As of the second quarter of 2020, the number of available apps on the Google Play Store was 3.6 million, followed by 1.82 million on Apple App Store. This represents a 6% increase for Google Play Store and a 6.95% increase for Apple App Store than the previous quarter. Statista also projects a rise in the number of app downloads, more than 350 billion by 2021.
Mobile applications are now an integral part of daily life. Therefore, it’s no surprise that most enterprises have made app development an essential feature of doing business. However, for any mobile app to be successful, top performance is paramount. Otherwise, end-users will uninstall your app, find and replace it with an application that performs better. AppsFlyer notes that more than one in every two downloaded apps is uninstalled within 30 days.
Today’s digital-savvy app users have no tolerance for slow-performing and sluggish apps with errors or crashes. If your app doesn’t perform on all fronts, users won’t hesitate to uninstall it and find a better replacement. This explains why your mobile app needs to be thoroughly tested before it’s released to the end-user.
This guide covers a range of topics to provide you with a basic understanding of mobile apps performance testing. For example, it includes performance testing types, mobile apps performance testing tools, the overall strategy for successful mobile apps performance testing, and more.
Let’s begin, shall we?
What is Mobile Application Testing, and Why is it Important?
Mobile app performance testing involves evaluating an application to ensure its working as expected under varying performance indicators and predicting a user’s experience before making it available to the end-user. As such, the performance testing of mobile apps ensures that app functionalities work as specified by finding and solving bugs and identifying and eliminating any app performance bottlenecks.
The goal is to derive insight into an app’s aspects, such as speed, robustness, correct sizing, and scalability. Without mobile apps performance testing, your end-users may encounter poor app performance, user experience, and usability across their different mobile devices. Mobile app performance testing can be used on all types of mobile apps – native , hybrid, or web-based.
Types of Performance Testing
For a deeper understanding, let’s look at the different ways you can test the performance of your mobile apps.
1. Load Testing
Mobile app load testing evaluates if an application’s performance can handle the required number of users and still operate and perform at an optimal level. It measures an app’s performance under normal and peak conditions (an increased number of users) to reveal any app software bottlenecks.
2. Stress Testing
Stress testing measures an app’s performance under extreme working conditions. It intentionally pushes an application beyond normal load conditions to identify which components fail first. Specifically, it reveals the app’s breaking point, which helps measure the robustness and ability of an app’s data processing and response to high-traffic volumes.
3. Capacity Testing
Capacity testing tests how many users an app can handle before performance drops below the permissible levels. It helps anticipate performance issues scalability-wise and future user-base growth.
4. Volume Testing
Also known as flood testing, volume testing evaluates an application’s ability to handle and process large amounts of data without slowing or breaking down or losing any information. It determines the overall capacity of an application.
5. Spike Testing
Spike testing is closely affiliated with stress testing and measures an app’s ability to perform under sudden jumps in workload or volume increase. It’s done by rapidly increasing the workload caused by a massive number of users to see whether the app will fail or aptly handle the sudden changes in load? Spike testing is critical for applications that experience considerable surges in the number of users.
6. Scalability Testing
Scalability testing determines an app’s ability to handle and process an increasing workload. It involves measuring metrics including response time, CPU usage, Network usage throughput rate, hits, requests per second, transaction processing speed, etc. Scalability testing is helpful in the planning and design development to cut costs and mitigates possible performance issues.
7. Endurance Testing
Endurance testing (also soak testing) measures how an app performs under load over time. It is a component of load testing and is executed by simulating or applying high traffic for an extended time to validate an app’s ability to tolerate extended periods of high traffic and other performance load requirements.
Strategy for Performance Testing Mobile Apps
Before the actual mobile apps performance testing, you need a plan that ensures your app is tested effectively. We recommend the following steps for successful performance testing of mobile apps.
#Step 1. Define and Align Test Objectives With Your App Goals
Lack of mobile apps performance testing goals is the most common reason why app development and performance testing fails. When your mobile performance testing objectives are clear, well-defined, and aligned with your business app goals, the testing process becomes smooth and effective.
#Step 2. Identify Test Case KPIs
Your plan needs to set and achieve the benchmarks for testing to demonstrate your performance testing’s viability. It’s how you will sustain a competitive advantage and identify if the testing execution was successful or not. While your strategic goals establish the objectives for app testing, KPIs will help you know how far you are from achieving them. These KPIs can help you measure the effectiveness of your testing;
- Average Response Time
- Peak Response Time
- Error Rate
- Concurrent Users
- Requests per Second
#Step 3. Identify and Prioritize Key Scenarios
A common reason why most app performance testing fails is due to poorly defined targets. Every performance testing should outline a specific target of test features. Not defining your target features earlier on or trying to test all app features at once can doom your testing strategy. identifying test factors gives you a leg up by ensuring that you test crucial app features first. Once confident that necessary features work appropriately, you can move on to test secondary features or scenarios.
