Emulator vs. Simulator: Demystifying the Differences

Understanding the differences between emulators and simulators and their relation to actual devices is a fundamental aspect of mobile app development.

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Image: Sofy x venimo, Shutterstock

Mobile app testing is an essential step in the development process to ensure that applications are bug-free and working as intended. Two common ways developers run these tests are through the use of emulators and simulators. 

While the terms emulate and simulate may seem similar — and are even sometimes used interchangeably by test engineers — the truth is that there are some key differences between them. Understanding those differences is key to making the most of their unique advantages. 

To clear up any confusion, let’s take a closer look at what emulators and simulators are, how they differ, and when to use each when mobile app testing. We’ll also look at how they stack up to real device testing and explore potential ways to use a hybrid testing model. 

Simulator vs. emulator — what do they have in common?

Before we dive into the differences between simulation and emulation, it’s worth briefly discussing what these two practices have in common. Both approaches aim to create a fast, convenient, and flexible virtual environment for conducting software tests early in the development cycle. 

While simulation and emulation can’t replicate certain functionalities and are more prone to errors than real device testing, the fact that they are much faster, easier, and cheaper to set up makes them valuable tools for identifying problems early on. They also allow teams with more restrictive budgets to test across a wider range of devices and configurations.

The technological difference between emulators and simulators 

While they are both virtual environments that play roughly similar roles in the development pipeline, the way these techniques approach that role is quite different. 

At its core, emulation seeks to create an exact copy of a specific device by mimicking its hardware and software. This allows developers to test their apps in the closest thing to a real-world scenario. Emulation can be extremely useful when an app needs to interact with certain hardware features, sensors, or operating system functionalities since a quality emulator can mimic these features as closely as possible. 

On the other hand, simulation creates an environment that imitates the behavior, variables, and configurations of an app’s software, without any attempt to replicate hardware. Additionally, unlike emulators, simulators aren’t only limited to running in real-time. For those reasons, DevOps engineers often consider simulation a more abstract or hypothetical form of testing, as it is often used for test cases that would be impractical to test on emulators or real devices. An example might be software behavior that’s modeled over lengthy periods of time.

Another key difference that will influence a developer’s choice to emulate or simulate is speed and resource usage. Because a simulator only has to model the behavior of the device and doesn’t have to perform binary translation, it’s almost always a faster, less resource-intensive, and lower-latency option. However, that comes at the price of being unsuitable for real-world, practical use cases. 

Simulation vs. emulation in specific use cases

So when should you use an emulator or a simulator? The answer depends on what kind of information you intend to collect and measure during testing. In many cases, developers will use a hybrid approach that combines both testing methods early in the development cycle. Later in the cycle, they might transition to real device testing. While this is a thorough way to avoid potentially embarrassing issues at launch, it’s also the lengthiest and most resource-intensive method. It also may not be suitable (or necessary) for some applications. 

Generally speaking, simulation is useful for testing app performance when underlying hardware is unlikely to impact the results. This includes screen resolution testing and display aspect ratio, data transfer between applications, testing cloud-based applications, or testing applications designed to be device-agnostic. 

Conversely, emulation is better for practical use cases where hardware and software interact or work in tandem. In this sense, you might consider emulation an intermediate testing step between simulation and real device testing, providing developers with a reasonably accurate picture of how the app will perform during real system use. If your app’s performance depends on factors like a device’s specific CPU, memory allocation, or firmware, emulation will provide much more accurate results than simulation. 

Still, emulators for mobile testing also have their limitations. For example, they cannot fully replicate many modern device functionalities like GPS or touch-screen capability. It’s also possible for emulators to return false positives due to emulator malfunctions and unaccounted testing conditions. Finally, emulators usually provide an ideal environment for testing, whereas real-world use can introduce many less-than-ideal variables.

A hand holding a real mobile device

Image: Sofy x TopRated, Shutterstock

The benefits of real device testing

While emulators and simulators are an easy and inexpensive way to conduct early tests and catch the most obvious issues, launching an app without conducting any real device testing is a disaster waiting to happen. 

There is simply no substitute for the more accurate real-time performance and superior validations that real device testing can offer, especially as it relates to the actual user experience of your application. 

A virtual environment can’t replicate certain features, like the look and feel of your app or its usability in varying conditions (such as in direct sunlight or nighttime conditions). However, these are often the exact issues that are most likely to turn users away.

Keep in mind that you only have one chance to make a first impression. If you wait until the app is in the hands of your customers before realizing that there are usability or visibility issues under common real-world conditions, you are going to have a very costly and embarrassing problem to fix. 

But despite the clear benefits of real device testing, the problem remains that building and maintaining a well-stocked device library for mobile app testing is a time-consuming and expensive venture. It requires a staggering number of variations between different devices, operating systems, and screen sizes, and this number only increases daily as manufacturers release new versions. When you add in the storing, charging, updating, and repairing of these devices, it becomes a seemingly overwhelming task.

The best of both worlds

Luckily, Sofy has harnessed the power of the cloud to give developers access to an extensive real device lab directly from their browsers, providing all the advantages of real device testing while eliminating the financial and logistical hurdles. 

With Sofy’s device lab, developers can avoid the uncertainty and guesswork associated with simulation and emulation. Now, they can set up real device tests in just minutes so that they can spend more time on QA testing and less time searching for the right builds and environments. 

Sofy seamlessly integrates with your existing development tools, creating a unified UI experience that lets you run ad-hoc, manual, and automated tests with the click of a button. It also gives you access to detailed, automatic crash logs that make it possible to quickly identify, replicate, and correct any issues that arise during testing. 

If you’re looking for a way to conduct accurate real device testing across a wide range of devices but you don’t want to deal with the headache and overhead that the traditional approach requires, try out Sofy for free today to see how we can help you supercharge your mobile app testing efforts. 

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.

 

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