Mobile Testing — Comparing simulators and emulators

Functionize's mobile app testing platform implements several levels of virtualization. Here we discuss the difference between simulators and emulators.

Functionize's mobile app testing platform implements several levels of virtualization. Here we discuss the difference between simulators and emulators.

April 13, 2019
Joe Schramm

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Functionize's mobile app testing platform implements several levels of virtualization. Here we discuss the difference between simulators and emulators.
A solid strategy for mobile testing must balance speed, device-OS coverage, and high degrees of accuracy. Central to this discussion is the difference between simulators and emulators.

Many mobile app teams employ a mix of simulators, emulators, and real devices. Each tool has its place in the development pipeline. Typically, an emulator is good for native development and early prototyping. Simulators become more important during integration. Further downstream, most teams must do some testing on actual devices. Today, there are other options.

How good would it be if your team could exploit the advantages of AI and cloud-computing to thoroughly test your mobile apps across all device-OS combinations?

Balancing simulators and emulators

Although most functionality is testable using simulators or emulators, the app must get validation on an actual device. Unquestionably, it’s necessary to perform some level of real-device testing before deployment. However, it’s tedious and slow to attempt real-device testing in development.

A major concern is that many simulators aren’t good tools. This is largely because some vendors fail to keep pace with vendor updates. The challenge is to find a suitable mix of solid emulators and simulators. With complex apps, it’s also important to effectively automate much of the testing.  

In this article,  we compare simulators and emulators. Also, we explore the need for real-device testing. Then, we look at how to leverage automation in managing complex mobile device testing programs. 

Before we get to that, let’s spend two minutes exploring some benefits and drawbacks of different mobile app testing tools.

How does an emulator differ from a simulator?

Many people think these tool are the same. To them, these are tool that merely digitize an actual device for the purpose of testing. However, in fact,  simulators and emulators are quite different types of tools.

The purpose of an emulator is to precisely reproduce (emulate) the interaction with an actual device. The actual device might be a computer, tablet, or smartphone. For example, an emulator for an iPhone X duplicates all aspects of that type of iPhone. This includes all interactions with the hardware. A test application is set to run in the emulator—without modification. A solid testing regimen will explore all possible interactions of the app with the emulated mobile device.

A simulator is quite different. It lacks an important part of mobile device testing. A simulator provides a safe environment that simulates the OS for the device. Some tools do this well. However, it doesn’t duplicate interactions with hardware. In a simulator, you’ll encounter the OS and the various possible screen sizes for a device family. You won’t ever any of the potential problems that would trace to the hardware. Because of this limitation, many apps will operate somewhat differently from the actual device. This is why many testers have come to view simulators as unreliable.

Mobile device emulators

A good mobile emulator is better than any conventional simulator. That’s because an emulator simulates both the OS and hardware.

We realize that this doesn’t paint the entire picture. But for now, let’s consider the general positives and negatives for emulators.

Advantages: An emulator is device-specific, so it closely duplicates both the OS and the hardware. The test app can run without modification. Because it emulates hardware, you’re likely to find unexpected responses during testing. Typically, a device/OS vendor provides an emulator as a free, open-source tool. Most emulators integrate with an IDE for convenient testing by developers. 

Disadvantages: Because they duplicate hardware interactions, mobile device emulators are quite slow. Moreover, a mobile device emulator doesn’t account for real-device factors such as battery stress or depletion. Nor does an emulator simulate conflicts with other common apps. The setup effort can be quite extensive. Moreover, you may encounter incompatibilities with the test app. Consequently, you’ll need to build patches to bridge those gaps.

Mobile device simulators

Simulators are faster, but don’t duplicate hardware interactions.

Advantages: Most simulators have decent performance since they only simulate the OS. Typically, it’s easy to set up a simulator. The value of a good simulator is that it provides the means to quickly explore  OS interactions for the test app.

Disadvantages: Yes, a simulator can be somewhat helpful in finding unexpected behavior. However, these tools are prone to false positives. 

There’s a huge gap with any simulator since the hardware is left out of the picture. Not infrequently, a test app will run differently in a simulator. Also, too many simulators provide results that are difficult to analyze.