#Step 4. Test Your App with Emulators, Simulators, and Real Devices in a Testing Environment
No matter how great your testing plan sounds on paper, it might not pan out successfully in reality. That said, it’s vital to understand user experience from an end-user’s point of view.
A testing environment evaluates your app on virtual testing devices such as Simulators and Emulators. Simulators and Emulators mimic smartphones, which helps QA testers run the software application to get a rough idea about how your app would run on the actual devices.
Although virtual testing devices closely mimic end-user devices and are cost-efficient, they cannot replace real devices. Ensure you test your app with real users on real devices.
Real devices allow you to get a first-hand experience and feel of device interfaces. You will assess the performance device-specific functions that may not otherwise be available simulators and emulators such as camera permission, GPS. Additionally, you can test over a wide range of screen resolutions and across different geographical locations and networks. More importantly, real devices provide more accurate and reliable results than virtual testing devices.
#Step 5. Align the Testing Approach with Your Application Development Methodology
App testing is often a continuous exercise over the lifecycle of an app. Aligning your testing approach with your application development methodology can help make your objectives and testing benchmarks more intentional and far-reaching. It also helps keep everyone in the development team accountable for your long-term app vision and strategy and gain insights into how your plan is performing over time.
Lastly, it allows everyone to easily collaborate, communicate while ensuring everyone is on the same page. For instance, the agile methodology requires development teams to implement continuous iteration of development and testing throughout the project’s app development lifecycle. Alternatively, waterfall requires development teams to align their workflow approach into phases – this means embracing regular bug reports and regression tests before moving to the next stage.
#Step 6. Consider the Latency and the Bandwidth of a Carrier Network
App performance can be affected by the network bandwidth and network latency. So, it can’t be overstated how much testing your app under varying network conditions can ensure good app quality and improved app performance. Mobile devices connect to tthe internet through Third-party network carriers meaning that bandwidth and the networks’ latency can vary.
Taking network carrier differences into account allows your team to optimize the app performance to improve user experience.
Performance Metrics to Ensure Mobile App Success
Now that we have a solid understanding of mobile apps performance testing basics, we’ll look at the key performance metrics to ensure mobile app success and how each impacts your business and their benchmarks.
Back-end Performance Metrics
Back-end performance metrics affect the server-side of an application.
Your mobile app might be well-designed with a great user experience and design, but how efficient is the back-end infrastructure supporting your app. Server-side load is the time elapsed when a user puts in a request to your app and the server responding to that request.
If your server’s response time lags or is slow, so does your app’s user experience. Google PageSpeed Insights recommends anything under 200 ms for server response time. A 300-500 ms range is standard, while anything over 500 ms is below acceptable standards. A slow server-side load can damage brand reputation due to negative app ratings and user reviews.
Factors that can cause server-side load include a lack of server resources, overloaded servers, memory leaks, and end-users network connection speeds. It can be resolved using reliable and fast web hosting, using CDN, optimizing databases, monitoring PHP usage, configure caching, or minifying scripts.
API Latency refers to the round-trip time between a user’s action and a server’s response to that action. Ideally, your app should be optimized to around 1 second response time seamlessly to and fro communication. With high latency, your users may uninstall your apps, actively switch to your competitors, abandon carts or leave negative reviews.
Time to First Byte (TTFB)
TTFB measures the time elapsed from when a user initially makes a request to when the first byte of the requested data appears on the end-user’s device. Typically, anything under 100 ms is great TTFB. Anything under 200ms is good.
Good TTFB ensures that application response times match your users’ expectations. Otherwise, users will abandon and negatively criticize your app, which leads to slow business.
HTTP calls structure requests and responses for effective communication between app users and your servers. The more requests your app makes with the back-end servers to complete a user request, the more likely the app will slow down or crash.
Reducing calls or requests, empty SRC or HREF tags, and avoiding HTTP 404 errors can significantly increase server response times hence more user engagement with your business. A response time of around 0.1- 0.3 seconds offers users an instantaneous response, with no or unnoticeable interruption.
Once users access your app, a DNS lookup sends a query for your domain name. This maps your app’s domain name to an IP address. Averagely, a DNS lookup should take between 20-120 ms. Reducing DNS lookups can boost application performance, improve user experience and your app ranking.
Throughput measures the volume of requests/responses/traffic your app can handle in relation to time. Have a throughput goal that your application needs to operate on – a specific number of requests per hour. Test with light and heavy real-time users. High throughput means that more transactions are completed during a given amount of time.
