A Guide to Regression Testing: Types and Best Practices

A Guide to Regression Testing: Types and Best Practices

As software systems become increasingly complex when new features are added, it becomes more challenging to perform comprehensive regression testing. To overcome these challenges, developers and testers must follow established best practices and use various types of testing techniques. 

In this guide, we will explore the different types and discuss the best practices for effective and efficient testing.

What is Regression Testing?

Regression testing is a software testing process that ensures that changes or updates made to an application do not negatively impact its existing features or functionality. This process involves re-executing previously developed test cases and checking if they still pass or if any new defects have been introduced. 

The goal of regression is to detect and fix any unintended consequences of software changes, such as new bugs, errors, or performance issues.

Depending on the size and complexity of the software program, it can be done manually or automatically. Automated testing is a more efficient and effective approach, as it allows testers to execute test cases quickly and repeatedly. Overall, it is a critical process in software development that helps ensure the quality and reliability of the application.

When Should This be Performed?

Software regression testing should be performed in the following scenarios.

After Bug Fixes

Whenever a bug is fixed, it is essential to perform software regression testing to ensure that the fix did not cause any new defects or issues in the application. It helps ensure that the application works as expected and that the bug fix did not break any other parts of the software.

After New Features are Added

As new features are added to the program, regression testing should be undertaken to ensure that they do not disrupt the existing functionality of the application.

After Changes to the Environment

Changes to the operating system, hardware, or software environment can have unintended consequences on the application’s functionality. It should be carried out to make sure that the program still functions properly in the new setting. 

After Updates or Upgrades

Whenever the application is updated or upgraded, regression testing should be performed to ensure that the update did not cause any new issues in the application. This is especially important when the update involves changes to the core components of the application, such as

  1. Database Schema
  2. Libraries
  3. Frameworks

Different Types of Regression Testing

There are several types that software teams can use, depending on the nature of the changes to the software application. Some of the most popular varieties include the following.

Unit Testing

Regression testing of this kind entails testing distinct pieces of code, such as methods, classes, or functions, again after modifications have been made. Unit testing is typically performed using automated test cases and is useful for catching bugs introduced by changes to specific code units.

Partial Testing

This type of testing involves retesting a subset of the entire test suite after changes have been made to the application. Partial testing is useful when there are time or resource constraints and when the changes made to the application are small or localized.

Full Testing

Regression testing of this kind entails rerunning the complete test suite following application modifications. Full testing is the most comprehensive approach and is useful when the changes made to the application are significant or widespread.

Selective Testing

This type of testing involves selecting a subset of test cases from the entire test suite based on their importance or criticality to the application. Selective testing is useful when time and resources are limited, and the focus is on testing the most critical parts of the application.

End-to-End Testing

Regression testing of this kind involves evaluating the complete application—all of its features and functionalities after modifications have been made. End-to-end testing is useful for detecting issues that may arise from the integration of different parts of the application.

Retest-All Testing

This type of testing involves retesting all test cases, even those that have passed previously. Retest-all testing is useful when the software team wants to ensure that no new issues have been introduced into the application.

What are the Best Practices for Regression Testing?

Here are some best practices for achieving effective regression testing:

Create a Comprehensive Test Suite

The first step in achieving effective testing is to create a comprehensive test suite that covers all aspects of the application’s functionality. The test suite should include

  1. Test Cases for all Features and Functions
  2. Negative Scenarios

Automate Testing

To speed up the testing process, it’s essential to automate as much of the testing as possible. This includes

  1. Automating Test Case Execution
  2. Test Data Preparation
  3. Reporting

Automated testing tools can help reduce the time and effort required for testing and improve the accuracy and consistency of the results.

Prioritize Test Cases

Not all test cases are created equal, and some may be more critical than others. It’s essential to prioritize test cases based on their importance and the likelihood of failure. This allows teams to focus on testing the most critical parts of the application first and ensures that the most important bugs are caught early.

Use Version Control

Version control tools, such as Git, can help keep track of changes to the application’s code and test cases. This ensures that the right versions of the code and tests are used for testing and helps identify the cause of any issues that arise.

Conduct Regular Regression Testing

Regression should be performed regularly, preferably after every significant change to the application. Regular testing helps catch issues early and prevents them from accumulating and becoming more challenging to fix later on.

Collaborate and Communicate

Testing is a team effort, and it’s essential to collaborate and communicate effectively to ensure that everyone is on the same page. This includes

  1. Sharing Test Results
  2. Identifying Issues
  3. Coordinating Efforts to Fix Them


In conclusion, software regression testing is a critical part of the software development lifecycle that helps ensure that changes to an application do not introduce new bugs or issues. There are several types of it that software teams can use, including unit, partial, full, selective, end-to-end, and retest-all. Each type has its benefits and should be chosen based on the nature of the changes made to the application and the available resources. 

To achieve effective software software regression testing, it’s essential to follow best practices such as creating a comprehensive test suite, automating testing as much as possible, prioritizing test cases, using version control, conducting regular testing, and collaborating and communicating effectively. By following these best practices, software teams can catch issues early, reduce the risk of bugs and failures, and deliver high-quality software that meets users’ needs and expectations.