Regression Test Plans and Functional Test Plans Are Not the Same

Functional test plans and regression test plans serve distinct purposes and should not be confused. However, in the fast-paced Agile, DevOps, and CI/CD environments, functional test suites are often mistakenly used as regression test plans. This approach is costly and ineffective. While there can be overlap between the two, they should be viewed as separate components within a well-structured testing strategy.

Functional Testing: The primary goal of functional testing is to ensure that new requirements are met. This involves thorough requirements gathering, careful test planning, and meticulous test execution. Every detail of the new functionality must be validated, including elements on the page, business rules, calculations, user roles, and error messages. Functional testing is typically best suited for manual testers, as these tests usually do not need to be repeated multiple times. Although a functional test plan might be repeated a few times, automating it through scripting tools like Selenium is generally not cost-effective. The return on investment (ROI) is rarely met, and the maintenance costs of such a test suite are prohibitively high.

Regression Testing: In contrast, regression testing ensures that existing functionality continues to work as intended after new changes are introduced to the system. In an Agile world where CI/CD and DevOps practices lead to frequent deployments, regression testing must be executable within hours, if not minutes. This demands a carefully designed test strategy that emphasizes automation. Nearly every aspect of regression testing should be automated, and the regression test plan needs to be carefully crafted with input from all stakeholders.

An effective regression test plan should include:

• Unit tests at the method, function, class, and API levels
• Backend data testing to validate business rules engines, calculations, and data commits
• Automated scripts for a subset of functional tests that offer the highest ROI and maximum system coverage
• An execution and maintenance plan

Creating an effective regression test plan requires strategic leadership and deep technical knowledge to ensure comprehensive and effective test coverage. Stakeholder collaboration is crucial: developers, business analysts, and testers must all agree on the plan and contribute to developing and maintaining the test suites. Regression tests should be integrated into a DevOps pipeline, with a reporting system that allows all stakeholders to view test results and trends.

Overlap and Integration: While functional and regression tests have different primary objectives, there can and should be some overlap. Certain automated functional tests, particularly those validating critical paths or high-risk areas, can be incorporated into the regression test suite. This ensures that these important functionalities are consistently validated with every deployment, without the need for separate, redundant testing efforts. Moreover, a well-designed regression test plan can make some functional tests redundant, as these system requirements would be covered adequately by the regression suite. Therefore, developing regression and functional test plans concurrently is beneficial to ensure complementary and efficient testing efforts.

Conclusion: Functional testing and regression testing serve different purposes, but they are not mutually exclusive. While automating functional test suites should not replace the regression test plan, thoughtful overlap between the two can optimize your testing strategy. This ensures both new features and existing functionality are thoroughly validated with minimal redundancy and maximum efficiency