Software Regression Testing: Value in Iterative Development

Today, software regression testing is an indispensable practice and a critical process. More so, regression testing alongside version control and automation are the staples of modern-day iterative development. While all those things make perfect sense for any engineer, the business-level interpretation might not be as straightforward and is fraught with misconceptions. For instance:

• iterative development might sound like an expensive experiment; 
• version control and meetings to discuss the branching strategy may as well be unnecessary overhead;
• Regression testing is likely to be associated with double-charging for an already shipped and handed off functionality;
• Automation might come across as a luxury item for a mature business.

In reality, though, all of this ensures business velocity, reliability, customer trust, and revenue. 

• Iterative development equates to high market agility. It is the tool to quickly adjust your strategies, add features, or tweak campaigns to either capitalize on opportunities or produce a quick response to a potential threat or a competitor’s move. 
• Version control is the necessary care about the Business Asset. It prevents loss for the business and serves as an audit trail. It reduces the ‘investigation’ and resolution time manyfold.
• Software regression testing is a safety net that preserves the app’s capability to generate revenue while mitigating potential losses. 
• Finally, automation is a powerful cost-saving measure. Why pay $50 or $80 an hour for an engineer to manually check for errors, while a script can do it for 5 cents and in 5 seconds? Plus, testing can be quite a repeatable activity, and humans are mistake-prone, whereas machines aren’t. 

In this blog post, we’ll break down the business value of software regression testing and why it is particularly important in this fast-paced market environment requiring iterative development. 

The ROI of Quality: Hard Data on Costs of Bugs in Production

Moving on from debunking the misconceptions, the need for regression testing is well-justified by the potential cost of debugging in production. The white paper by NIST and IBM engineers shows that:

what might cost only minutes or hours to fix in the design stage will cost 30 times that in production.

Another report calculated that debugging costs  620 million engineering hours and 61 billion dollars annually. To counter that, 88% of companies introduced CI/CD practices, where automated software regression testing plays a central role. 

Atlassian further calculated that the cost of downtime is between $5,600 to $9,000 per MINUTE in 2016 prices. Surely, these ranges refer to the mature organizations, not startups looking for their product-market fit. Yet, these potential risks justify the need for investing in automation of regression testing. Moreover, the earlier you cast the safety net, the more money the company will save both on development hours for debugging and revenue losses due to software failure. 

Finally, while for a first-time entrepreneur, iterative development might sound like a novelty, consider that 35% of organizations ship changes or updates HOURLY. Therefore, when such a frequent change to the product occurs, automated software regression testing is the only optimal solution to prevent bugs in production and possible issues that follow. Which is why even in MVP development, professional Startup Services start building automation suites early, as soon as it makes practical sense. 

What is a Software Regression Testing Plan?

A regression testing plan details the approach to testing that the new functionality, bug fix, or update will not break the existing functionality. In other words, software regression testing ensures that today’s progress does not disrupt prior progress. 

For instance, imagine adding tagging functionality for posts. That definitely alters how they are loaded from the databases. Surely, a developer does unit tests and the bit they commit is perfectly functional. However, this change might have broken the homepage feed, which this developer hasn’t been responsible for. Or, pagination could have started misbehaving, which was also outside the scope of the ticket the developer worked on. This is what software regression testing covers, and the more people work on the codebase, the more critical it gets.

Purpose and Scope of a Regression Test Plan

The business purpose of the regression testing plan is to achieve a certain percentage of production build stability (for example, expressed as desired uptime) and ensure a particular delivery speed (hourly, weekly, etc.) while respecting the budget. Budget for testing often varies between 10% (lean MVP development) and as much as 50% (high-stakes industries like healthcare, fintech, IoT, etc) of the development budget. 

From an engineering standpoint, the purpose of a software regression testing plan is to develop and maintain a sequence of actions that ensures the existing codebase remains bug-free after new commits. Ideally, tests should cover as much of the codebase as possible and strive for self-testing mode. According to Martin Fowler, a renowned software developer:

“Self-Testing Code is the practice of writing comprehensive automated tests in conjunction with the functional software. When done well, this allows you to invoke a single command that executes the tests – and you are confident that these tests will illuminate any bugs hiding in your code… As a pillar of Continuous Integration, it is also a necessary part of Continuous Delivery.”

The scope of the software regression testing plan varies depending on whether it is an MVP-stage startup, post-PMF (product-market fit), or a mature product at scale. For an MVP product, code can be discarded fast, and new features can be added even faster. Therefore, writing automated tests for every new feature can be a waste, and manual testing prevails. For a mature product, there is likely to be a dedicated software regression testing suite triggered through CI/CD pipelines automatically. However, this suite of automated tests appears over time, and even at the MVP stage, it is sensible to automate certain checks.  

Regression Testing for Iterative Development: MVPs

So, for an MVP product, the main currency is the speed of delivery to market. If a new core feature breaks a non-core element, but saves development hours and costs, it is worth the risk.  After all, MVP products intentionally reach a limited audience, who are often early adopters. They generally tolerate imperfections, and ultimately, a team might completely replace a non-core element within a couple of weeks or months. 

So, for an MVP software testing plan, the purpose is to ensure that new features do not break the core flow that demonstrates product value and makes users happy. As such, the scope is restricted to ensuring new changes do not break features of a single core user flow. 

