A Tester’s Guide to Simulators, Emulators, and Real Devices

A Tester’s Guide to Simulators, Emulators, and Real Devices

Posted on - Jun 28, 2022 | 3 min read

What are Automation Frameworks?

Do you know the ultimate secret of Mobile App success? It’s ‘Superior User Experience’! After all apps are made for end-users who are indirectly the final customers. In today’s digital world users are spoilt for choices, hence customers are truly kings. According to Statista, as of Q1 2022, there were 3.3 million apps on Google Play and 2.11 million apps on Apple App Store – all vying for the attention of 6.3 billion smartphone users! The obvious question then is: How do we ensure superior user experience? Or in simple terms, how do we get the attention of 6.3 billion smart phone users? Your app has to be that good, to attract and retain users who may be located anywhere across the world. Here’s where mobile app testing comes to your aid.

Mobile App Testing enables enterprises to build applications that are scalable and accessible across multiple platforms. As you already know, it's a process of certifying the app software by testing it for its functionality, usability, performance, stability, and consistency. An important area that defines the robustness of the testing system is the device that is used for running tests. These devices are classified as follows:

  1. Virtual Devices which are further classified into two categories:

    1. Simulators and
    2. Emulators
  2. Real Devices.

A Virtual Device is a software program that provides simulation, for testing the important features of an actual mobile app. It mimics real devices and is cost-efficient, but it lacks accuracy and reliability. As mentioned earlier, virtual testing can be done through either Simulators or Emulators.

Simulators mimic the internal behavior of a device without considering its hardware. Simulators are software programs that allow your device to run specific programs built for different operating systems. They are written in high-level languages and are primarily used for iOS devices. iOS Simulator for app testing is often used to ensure that the app works correctly across different environments as intended.

Emulators emulate or imitate the experience of a device. They mimic the hardware, device software, and the OS of the actual device and are more adept at imitating the device’s functionalities. Emulators are used in automation, unit testing, and debugging.

Real Device testing is testing of web, hybrid, and native apps on physical devices. For Mobile Apps it means running the various tests on actual physical mobile handsets to check the app’s functionality. This gives a better guarantee of the app working seamlessly on the end users’ handsets.

For a better understanding of each type of device, we will first see how Virtual Devices and Real Devices compare with each other and then explore the differences within the Virtual Devices viz. Simulators and Emulators.


Virtual Device Testing –
(Emulators & Simulators)

Real Devices

Virtual Device Testing i.e. Simulators and Emulators are not physical mobile devices but software that gives the same functionality as a real phone. 

Real Device Testing is testing done on actual physical mobile devices.

Virtual Device Testing cannot imitate the battery, network, and other performance issues.

With Real Devices, battery, network, location, notification and other performance related issues can be flawlessly tested real-time. 

Virtual Device Testing is suitable for some types of functional test case executions.

Real Device Testing is better suited for real-time performance testing. 

Costs are lower for Virtual Device Testing.

Real Device Testing can be expensive as various devices need to be bought to ensure that the app works well on each type of handset.

Virtual Device Testing permits cross-platform testing.

Real Device Testing does not support cross-platform testing.

Virtual Device Testing is less reliable as it only imitates the real device and not the hardware or software conditions that might change regularly.

Real Device Testing gives accurate results and is more reliable since it’s done on actual devices. 

Generally, most Virtual Device Testing is open source and free. 

Real Device Testing is not free or open-source as it involves physical handsets that need to be bought or accessed form a cloud-based device lab.


Having seen the difference between Virtual Device Testing and Real Device Testing, let’s now explore the differences within Virtual Devices itself, to get a deeper understanding of Simulators and Emulators.



Simulators create the environment that mimics the behavior and configuration of a real device.

Emulators mimic all the software, hardware, and operating systems of an actual device.

A Simulator is a partial re-implementation of the existing software.

An Emulator is generally a total re-implementation of the existing software.

Simulators simulate or imitate the internal state of a phone.

Emulators emulate or imitate the outer behavior of a phone.

Simulators are preferred for testing the mobile’s internal components like firmware, internal hardware, etc.

Emulators are preferred for testing a mobile’s external aspects e.g. transactions, calculations, etc.

Programs for Simulators are written in High-level language.

