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Posted August 31, 2021

Better Together: Why You Should Leverage Emulators and Simulators for Web App Testing


The mobile vs. desktop battle for web supremacy is neck and neck, and mobile has the advantage. Mobile devices now account for about half of all web traffic worldwide, a figure that’s expected to rise to nearly 75%—or over 3.7 billion people—by 2025.

Websites that are difficult to use, buggy, or slow to load on mobile devices are bad for business. Here are some reasons why, according to Google:

  • Mobile-friendly websites rank higher in Google’s search results.

  • Mobile searches account for more than half of all Google searches.

  • Visitors are five times more likely to leave your site right away if it’s not mobile-friendly.

  • Nearly half of visitors will leave if the pages don’t load within three seconds.

With half of your customer base preferring to access the web via their mobile devices, are you testing your site to make sure it delivers the same exceptional experience to both your mobile and desktop users? If the answer is no, then you’re leaving behind a significant customer base and putting your company’s success at risk.

Time to adopt a mobile-first strategy

Organizations are recognizing that mobile is the future. Some are even moving to a mobile-first design strategy, where products are designed from the start to be mobile-friendly, versus designed first for desktop. Companies like YouTube, Apple, and Airbnb have all embraced mobile first in the last few years.

In addition to designing your web app to be future-proof, the thinking behind mobile-first is that it’s easier to scale a product made for the small screen up rather than down. This is based on the concept of “progressive advancement,” or prioritizing the most important functions and features of your product based on what can fit on a mobile screen and then designing for progressively larger screens.

The opposite of progressive advancement is “graceful degradation,” where the product design prioritizes bigger screens and back-fits the components and user interface to fit smaller screens. However, this method essentially makes mobile an afterthought and delivers a lacking user experience as a result.

Mobile first extends to testing as well. Ensuring your site is responsive across operating systems (OS), browsers, and devices should be an integral part of your testing strategy. 

However, ensuring your web app delivers a flawless user experience across so many different access points can be intimidating for testing teams. But it doesn’t have to be. Incorporating virtual devices like mobile emulators and simulators into your automated testing suite can help lighten this load.

Why use mobile emulators and simulators to test your web application?

Virtual devices, or mobile emulators and simulators, allow you to see how your website behaves and is displayed on different OSs, browsers, and devices. While the two terms are often used interchangeably, they do have some differences.

Simulators are used for iOS devices and emulators are used for Android devices. However, while a simulator can replicate what your site looks like on an iOS device’s interface, it cannot run the real device’s hardware, or operating system (OS). Emulators implement the Android OS as a virtual machine (VM) on a desktop PC or as part of a cloud testing platform, allowing for testing of both the software and hardware.

Because they’re software-based, virtual devices are easier to provision than real devices. Virtual devices also enable parallel testing and automated testing via external frameworks like Appium. This brings real benefits in the way of speed, scalability, and cost savings.

Here are some additional benefits to incorporating virtual devices into your automated testing suite.

Expand testing coverage

Emulators and simulators allow you to expand your testing scenarios without requiring access to each real device. For example, the mobile and macOS versions of the Safari browser have some significant differences. While testing each scenario manually would be extremely time consuming, emulators and simulators can help you do this more accurately and efficiently.

Catch buggy behavior faster

Virtual devices help tighten the feedback loop from development to exploration and back again. Web developers can test builds in their coding environment as they work, allowing them to identify and fix bugs in real time. 

Adapt legacy web tests for mobile

Some organizations have yet to transition their legacy software applications to mobile, or are behind in their efforts to do so. For these teams, building an automated testing suite for mobile from scratch or porting existing test cases to mobile can be a heavy lift, or they may not know where to begin. 

Emulators and simulators are a great starting point in this situation. These tools allow testing teams to use existing web tests without having to significantly rework their test frameworks. 

Why a balanced testing strategy is best

Some organizations take an either/or approach when testing their web applications: they either use only real devices, or they only use virtual devices. 

However, there are drawbacks to using each method alone. Real devices are more costly and difficult to scale. On the other hand, emulators and simulators can’t fully replicate device hardware or deliver a real-world testing environment. 

A best practice is to take a balanced approach to mobile testing. Incorporating both virtual and real devices will increase the scalability, efficiency, and effectiveness of your mobile testing plan while still allowing you to test real usage scenarios and conditions.  


A painful user experience, impatient visitors, and being invisible on Google will all cause your organization’s digital confidence to take a huge hit. Managing your mobile presence and ensuring your website will look, function, and perform exactly as it should on every browser, operating system (OS), and device, every single time, will increase this confidence, delight customers, and increase your organization’s visibility in Google search results. 

Ashwini Sathe
Sr. Group Product Marketing Manager
Aug 31, 2021
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