Software defects don’t just cause frustration—they come with a hefty price tag. According to a study by the National Institute of Standards and Technology (NIST), these issues cost the U.S. economy $59.5 billion every year. The good news? Smarter testing strategies could prevent nearly 35% of those costs.

Testing software effectively isn't just about reducing costs—it's about focusing your efforts where they will provide the most impact. This is where understanding test coverage can make a real difference.

What is Test Coverage? 

Test coverage tracks how much of your product—its features, risk areas, or code—has been evaluated during testing. The true value, however, comes from prioritizing the critical areas. By focusing on what’s most important to your business and your users, you’ll ensure your testing delivers meaningful, actionable results.

10 Things to Consider for Test Coverage

1. Critical user journeys and workflows 

Your users depend on workflows like purchasing or account setup to achieve their goals. Testing these paths thoroughly ensures smooth functionality, improves user satisfaction, and reduces service disruptions. Similarly, operationally critical processes that your business relies on should be prioritized.

When Apple Maps launched in 2012, users were frustrated by inaccurate directions, missing landmarks, and distorted satellite images. The app’s failure to support essential workflows, like navigating or finding locations, led to widespread backlash and reputational damage. This underscores the importance of prioritizing critical workflows during testing.

Actionable Advice: Map out the most common workflows your users follow and identify key points of interaction. Use test cases that replicate these scenarios, and consider running usability tests to capture any pain points users might encounter.

2. Core functional requirements and acceptance criteria

Your product’s core functionality—like processing payments or managing accounts—must work seamlessly. Validate these must-have features and ensure they align with the success metrics in your acceptance criteria. This keeps stakeholders happy and your product on track to meet its primary purpose.

Actionable Advice: Review your acceptance criteria with stakeholders to ensure it aligns with customer expectations. Then create a checklist for each functional requirement and validate these items in various environments to ensure compatibility and robustness.

3. Risk and impact

Some areas of your product carry more risk than others. Prioritize high-risk areas, such as financial transactions, sensitive data, or heavily used features, where failures could significantly harm users or your business.

The Boeing 737 MAX crisis, while an extreme case, serves as a sobering reminder of the consequences of insufficient testing in high-risk areas. For software, similar risks might exist in financial systems or core functionality, where flaws can result in reputational and financial harm.

Actionable Advice: Perform a risk assessment to categorize features based on potential impact. Assign more testing resources to features with high business impact or user risk, and simulate edge cases to understand how the product responds under pressure.

4. Code coverage and change management

Testing isn’t just about what you build; it’s also about what changes. Use code coverage to identify untested areas and focus on parts of the codebase that change frequently. Coupled with regression testing, this helps maintain stability as your product evolves.

Actionable Advice: Use tools like JaCoCo or Istanbul to monitor code coverage. Whenever a change is made, prioritize tests in areas of the codebase that are most likely to be affected, and ensure that your regression test suite runs consistently.

5. Historical data and production bugs

The past is a treasure trove of insights. Use bug trends and past production issues to guide your test coverage. Address recurring problems and known weak points to avoid repeating the same mistakes.

Actionable Advice: Maintain a detailed bug log, categorizing issues based on feature or area. Review these logs before each release cycle to determine which areas require the most thorough testing.

6. Business objectives and service-level commitments 

Tie your testing strategy to your company’s goals. Focus on revenue-generating features, improving customer satisfaction, or meeting service-level objectives (SLOs) like performance benchmarks and uptime. Your users will appreciate the difference, and so will your bottom line.

Actionable Advice: Define clear business KPIs and identify how they relate to different product features. Develop testing metrics that support these KPIs, such as average response time or customer satisfaction scores.

7. Regulatory and compliance requirements

For industries with strict regulations, compliance testing is non-negotiable. Ensure your test coverage includes standards like GDPR for privacy or FDA regulations in healthcare. Meeting these requirements protects your business from legal risks and builds user trust.

Actionable Advice: Create a checklist of all relevant compliance requirements for your industry. Regularly audit your test cases to ensure they meet these standards, and stay updated on changes to regulations.

8. System complexity

Complex systems are like puzzles—one missing piece can cause chaos. Focus on high-complexity areas to uncover hidden dependencies or unexpected interactions, ensuring your product remains stable under pressure.

Actionable Advice: Use dependency maps to visualize how different components interact. Pay special attention to integration points between modules and perform stress tests to uncover areas of vulnerability.

9. Developer feedback loops 

Faster feedback means faster fixes. Prioritize test coverage in areas where quick feedback can help developers address issues before they escalate. This keeps the development process smooth and avoids costly problems down the line.

Actionable Advice: Implement continuous integration (CI) pipelines that include automated tests. Use tools like Jenkins or GitLab to provide developers with quick results, ensuring that any new issues are flagged immediately.

10. Emerging technologies and edge cases

New technologies like AI bring exciting opportunities but also unique challenges. Test coverage should account for accuracy, unpredictable outputs, and edge-case scenarios. Whether it’s AI or another cutting-edge feature, thorough testing is key to maintaining trust and safety.

Tesla’s Autopilot system has struggled with edge cases, such as misinterpreting the side of a truck as the sky or failing to detect stopped emergency vehicles. These issues emphasize the importance of testing for edge cases in emerging technologies, where unpredictable behavior can jeopardize trust and safety.

Actionable Advice: Set up specific test cases for edge scenarios—like rare user inputs or unexpected system states. When working with AI, use training data that includes a wide variety of real-world scenarios to minimize unpredictable outcomes.

Wrapping Up 

Effective test coverage isn’t just a number—it’s a strategy for aligning your testing efforts with what truly matters to your users and your business. By focusing on critical workflows, addressing high-risk areas, and connecting your work to tangible business goals, testing becomes a vital part of delivering a high-quality product.

Think of test coverage as a decision-making tool. Instead of aiming for blanket coverage, prioritize testing where it delivers the most value and mitigates the biggest risks. Strategic test coverage reduces surprises, boosts user confidence, and creates a strong foundation for long-term product success. By focusing on high-impact areas, you save resources while delivering an experience that meets user needs and holds up in the real world.

Hit the button below to hear Alex Larsen discuss how beta testing results can enhance future quality testing.