Summarizing the comparison

Both simulators and emulators are suitable for early testing of mobile apps. There is little incentive for developers to set up expensive testing with real devices. Though there are gaps to be expected, there are some iOS and Android tools that support early testing. Many of these simulators and emulators also offer easy setup of different OS versions.

Actual-device testing

Real devices are, well, the real deal.

There is no better validation than deploying and testing on an actual device. You get actual usage and see the interactions as the user will experience them. The app performs on a specific OS version—running on real hardware. With proper coverage, you’ll engage with all factors that may induce a fault or anomaly.

Advantages:  Tests run in the actual environment, with real conditions. These conditions include varying weather, temperature, locations, and networks. Additional insights should arise from good test case coverage in such actual conditions. For example, screen viewability is directly testable with varying lighting conditions. Also, actual-device performance is typically faster. Moreover, it’s easier to test for interoperability. Bug replication is also easier. On the real device, there are no false positives. And, testing is done on an actual OS release from the manufacturer with the latest updates (or not!).  

Disadvantages: Since there are thousands of mobile devices-OS combinations, thorough real-device testing is a daunting prospect. Remote testers may not have access to the real devices. Device inventory and maintenance can be tedious. Also, it’s difficult to get a device that is only available in other countries.

Seeking a better mobile app testing solution

The pressing need here is to find a simulation tool or platform that is dependable, accurate, scalable, and economical.

With so many combinations to test, you’ve got to be able to quickly configure and execute tests—in parallel. For most mobile app teams, it’s vital to test across a wide variety of OS/device types. You’ve also got to stay on top of OS updates. When you combine all of this complexity with your app development, manual testing alone is woefully inadequate. Intelligent automation is a must.

Here are the essential considerations for automated mobile device testing. Functionize is the only platform that can fully satisfy all of these criteria.

Highly scalable parallel testing

Parallel testing enables your team to release more frequently. Today, it’s truly possible to automatically test many multiple virtual devices. All at the same time, whenever you want.

Cost savings

Emulators and simulators must prove to be much more economical than real-device testing. Is your current solution capable of running functional tests across the widest variety of OS-device combinations? Done properly, an automated simulation platform can perform exhaustive mobile app testing at a fraction of the cost.

Quality improvements

As the highly competitive mobile world increases in complexity, quality is really what it’s all about. Because simulation is virtual, large economies of scale can be brought to bear. You can run many, many more parallel tests. This reduces build times so that you can iterate more. And, you’ll deliver better software. The happy result will be a continuous improvement to the experience of your users.

Highly accurate

You want a solution that exploits the power of cloud computing to achieve the highest accuracy. And, you want this accuracy to be seen across the entire device-OS spectrum. If you can rely on an automated mobile testing solution, you’ll spend less effort testing. More time can be spent on development and exploratory testing. You’ll waste less time evaluating false-positives that result from unthoughtful, incomplete testing solutions.

Testing on-demand

With a highly scalable, cloud-computing solution, you’ll rarely wait on the results of a simulator. Imagine the extra time you’ll enjoy because you can quickly launch whatever automated testing resources you need—on demand. Test on your schedule. There’s no need to wait for another tester to finish their tests.

Functionize: Extensive mobile device coverage and precision

Any worthy test automation solution has to precisely target a broad range of mobile operating systems and hardware devices.

Are you ready to say goodbye to versioning and compatibility issues in your mobile testing efforts? It’s true, you can move well past testing the very latest device-OS release. With the Functionize automation platform, testers without any coding skills can easily validate your app. You can do this on the latest release, and on hundreds of other device-OS combinations.

Flexible, rapid scaling of mobile testing can be challenging and expensive for an individual team. And, it diverts precious human resources. High-performance, highly accurate emulation is compute-intensive for most organizations. This is largely because virtualizing a mobile device or desktop PC requires hardware acceleration. Functionize can make this practicable for your team and help keep your costs down. 

Integral to the Functionize automated mobile app testing platform is our strong collaboration with Google Cloud. Combining our proprietary machine learning technologies with Google Nested Virtualization (GNV), Functionize achieves very high levels of mobile device simulation. Actually, our mobile app testing platform implements several levels of virtualization for each device-OS combination. Starting with a VM testing, our system adds hardware virtualization layers using GNV. 

Ready to move boldly into the future with highly automatable, highly scalable mobile app testing? Get in touch with the Functionize team today.