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Mobile device testing: What is an Emulator?

Emulators have become common tools in mobile app development. But what exactly are emulators? How do they related to mobile device testing?

If you’ve ever wondered what an emulator is, you’re not alone. You may even be considering using an emulator in your own mobile device testing strategy.

In this article, we take a deep dive into emulators, how they can help with your mobile testing strategy and their limitations.


The Oxford English Dictionary defines emulation as:

The technique by which a computer is enabled, by means of special hardware or software, to execute programs written for a different type of computer. (emulation, n. OED Online. December 2022. Oxford University Press. Accessed February 16, 2023.)

More loosely defined, emulation is when we use one device to pretend it’s another device.

Emulation first became relevant to computing in the 1960s. At that time, most people would be highly unlikely to encounter computer hardware. Computing hardware was especially expensive, and hardware was usually inextricably bound to the software it was designed to run. 

Developers needed a way to simulate software so that a computer could run programs written for another device. Their solution? Emulation.

Since then, emulators have had a significant impact on software testing. Since it was not feasible to validate early software prototypes on different consumer devices, developers turned to emulators to help them. Now, they could test their software on other consumer machines without acquiring them.

The popularity of emulators only grew. For example, emulators became tools in gaming circles. Around the mid- to late 1990s, nostalgic gamers developed emulators to play difficult-to-find arcade games and obscure games from older consoles like the Commodore 64.

Fast forward to today, and now we have access to thousands of different mobile devices on other operating systems, and in different versions. The reason? Developers need a way to test their mobile applications in a way that mirrors the user’s experience.

What is an emulator? How does it work?

Emulation has two actors: The host and the guest. The goal of an emulator is to allow a computer or mobile device (the host) to behave like another device (the guest). It does this by recreating the guest device. But an ideal emulator is more than imitating a machine’s software; it also programs the machine’s hardware, allowing it to respond the same to actions. 

Emulation breaks down into two primary levels: High-level and l0w-level.

  • High-Level Emulation involves simulating the functions of the hardware but not the hardware itself. The goal is with this level is to be good enough.
  • Low-Level Emulation involves emulating—as closely as possible—the hardware, all the way down to its components.

The use of emulators in mobile testing

A mobile device emulator is a complete implementation of a mobile device written in machine assembly language. From the behavior of the hardware to the operating system, a mobile device emulator is as close to the real

thing as it gets. Testers render the device emulator on their PC so they can test the functionality of their application on different devices. 

In the case of iOS and Android, the emulators were developed by Apple and Google for development and testing. Each emulator is available in their respective SDKs. Different testing frameworks like Appium and Espresso also leverage mobile device emulators to create and automate test cases across other devices.

Benefits of using mobile device emulators

Emulators provide developers and testers flexibility and allow organizations to save money and resources that would’ve been spent on acquiring real devices, setting up test environments, and other hassles. In their ideal state, emulators provide the following benefits:

  • Less Maintenance: Using emulators saves effort in configuration, deployment, and device management.
  • Less expensive: Emulators are an often free alternative to testing on a live device. 
  • Less time: Save the time it takes to acquire instruments and run tests. You can run concurrent tests on multiple emulators simultaneously, whereas a live device requires tests to run individually. This makes testing much faster, so you can receive instant feedback.

Limitations of using mobile device emulators 

Close as it may be, the environment of the emulator is—and this is important—not real. Naturally, that comes with its disadvantages, such as:

  • Network: The real world consists of connectivity, bandwidths, 4G, 5G, WiFi, competing signals, and background downloads. An actual device interacts with these network changes much more organic way than an emulator or simulator can. 
  • CPU and Memory: As different processes run simultaneously on your mobile app, the CPU must meet demand. An emulator cannot know how much memory an app uses or its effect on the CPU, which are essential aspects of mobile testing.
  • Battery: Emulators can’t assess an application’s effect on battery consumption. Nor can it test app performance at extreme ends of battery life. 
Image: Sofy x Blue Flourishes, Shutterstock

Real device testing

You just can’t beat the real thing. Yet traditionally, with so many devices out there—and with more appearing all the time—it hasn’t seemed feasible to go any other route than emulators. Real device testing is much more accurate but requires significant costs, resources, and time to adopt.

So, what’s a software engineering team to do?

Testing real devices on the cloud

Fortunately, there’s another way, and it combines the best of both worlds: Cloud-based access to a real device lab.

A real device cloud lets you acquire, install, and test your application on an actual device. These are accessed virtually, but unlike emulators, they’re real: Real hardware, real components, real network.

With tools like Sofy, you can leverage hundreds of devices from the cloud using Sofy’s Real Device Lab

App developers and testers use Sofy to create no-code test cases and automate them across dozens of real devices. With Sofy’s Real Device Lab, you can:

  • Grab a real device, perform a manual test, or automate it.
  • Access a library of cloud-based, well-maintained real devices. Every time you acquire a new device, it comes with a clean and prepared environment with your app installed.
  • Record a test once and automate it across hundreds of real devices.
  • Record real-time issues and collaborate with your team to work on resolving them.
  • Analyze code changes to detect impacts on the existing test suite and automatically make updates.
  • Integrate seamlessly with your CI/CD tool for upstream improvements.

There’s no need to compromise

Emulators provide amazing advantages for software developers. They have made device testing much easier, quicker, and cheaper. 

Yet they’re not without their limitations—and those limitations can make or break the performance and success of your app.

It’s important to weigh the pros and cons of emulators and try to incorporate real devices into your testing strategy wherever possible. Tools like Sofy make that possible.

Disclaimer: The views and opinions expressed above are those of the contributor and do not necessarily represent or reflect the official beliefs or positions of Sofy.