investment and the need for ongoing maintenance.

How To Create a Robust QA Strategy

Creating a robust regression testing strategy combines manual and automated testing techniques to create comprehensive coverage.

Functional Vs. Regression Testing

Before starting regression testing, it’s essential to distinguish it from functional testing. Functional testing checks if a software system operates according to spec. Regression testing checks if any new changes have introduced unexpected bugs or affected existing functionality.

Performing functional and regression testing is essential, but they require different approaches. Functional testing focuses on testing the software features in isolation, while regression testing tests the whole package after changes have been made.

Fusing Manual and Automated Testing

When fusing manual and automated testing, define the scope of each type of testing and create use cases, test cases, and runs accordingly. Data analytics and bug reports can also help identify patterns and provide insights to improve the testing process.

In-House Vs. Outsourced Regression Testing

When it’s time for regression testing, you have two options: in-house or outsourced testing. In-house testing requires an internal team, which can be expensive and time-consuming. However, it provides the advantage of having complete control over the testing process and the ability to integrate testing into the software development life cycle.

Outsourced testing involves hiring a third-party provider to handle the testing process. This can be cost-effective and convenient, as the right provider can offer an expert team and the latest testing tools, but choosing the right partner is essential.

Ultimately, deciding which to use depends on budget, timeline, and internal expertise. At Testlio, we offer the best of both worlds – you can choose from both in-house and outsourced regression testing services so you can build your ideal scenario.

Quick guide for deciding whether to build an in-house QA testing team vs hiring a testing partner showing considerations on cost, productivity, capacity, platform, and devices.

Regression Test Cases

Regression testing requires specific test cases to ensure the software functions as intended after updates. Test cases should be designed to cover all possible scenarios and validate that no functionality is lost or impacted by the changes.

Practical regression testing test cases should include positive and negative scenarios and cover various aspects of the software, such as user interface, functionality, performance, and security. It’s also vital to prioritize test cases based on the level of impact on the overall functionality of the software, as well as the frequency of use.

At Testlio, we’ll work with you to develop comprehensive test cases that are tailored to your specific needs. By ensuring a robust set of test cases, you can be confident that your product will continue to perform well after updates.

More Resources

If you’re just getting started with learning about regression testing, you can go deeper with this selection of top resources:

Regression testing is a crucial aspect of software testing that ensures the stability and reliability of your product. By understanding the different types of regression testing, creating a robust testing strategy, and choosing the right testing approach, you can optimize your testing process and minimize the risk of releasing bugs into the market.