Automated Regression Testing Basics

Automated Regression Testing Basics

All products need updates and new features to stay usable and safe for users. And even if your code works seamlessly after some modification, bugs and failures can happen. To ensure that recent code changes don't lead to errors, the development team carries out regression testing. 

Regression testing is a functional type of testing with a primary goal to ensure that new code changes, updates don't cause failures and don't affect code overall. 

The core principle of effective regression testing is repetitiveness. Thus, regression testing is an integral part of an Agile framework that is characterized by frequent deployments. Developers introduce a new build within short sprints. And dev teams must ensure that changes don't cause failures after every build. So, regression testing is executed often to prevent failures and maximize effectiveness. 

Regression testing is often confused with retesting, whereas they are different kinds of testing. The main difference between regression testing and retesting is that retesting focuses on specific issues while regression testing cheks code overall. Retesting ensures that failed test cases work properly after eliminating failures. Developers know what causes bugs and fix them, and after that engineers, execute retesting to ensure that bugs don't emerge again.   

Repetitive and big data test cases are the best candidates for automation. But automation is expensive and unnecessary for small and short-term projects with small codebases. Sometimes automation regression testing is impossible due to the low ROI of it. In this case, manual testing is the best choice for regression testing. 

So the first lesson of automation regression testing is automation isn't a panacea for regression. Be selective and business-oriented for it. Besides, to make automation testing more effective, you should provide it after conducting manual regression tests. Automation regression testing should be based on manual test cases that repeatedly reveal failures.

Automation testing is extremely useful for big and mid-sized projects with increasing codebases. 

Despite the effectiveness of automation testing, it has many pitfalls and can be improved by two approaches: data-driven and keyword-driven approaches.

• The data-driven approach allows engineers to create one automation test case for multiply test data. Test cases and test data keep separately and independently of each other. A script reads data from a file and executes test cases without the need to create a new script for every set of data.  
• The keyword-driven approach engineers create action keywords for imitating users' actions in test cases. This approach has a high level of reusability too, as existing keywords can be used to multiply test cases. 

Common automation tools aren't enough for automation regression testing as it needs more features.  

Some criteria to choose the right tool for your project:

• Easy test creating. Creating scripts for automation is a hard deal that requires knowing a programming language. Scriptless tools allow engineers to create automation test cases without coding. 
• Easy rollback to the previous build version. It useful if new updates caused critical code problems. 
• Maintain prioritize regression test cast feature. After changing the code, you need to check particular parts of it first of all. Prioritize test cases allows you to control testing in the order you require. 
• Detailed reporting. Tool for regression testing should include information about previous testings, screenshots, and diagnostic information to be able to evaluate test coverage and analyze the most vulnerable spots in code.
• Reusability. Regression testing requires running a lot of test cases. The tool should have the possibility to modularize your tests. To facilitate the creation of new tests, tools should maintain a library of scripts or reusable test snippets.

The right choice of test cases for automated regression testing has great importance for relevant results. For effective results, scripts should cover manual test cases that stably reveal failures and bugs.

There are some factors to pay attention to when choosing a set of regression test cases:

• test cases that frequently led to failures
• the main functionality of the product can be damaged by recent updates
• focus on modifying functions as they can cause bugs
• include a mix of positive and negative test cases 
• check whether selected test cases covet the overall codebase

Regression testing is an essential part of Agile projects. Automation testing can facilitate arduous and complex engineers' work. But automation requires large investments, knowledge, and experience. Before choosing automation for your project you should evaluate the level of team experience, design strategy, and deep analysis of the situation.