Testing often gets overlooked as applications race to launch features. But nothing damages an app faster than crashes or bugs interrupting users. As an app testing specialist with over 15 years optimizing enterprise platforms handling millions of users, I’ve developed an expertise arsenal of testing strategies to deliver a seamless experience across every device and browser.
This comprehensive guide will overview the purpose, process, tools, and best practices for 16 essential testing types modern apps require. Follow these app testing commandments, and you’ll minimize defects while maximizing happy users and five star reviews.
The High Cost of Bugs
Let’s first examine the measurable impact application errors have on user retention and loyalty. Studies by Researchscape found:
- 96% of users report performance issues as primary reason for switching apps
- 25% will delete or switch apps after just one bad experience
- 60% said quality and reliability were more important than features
For context, Segment found minor UI bugs increased checkout abandonment 50%. So every visual irregularity or performance hiccup chips away at your active user base.
But comprehensive testing takes time and resources. What yields the best ROI? Prioritize test types strategically based on your app goals and metrics.
The App Testing Landscape
As this landscape shows, testing types fall into five buckets:
Performance: Load, stress, and speed metrics
UI/UX: Visual and accessibiltiy validation
Web Services: API and integration testing
Security: Vulnerabilities and compliance
Monitoring: Real-user session tracking
Now let’s overview the purpose and best practices for each testing variety in detail.
Performance Testing
Performance testing ensures speed, stability and scalability holding up even under heavy usage loads.
1. Load Testing
Load testing tools simulate concurrent users to validate maximum capacity levels before slowdowns. Using cloud services like AWS, you can subject your app servers to enormous loads.
Monitor resource metrics like RAM, CPU, network traffic, and database connections to find bottlenecks causing degradation. This reveals infrastructure weak points needing expansion to maintain speed as your user base grows.
I recommend load tests escalating at least 30% beyond your expected 12 month peak traffic. Exceeding scale limits in staging prevents post-launch crises from viral user spikes crashing apps.
2. Stress Testing
While load testing focuses on size limits before performance drops, stress testing identifies the breaking point where apps actually crash under extreme conditions.
Think unlikely scenarios like running complex reports while also saving huge data uploads during peak user volumes already near capacity. Discovery disasters before they strike end customers.
I advise a “chaos engineering” approach to destabilize systems in staging using random injects like excessive background processes, expired certificates, unavailable databases, and throttled server CPU/memory. Map the sequence of dominoes falling down for preventative alerts.
3. Page Speed Testing
With 53% of mobile site visits abandoned if pages take over 3 seconds to load, speed is a competitive advantage.
Profile complete user journeys through your app, timing page rendering, scripts execution, and resource downloads. Waterfalls reveal heavy assets delaying interactivity. Optimize images, defer JavaScript, and reduce server response latency.
Generally target page loads under 2 seconds over 3G networks for native feeling performance.
UI and UX Testing
Vigorously testing UI rendering and UX flows across varying screen sizes prevents disjointed experiences fragmenting your user base.
4. Responsive Testing
With a proliferation of phone, tablet, laptop, and even foldable display sizes today, responsive web design dynamically adapting layouts is crucial. Misaligned elements from testing only on latest iPhone models leads your app to appear broken on other devices.
Responsive testing validates style cascades, element arranging, image sizing, and text wrapping displaying elegantly across viewports. Flag any gaps with a bed of device sizes:
- Phone: 5-inch to 6.5-inch displays
- Tablet: 7-inch, 9-inch, 12-inch
- Laptop: 13-inch, 15-inch
- Desktop: 24-inch monitor, 4K resolution TV
Fine tune breakpoints until pixel perfect parity across this matrix.
5. Visual Regression Testing
User interfaces constantly evolve. Even tiny CSS adjustments might accidentally skew modal alignments, invert icon colors, or wrap text formatting. Such visual defects appear obviously disruptive when pointed out, yet slip unnoticed without vigilant testing.
Visual regression testing compares UI screenshots after each code change to detect pixel deviations from baselines. Applitools, Percy, Wraith and PhantomCSS are excellent for catching these rendering errors across browsers and devices.
Integrate visual monitoring into build pipelines, or schedule batch analysis like daily automated baseline comparisons. The quicker you detect discrepancies, the quicker fixes reach users without damaging experiences.
6. Accessibility Testing
With 25% of users possessing some disability reliance on screen readers, color blind modes, captioning, and keyboard navigation, accessibility testing ensures your app’s interface remains equally usable and consumable to people of all capacities.
Audit across categories like screen reader pronunciation, color contrast ratios, form field labeling, focus indicators, and landmark elements. Grade against standards like WCAG 2.1 providing analysis and code improvement guidance. Remediate errors ahead of receiving complaints or legal action over lacking accommodations.
