Testing on Emulators vs Simulators vs Real Devices: An Expert Comparison

As a seasoned quality assurance expert with over a decade of experience testing mobile and web apps on thousands of different real iOS, Android, and Windows devices and models, I often get asked – should I use a real phone, an emulator, or a simulator for testing my app or website?

It‘s an excellent question, because the type test device used affects everything from your budget, to your development speed, to the comprehensiveness of your testing. The quick answer is that ideally your test methodology should leverage a combination of real devices and virtual device emulator/simulator solutions.

However, what exactly is the difference between the three? What are the pros and cons of phones, emulators, and simulators for testing? When should you use each? In this in-depth guide, I’ll share my insider knowledge to help you optimize your test stack.

The Mobile Device Fragmentation Challenge

The wide device fragmentation across mobile makes adequate testing incredibly challenging. Consider these staggering statistics:

• Over 20,000 distinct Android device models in active use
• 5,000+ variants for iOS devices
• 9 major versions of Android still with significant market share
• Similar fragmentation across languages, networks, carriers

Such diversity causes huge issues both for developers building apps, as well as quality analysts testing them. An app running perfectly on one device may exhibit serious defects on another model. Accurately simulating usage across all environments is just not feasible with physical phones.

This led to the rise of emulator and simulator tools that recreate the experience of certain devices virtually on the tester’s computer itself. Well-designed emulators and simulators can act as a force multiplier for testing teams by enabling rapid validation across far more devices than would be possible manually.

However, despite improvements, virtual testing solutions still differ greatly from real devices in many regards. Let compare them in greater detail.

Comparing Real Devices, Emulators and Simulators

Here is an in-depth feature comparison across key testing device types – real phones/tablets, emulators, and simulators:

Let‘s analyze some of these parameters in greater detail:

Speed and Performance

Emulators introduce slowdowns of 2x to 5x on average compared to native hardware performance. This is caused by binary translation overhead and inaccurate hardware emulation. Simulators and real devices have very comparable test execution speeds.

Accuracy and Reliability

In one extensive study, testing the same 10 apps across Samsung Galaxy S9 phones, the Android emulator, and real Galaxy S9 devices accessed in the cloud, 2x more unique bugs were found using real phones compared to emulators. Real devices are fundamentally more reliable for identifying issues.

Feature Support

Testing device sensor capabilities like GPS, Bluetooth etc. is still very limited on emulators whereas real phones fully support utilizing all native hardware capabilities.

This is why real devices are absolutely necessary for validating integrations, performance testing, etc. even if emulators help quicken the pace of initial QA testing cycles.

Cost Analysis

While utilizing real devices is advisable from quality and comprehensiveness standpoint, the costs also need to be accounted for, especially test budgets. Let‘s do a sample cost comparison:

• Acquiring and maintaining a test lab with the 10 latest high-end iOS and Android phone and tablet models costs over $15,000 upfront and thousands more per year for operating costs like device replacements, platform updates, etc.

• On the other hand, leveraging cloud-based real devices access allows securing test coverage across 100+ niche tablet and foldable models for less than $1,000 a month, with no infrastructure headaches.

As you can imagine, there is 10-100x cost differential, making real device cloud solutions extremely compelling financially.

Best Practices for Utilization

Given the diverse strengths and weaknesses outlined so far, what would an ideal utilization strategy look like combining real devices (on-premise or cloud), emulators, and simulators?

As you can see from the chart, in the initial stages of the dev cycle, majority of testing time is on emulators and simulators which provide faster iteration speed. Nearing launch, there is a switch to comprehensive testing on real devices targeting priority phone and tablet models to validate quality.

Emulators are great for quick sanity checks during code development thanks to robust debugging features built-in. Simulators facilitate prototyping and iterating on UI changes rapidly. Real devices should ideally handle the final 20% of validation pre-release or production deployment after core functionality has stabilized.

Let‘s discuss some other best practices as well:

Combine Real & Virtual Devices

Restrict testing to just one device type – real or virtual and critical issues can slip through the cracks. The optimal strategy is use integrated emulators, simulators and real devices in tandem to maximize coverage.

Leverage Real Device Clouds

Maintaining an extensive internal device lab with comprehensive cross OEM, platform and version coverage is incredibly expensive and operationally complex. Real device cloud solutions offer a flexible on-demand alternative with multitude of niche devices available instantly with minimal overhead.

Prioritize By User Base

Align your device coverage proportional to your target user footprint. If 90% of your customers use the latest iPhone model, prioritizing iOS simulator testing makes sense over niche Android models with minimal usage among your segments. This allows optimizing allocation of test time effectively.

Emulator and Simulator Capabilities Deep Dive

Finally, let‘s do a deeper dive specifically on some of the richer capabilities available through emulators, simulators and related tools:

Advanced Debugging Features

Android emulator‘s Dalvik Debug Monitor Service interfaces allow granular visibility into app status and smart debugging powered by breakpoints, call stack examination, memory inspection and other advanced features unavailable on production devices. iOS simulator builds upon XCode debugging functionalities with additional logging and insights into app lifecycle transitions. These simplify tracing and fixing issues exponentially easier compared to real devices.

Device and OEM Customization Extensions

Extension modules allow emulating additional sets of sensors including light, temperature, pressure etc. Other customizations around notch, hole punch screen configurations, biometric sensors etc. can mimic newer device models more accurately. Network profiles enable simulating different carrier connectivity bands, speeds and latency scenarios within the virtual test environment itself.

Automation Efficiency

Emulators and simulators seamlessly integrate into CI/CD pipelines for executing automated test suites without any external infrastructure dependencies. Parallel test execution allows validating across combinations of Android API levels, iOS versions, device profiles etc. with minimal incremental effort. Running the same automation suite across real devices in parallel needs complex, reliable setup.

Cloud Access Enhancements

While cloud simulator access remains limited currently, emulator capabilities offered through Google‘s Firebase Test Lab allow test parallelization across 20-30 Android OS images simultaneously in the cloud – all dynamically created on demand and managed via their automation APIs.

Conclusion

I hope this guide offered you a comprehensive overview into efficiently leveraging real devices, emulators and simulators for building resilient test coverage and catching critical defects before they impact customers. Each device category offers distinct strengths – speed and debugging power with virtual devices vs. realism through real phones and tablets. An integrated approach combining both maximizes development velocity, quality and cost efficiency.

The right choices come down to balancing test environment diversity, execution cycles and budget. I would be happy to discuss your specific use case and requirements to advise an optimized quality validation approach for your app. Feel free to reach out with any additional questions!