In my 12+ years as a test automation architect and lead, I’ve helped various teams achieve 2x testing efficiency and velocity through optimal test coverage.
Having learned the ropes across manual testing, test management, automation framework design and lab administration has given me a 360 degree perspective.
In this playbook, I’ll distill battle-tested tips to help you maximize test coverage for your web and mobile apps.
I aim to provide actionable guidance on strategically improving unit, integration, UI and platform coverage. Follow along as we level up your testing game together!
First Up: What is Test Coverage and Why Care About It?
Test coverage tells you what portions of your app codebase and functionality have been evaluated by tests. It offers a quantifiable measure for test completeness.
Typically coverage is tracked for:
- Unit tests – Exercise isolated code units
- Integration tests – Validate component interactions
- Overall code coverage – Lines, branches touched by tests
- UI tests – Test interface flows and UX
Higher coverage directly translates to fewer production defects and happier users.
As an example, Facebook sees 50% fewer defects after increasing test coverage by 20%. Industry research suggests each coverage point above 80% reduces app issues by 16%.
Key Benefits of High Test Coverage
Driving higher test coverage offers 3 key business benefits:
- Reduced product defects – With more testing, you catch more bugs early
- Lower cost – Fixing bugs pre-launch is 50x cheaper
- Faster delivery – Confident releases with lower risk
Let‘s look at proven ways to improve coverage at both code and system levels.
Boost Unit and Integration Test Coverage
Unit and integration testing ensures base code units work as expected and combine correctly. This builds a resilient code foundation.
Here are 5 key strategies I recommend for increasing unit and integration coverage:
1. Enable Developers to View Their Code Coverage in IDEs
Embed code coverage plugins within IDEs like IntelliJ, Eclipse and Visual Studio to make it invisible for developers. This helps them view coverage in real-time as they code without any friction.
Popular plugins like Jacoco and Cobertura visualize block-by-block coverage in editor windows. Configure coverage thresholds to flag low covered blocks.
2. Set Gradual Coverage Improvement Targets
Start with a pragmatic coverage goal like 60% for unit tests and integration tests each. Gradually increase target by 15-20% each release. Celebrate meeting goals and review gaps transparently as a team.
Balance coverage needs with release priorities and technical debt. Go overwhelming developers upfront.
3. Lead by Example with Golden Path First
Guide teams to cover happy path functionality thoroughly before accounting for all edge cases. Exercising critical business logic offers best ROI on effort.
Seed key integrations like login, payments early. Progressively expand testing to secondary code paths. Highlight good test patterns for others to emulate.
4. Augment with Automated Generators
Supplement developer-written tests with auto-generated test cases for expanded coverage.
Smart generators like Evomaster analyze code paths and create unit tests to cover untouched areas. This helps reveal overlooked scenarios.
Review auto-generated tests before integrating them for readability. Generators complement but don‘t replace manual tests.
5. Enable Testability in Code Reviews
Add testability as a checklist item for peer code reviews. Scan for dependencies that impede testing like hard-coded data, static methods etc. Refactor code with test interfaces upfront.
Encourage teams to view testability as an important aspect of well-written code, not an afterthought.
Now let‘s look at improving overall system test coverage.
Expand User Interface Test Coverage
While foundational unit and integration testing is key, you need end-to-end UI testing to validate actual system behavior.
User flows change often so rigorous UI testing is critical for business success. Here are proven ways to scale UI test coverage:
1. Define Target Device-OS-Browser Matrix
Outline target combinations you want to test against based on real user traffic. Frame clear UI coverage goals against this matrix.
Cover popular iOS, Android variants and OS versions plus Edge, Chrome and Firefox browsers. Confirm accessibility testing needs upfront.
2. Prioritize Core User Journeys
Not all test cases bring equal value. I recommend focusing on primary conversions first – signup, purchase, media playback etc. Define target coverage for critical pathways.
Rigorously validate 10 vital user journeys end-to-end before accounting for complex edge flows. Guide users here to catch material defects faster.
3. Combine Automated API Layer Tests with UI Tests
Leverage test automation across API and UI layers for reliable end-to-end testing. For example:
- Utilize Postman for API test automation
- Use Selenium with browsers for web UI testing
- On mobile, leverage Appium and Espresso
Ground-up coverage across layers catches more slip-through defects early. Automate the critical happy paths first.
4. Monitor Coverage with Reporting Dashboards
Visually track UI test progress against defined user journeys with coverage scorecards. Flag areas needing focus.
Celebrate testing milestones and wins with teams regularly. Reports keep everyone aligned on gaps.
5. Validate on Real Devices using Cloud
While simulators have improved, subtle rendering and UX issues still emerge on real devices. Testing locally at scale is very complex.
Leverage real device cloud solutions like BrowserStack that provide instant access to 3000+ real mobile and desktop environments. Run automation suites in parallel against the entire matrix.
The cloud model offers the best ROI on effort here for end-to-end validation.
Pro Tips to Further Boost Your Coverage
Beyond core test automation and coverage tracking practices, here are some pro tips I recommend:
Analyze Usage Patterns Frequently
Continuously evaluate your device matrix and test priorities based on real user data. This ensures alignment with rapidly evolving user needs.
Actively Involve Developers in Reviews
Collaborate with devs early on test planning and environment management. Joint ownership of quality drives up coverage.
Mitigate Test Flakiness Proactively
Act quickly on flaky test failures by quarantining and not disabling them. Analyze root causes – test data gaps, environment issues, timeouts etc. Systematically reduce flakes over time through automation hygiene.
Validate Accessibility Thoroughly
Reserve time and bandwidth for rigorous accessibility testing across devices and helpers. Discover gaps proactively vs. reactive audits.
I hope these proven tips help you drive step-function improvements in test coverage, quality and velocity. Share your experiences and feedback as you level up coverage for your apps!