7. Bug Reproduction Rate
After discovering an error, gauge reliability of reproduction by testing duplication frequency across environments and devices.
- If reproducing over 80% of the time, prioritize rapid fixes for high impact user experience risks.
- Between 20-50% reproducibility signals complex dependency issues deserving engineering investigation.
- Under 20% likelihood points to edge case flaws addressed in a future iteration.
Precisely monitoring reproduction rates prevents overreacting while also avoiding negligence of serious defects eroding application stability.
Web Service Testing
With few apps operating as isolated islands, testing interoperability with external APIs and web services verifies critical integrations handle actually handle real world scenarios.
8. API Testing
Whether tapping payment processors, weather data, or shipping rate calculators, rigorously test API inputs and outputs against documentation to validate seamless syncing.
Scrutinize status codes, enforce schema expectations, authenticate improperly, probe for unhandled errors. What happens when services go offline? Can your app handle malformed responses when upstream data gets corrupted? Devise edge cases likely to break integrations.
Postman provides an excellent API testing ecosystem spanning validation libraries, mocking servers, and test automation.
9. Security and Compliance Testing
With regulatons like GDPR imposing heavy fines for violations, certify your app handles sensitive PII like emails, locations, and biometrics safely with compliance testing.
Audit data flows against standards like ISO 27001 with permeation testing injecting PII throughout infrastructure to flag unsafe transmission channels or vulnerable storage locations putting private data risk.
Security Testing
Hackers exploit the slightest security loopholes, making bulletproofing apps through ruthless penetration testing imperative.
10. Static Application Security Testing (SAST)
SAST deeply scans application source code for weaknesses like SQL injections, cross-site scripting flaws, insecure encryption algorithms, buffer overflow risks, and improper authentication logic before releases expose these bugs as liabilities.
Integrate SAST packages like Checkmarx, Veracode or Synopsys into your SDLC, scanning during development, QA, and pre-production. Address high probability and critical severity issues immediately, while incrementally improving moderate risks in subsequent sprints.
11. Dynamic Application Security Testing (DAST)
Unlike SAST evaluating static code, DAST tests running apps like an actual attacker probing for holes. It manipulates interfaces, stalks data flows end-to-end, and attempts common exploits like cross-site request forgery or breaking out of sandboxes.
A hybrid approach combining SAST code analysis with DAST live penetration testing builds security depth protecting your application’s attack surfaces inside and out.
12. Open Source Analysis (OSA)
With over 70% of apps built using open source libraries and components, keeping dependencies updated is essential for blocking newly discovered vulnerabilities from exposure.
Continuously scan build manifests against databases tracking open source bugs and license risks. Automate reporting on outdated packages in need of upgrades to avoid becoming victim to published exploits you should have patched.
Real User Monitoring
Once an app hits production serving actual customers at scale, issues emerge even the rigor of testing could not predict. Proactive monitoring provides observability into errors and degradations negatively impacting user experiences.
13. Crash and Error Reporting
Unexpected shutdowns and untrapped exceptions frustrate users,yet prove difficult to reproduce manually. Real-time crash listeners and error handlers like Sentry capture source stack traces and environment context needed to pinpoint why fails occur.
Funnel events into aggregation dashboards spotlighting severity levels, affected devices, error frequency, and operational analytics to guide engineering priorities for high impact fixes that transform app stability.
14. Session Replay
Record and play back random individual user journeys through your live app to understand precisely how customers navigate flows. Detected usability struggles like repetitive actions or abandonments direct UX enhancements increasing conversions and satisfaction.
15. Log Analysis
Machine generated log datasets provide rich forensic goldmines for identifying issues missed by monitoring alone. Analyze traffic volumes, trend performance metrics over time, and graph anomaly spikes indicating emerging platform faults.
16. Real User Performance
Synthetics effectively emulate user journeys through monitoring checks. But subtle application intricacies unique to native browsers and devices can still be misrepresented.
Real user experience testing installed on client devices provides definitive app speed and quality insight directly from your genuine audience base exceeding synthetic imitation. Benchmark standards properly represent genuine mobile use conditions.
Balance Automation With Exploratory Testing
While test automation accelerates validation velocities, adaptable human perception discern nuances in visuals, content, and flows that rigid scripts overlook. Strike a balance utilizing automation for repetitive sanity checks while allocating days dedicated exclusively to manual real user testing exposure.
Exploratory testers also better judge subjective satisfaction with UX and UI designs over pure functional testing. Listen to qualitative feedback, not just quantitative benchmarks.
Launch With Confidence
Equipped with this comprehensive quality assurance arsenal, thrust apps into the wild knowing performance, security and reliability measure up even under rapidly escalating demands. Building a smooth user experience drives organic growth and satisfaction much more than features alone ever could. Place testing on equal ground as development, and thrive forevermore.
