A strategic approach to regression tests

Regression testing is a must for maintaining continuous quality in software development. It ensures that new changes don't break existing functionality, safeguarding the product.

The approach to defining and running regression tests is critical. The wrong strategy could mean missed coverage leading to high-severity defects, long testing cycles that delay software delivery or releases, and a lack of transparency around a Quality Engineer's work.

This post presents a practical approach to structuring and prioritizing your test cases for efficient and effective regression testing. The ideas are simple:

Document your test cases
Categorize and prioritize your tests
Create a regression test suite
Define a set of smoke tests
Execute the right regression tests at the right times
Follow a test case management process

Document All Test Cases - Focus on Regression

While documenting all your test cases is valuable, defining which tests will form your regression suite is even more important. These should include test cases covering your application's most critical, frequently used, and high-risk areas.

Regardless, always document your test cases as you deliver software. If you haven't documented anything yet, there is no better time to start than now! Ideally, you're working in Agile Scrum or Kanban and documenting your test cases as you work on each story. The rest of the steps will be difficult until all test cases are documented and in one place (like Jira).

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Remember, test cases should not be the product requirements source of truth during software delivery. They're merely a reference.

Categorize Your Test Cases

To manage test cases effectively, categorize them based on features or functionality. For instance, you can use categories like "Login/Registration," "Payments," or "Data Visualization." This structure not only simplifies test management but also helps identify areas that require more attention. In short, this is how you can determine coverage.

Prioritize Based on Importance and Risk

Not all test cases are created equal. Prioritize them by considering:

Importance to the product or user: What are the most critical features for users?
Risk level: Which parts of the application are most likely to fail or cause significant issues if they do?

This prioritization ensures that you focus your efforts where they matter most.

Build Your Regression Test Suite

Create a regression test suite from your prioritized test cases, factoring coverage for all categories you defined earlier. This forms the basis of the mandatory test cases that must be run regularly to ensure quality.

One strategy for choosing test cases is to select a larger number of tests from the highest priority areas and a smaller number from lower priority ones.

Identify Smoke Tests

Within your regression suite, identify a subset of smoke tests. These highest-priority tests cover essential functionality and should be quick to run. They act as an early warning system, helping you catch critical issues before they spiral into more significant problems.

Use a mechanism to tag the smoke tests, like labels, for easy querying and identification.

Automate for Maximum ROI

A critical benefit of defining a regression test suite is that it acts as our backlog for automation! Regression tests provide the highest return on investment (ROI) when automated. Since they're run repeatedly, automating them saves time and money in the long run.

Note that you may not be able to automate all the regression tests easily. For example, you may have flows or third-party integrations that require manual intervention.

Assess each test case and determine how easy it is to automate, then tag it as an automation candidate. These "automation candidate" tests can now be added to stories in the backlog and automated. A story can have 1 test case or multiple test cases associated with it (as long as they're part of the same flow).

Smoke tests should be run more regularly. A basic approach is to trigger automated smoke tests after each deployment to an environment and to trigger a complete regression automated run on a nightly or morning basis.

Follow a Test Case Management Process

Once you have a regression test suite and an automation suite, it is essential to create and follow a test case management process.

One approach is throughout a sprint, as you create and document your test cases, assess whether any of them should be part of regression. If so, add them to the suite with the appropriate tags (smoke and/or automation candidates).

Ideally, you're automating the happy paths or smoke tests during the same sprint, but if not, make sure to create an automation story in the backlog. Speaking of which, refine the automation stories in the backlog and bring them into sprints during sprint planning.

Final Thoughts

A well-defined regression testing strategy is a cornerstone of continuous quality. By categorizing, prioritizing, and automating your test cases, you ensure you're always one step ahead of potential issues. Remember, the goal is not just to test but to test smarter—investing time and resources where they will have the most significant impact.