Programs for Emulators are written in Machine-level assembly language.

Debugging is not always easy in the case of Simulators.

Emulators are more reliable and suitable for debugging.

Simulators work faster as there is no binary translation.

Emulators have binary translation which slows them down.

Example of a Simulator: iOS Simulator.

Example of an Emulator: Android SDK.


Virtual Devices as well as Real Devices will come with their advantages and disadvantages. The important thing is to make an informed decision when choosing what best suits the organization and SDLC stage. To help make this decision easier, we will run through the advantages and disadvantages of both types of testing devices.

Advantages of Virtual Device Testing             

  • Virtual Device testing has a cost advantage.
  • Facilitates testing across platforms.
  • Makes recording of results easy as screen shots of the bugs can be easily taken.
  • Virtual Devices are more easily available – often being open source and free.


Disadvantages of Virtual Device Testing

  • Virtual Devices are platform-specific e.g. Emulators can test only Android devices. Hence it is important to see if the app is compatible with the platform of the Virtual Device.
  • They cannot replicate hardware configurations.
  • Due to frequent OS updates, there is no guarantee that approved results will be replicated on real devices.
  • Rendering issues of screenshots may be encountered under different OS versions.
  • Real-time environment is very dynamic and volatile and this cannot be replicated on Virtual Devices. There will be battery issues, network fluctuations, internal storage issues, calls between transactions, etc., which cannot be tested on Virtual Devices.


Advantages of Real Device Testing

  • Real Device testing is done on actual devices in a real-time, live environment and therefore accuracy of results is far greater than in virtual device testing, since the latter cannot capture real-time volatility.
  • Actual user experience of memory, size, CPU, battery etc. can be gauged on Real Devices, which is important because as mentioned at the beginning, superior user experience decides the future and success of the app.
  • Performance glitches are much more easily identified on Real Devices.

Disadvantages of Real Device Testing

  • Cost factor of buying, maintaining and managing Real Devices is the biggest disadvantage of Real Device testing.
  • Real Devices slow down the debugging process in the early stages of the SDLC.
  • Device fragmentation also poses problems as new devices are frequently launched; there are frequent software upgrades; and also various operating systems.


The foregoing analysis makes it obvious that Real Device Testing generates more confidence than Virtual Device Testing. This is due to the very dynamic real-time environment and frequent updates and innovations in the digital world, which could relate to hardware, software or OS. But the cost factor can be a major dampener for choosing Real Devices. However considering the security and confidence that Real Device Testing offers, it is often the preferred choice, as the cost of rework can also be quite high when the real-time results differ from the testing done on Virtual Devices.

Cloud-based Real Device Labs/Farms come as the saving grace to this dilemma faced by testers. They offer the advantages of testing on Real Devices in real-time environment and yet eliminate the costs of setting up one’s own device lab. Mobile testing pyramid approach is also of great help enabling Agile teams to bring efficiency to their mobile app testing process. The crux of this approach is that it helps you cope better with the ever-increasing numbers of devices and platforms.

In the larger analysis and from the long-term perspective, Cloud-based Real Device Testing is the best, more convenient, reliable and economical way forward for organizations that have don’t find it viable to have their own Real Device Lab. Cloud-based testing also enables real-time analytics on the app’s performance, which helps early detection and fixing of bugs, thus avoiding costly rework and delays. This is very important for this industry where time is of great essence.

If you are a software developer, individual tester or an enterprise with minimal functional resources, BOTm will prove to be an economical and yet secure solution for you mobile app testing needs. BOTm gives you real time cloud access to multiple mobile devices of your choice, with remote access for successful mobile app testing. It has its very own secure data hub, on a dedicated browser cloud, which offers you a zero-investment, yet safe and error-free mobile app testing option on real devices. It also has a super easy user interface, to help you get the most out of Mobile App testing.

For enterprises with a continuous need for testing experience, BOTm offers an on-premise device cloud hub, where the necessary hardware and software is provided, to set up your own secure access lab with complete control. With an entirely pre-configured set up, you get the benefit of zero-hour installation. All you need to do is – plug and play!

BOTm consistently incorporates the latest in the software testing space to ensure that you are at par with technology. Get yourself a free trial at botmtesting.com and experience quick, error-free testing on cloud-based real devices.