Regression Testing for Iterative Development: At Scale

In case the product is more mature, released to wider audiences, or belongs to regulated niches, the scope of regression testing would be considerably different. As such, business considerations include user trust, preserving revenue flows, and compliance with regulations.

• If a user pays for a certain feature that gets broken upon release, the refunds and customer support queries are likely to skyrocket. 
• Some customers might post on social media about bugs and negative experiences. This is damage to trust and reputation. 
• If anything happens with authentication flows or data operations and there is a leak or exploitable vulnerability, lawsuits might follow. 

In these cases, a software regression testing plan has a much more substantial business value. However, since it is impossible to test for everything, such companies employ different test prioritization techniques to limit the scope. They are:

• Prioritization based on coverage metrics (data-informed approach);
• Dynamic and static testing (often combined for the best results);
• Ranking methods (based on developer expertise and bug history of the app);
• Combinatorial testing (efficient, produces real cost savings, and high ROI);
• Neural test case prioritization algorithms (still a bit experimental with unclear ROI). 

Overall, software testing in MVP development should be treated as a living and evolving document reflecting the product stage and business goals rather than being a mere QA templated checklist to follow blindly. 

Key Components of a Regression Testing Plan

A software regression testing plan may take different forms. However, it often includes the following components:

• Release Version
• Purpose / Objectives
• Scope
• Environment Variations 
• Risks and Mitigation Policies 
• Regression Testing Deliverables

The plan can have more sections than that, depending on the team and the company’s needs. For instance, high-stakes businesses often include expanded risk sections and system descriptors. Others choose to detail roles and the allocated testing hours, and so on. We’ll break down the sections that make sense for every regression testing plan.

Release Version

Same as the code, the accompanying test cases change or evolve. While QA engineers also give unique identifiers to test plans, non-engineer roles often use these documents based on versions. Versions themselves correspond to either product milestones, major feature releases, or incidents. This allows stakeholders to know what team tested exactly at that particular point, why, and under what conditions. 

For instance, a seller on a marketplace needed to issue a refund in EUR, but it failed. This seller contacts the support and reports it. While support contacts the development team, the support lead is also likely to pose a question, “Did we test this scenario before?” and pull up the corresponding testing plan to investigate. 

Purpose / Objectives

The purpose of software regression testing in MVP development is to ensure that tests catch all unintended side effects or software defects. If it is an early-stage startup with limited QA resources, this section outlines quality standards to maintain between releases. For regulated startups, it would also include compliance requirements, especially pertaining to security, data integrity, and privacy. 

Scope

In practice, regression testing often utilizes both static and dynamic approaches. The static approach implies a certain number of tests that run automatically regardless of what has changed. In contrast, the dynamic approach is selective of what areas the change is likely to impact.

Baseline static checks often include critical areas based on operational and business perspectives. They include authentication, API endpoints, payment logic, and such. Overall, things that should not break ever.

Dynamic checks appear depending on the change itself. For instance, let’s imagine a release of updated tax logic. The developer checks and everything works. Then, the regression testing plan verifies whether overall billing logic still works correctly, from applying discounts and promo codes to calculating totals and invoice generation.

Environment Variations

Generally, when developers commit a change, everything works well in their development environment. However, the production environment and the users’ environment might yield different outcomes. This section specifies variables of those environments for testing purposes.

For instance, the new release changes the file upload logic. As a result, on slow networks, there is a timeout issue or a failed upload. Another example is adding a UI element. And, as a result, on small mobile screens, another button disappears or the layout breaks. There are regression issues on slow networks and small screens. 

Risks and Mitigation Policies

This section of a software regression testing plan should establish actions to take:

• If a regression test discovers a problem;
• If bugs appear in production when all tests have been passed.

In the first case, depending on business priorities, the responses can be as follows:

• Block the release.
• Proceed with release, but temporarily disable the feature.
• Issue a hotfix.

The business priorities and operational criticality determine which action should be taken. 

The second thing is mitigation policies. Development often faces tight deadlines, limited resources, and evolving requirements. Therefore, tests often ensure complete codebase coverage. In addition, when it comes to modern development and especially AI integrations, testing of complex dependencies might be limited or time-consuming. As such, it should be accepted that certain bugs can still make it into production. 

In this case, mitigation policies specify monitoring procedures, team responses depending on bug severity, and patch release to restore operations. Basically, from the business perspective, this ensures that even if something unpredictable happens, the team responds predictably.

Regression Testing Deliverables

This section lists the documentation and logs generated during the software regression testing. In iterative development, the goal of this documentation is practical value. For instance, there is no need for lengthy reports when a simple alert will do. Also, logs need to be formatted and grouped so that it is easier to identify recurring issues and enhance build stability. 

Summary

Iterative development relies on software regression testing alongside version control and automation. From a business perspective, the ROI of quality can be measured in thousands of dollars lost per minute of downtime. Therefore, investment in regression testing is justified starting with the MVP stage.

The purpose and scope of a software testing plan evolve depending on the product stage and also the product’s nature. High-stakes and mature companies like healthcare would require substantially more testing effort. In contrast, early-stage MVP products are likely to opt for manual testing and automate testing for only the critical user value flow. 

While testing plan components can vary, universal ones are testing plan version, purpose/objectives, scope, environment variations, risk and mitigation policies, and deliverables.

FAQ: Software Regression Testing: Value in Iterative Development