Front-end Performance Metrics
Front-end performance metrics affect the user interface. They include;
Application Response Time
As one of the core features of app success, mobile app response time is critical. Users have zero tolerance for long load times and sluggish processing. An ideal response time for any app is between 1-3 seconds, depending on the app type.
Optimize your mobile app performance to clock these numbers. If not, you risk losing a place in your customer’s mobile device and missing on selling your products and services. Reducing cookie size, using fewer URL redirects, eliminating components like Flash, and having fewer unique objects can help you achieve a good response time.
Average screen rendering time is the time your app takes to load its content: images, text, videos, and animations. It doesn’t do your app any good to have excellent response time with slow render times. Users will uninstall or abandon your app.
Screen rendering times differ with application complexity. A time range from 1 second for light apps to 3 seconds for complex apps is excellent. Slow screen rendering time can result from inaccurate screen dimensions, inconsistent fonts, unscaled images, excessive blocking scripts, etc. To speed up screen page rendering time, avoid CSS expressions and reference the images in HTML.
Users hate when apps crash, slow down or freeze, even for a few seconds. Frequent app crashes can quickly lead to business failure or prove costly. The crash rate is the average crashes per app load. The typical crash rate for mobile is 1 – 2% but may vary widely depending on the app type of app, app usage, maturity, etc. Always aim for 98% crash-free users.
Battery life is a critical feature of any mobile device. Apps that compromise battery usage don’t last long, and neither will your business. Heavy battery usage irks users. They won’t think twice about uninstalling your app if they realize it eats up battery no matter its significance. Mobile app battery consumption testing optimizes your app only to consume low battery power when and if necessary. Your app should also minimize background activity.
50.6 % of users will uninstall your app if it takes too much space on device memory. Memory-sucking apps prompt memory warnings, performance issues and quickly drain battery power. Even if your app launches fast but still uses a significant percentage of the user’s CPU, it isn’t performant. Users will terminate it due to poor user experience.
High memory usage apps are also prone to termination by operating systems when operating and competing with other background apps. Test and observe app functionalities to reduce your app’s memory footprint before deploying the app to end-users. For instance, push notifications have been found to increase memory consumption in Android apps.
App in Background
Users expect apps running in the background to be retrievable and remain in the same state it was before. If your app isn’t retrievable in the background, data is inevitably lost upon retrieving the app. And this means poor user experiences – a big turnoff for users.
Performance quality is relative across various mobile devices. There are thousands of mobile devices on the market that vary by brand, hardware, operating system, and price.
Test your app needs on different devices with different RAM, ROM, and processor specifications. Ensure your app performs consistently across devices with a lower capacity. It should also aptly handle high server loads and resist bandwidth and latency changes.
Usage with Other Apps
Imagine using an app that restricts other apps? Frustrating, right? When test-running your app in parallel with other apps, it mustn’t interfere with other apps. If it does, users will quickly uninstall it and leave negative reviews. Switch between apps to monitor how your app interacts with other apps.
App Load Time
How fast does your app load? If your app startup time is too slow, you’re bound to lose money. The ideal loading time for your mobile app should be about two seconds. Portent research notes the first five seconds of page-load time have the highest impact on conversion rates.
App Load per Period
App load per period refers to requests or calls a mobile device can handle in a set time. It’s essential to know the optimal load per period your application can handle since app users may click a feature multiple times. Ensure your app works well under rapid changes that affect the app’s size and load or face app uninstalls and bad reviews.
How to Setup a Mobile App Performance Test Environment
A testing environment is a setup of software and hardware on which your testing team executes test cases. Ensure you do the following for your app performance testing environment:
Understand your App and Test Environment
Before setting up the performance testing environment, it’s critical to understand the mobile app to be tested, the operating systems or devices to be tested, and the different geographic locations.
Besides, the tester should be conversant with the test environment and both app and testing architecture. Any disparity between them can increase production costs and affect time to market.
Isolate the Environment
Ensure that no other activity is carried out in the performance test environment when actively using the system. Any interference can jeopardize the test accuracy and pose issues when implementing a new bottleneck.
What’s more, having users simultaneously access the platform increases the server load and affects app performance with slow processing. Consequently, real-time app users won’t complete tasks when executing a performance task.
Leverage Test Data Generator Tools
Most performance tests depend on database records. Use data generation tools to match the database records with those in your test environment system. Importantly, take notice of data writing, reading, and deletion when doing performance testing. These actions are notorious for breaking app performance.
Isolate Your Network
Network isolation eliminates timeout errors. However, if your bandwidth can accommodate performance testers and other users, isolation isn’t necessary. Regardless, if your network is insufficient and can’t support a few concurrent activities, app performance will be affected.
Clear Proxy Servers from the Network Path
Any proxy between the client and the webserver can strain app performance. To solve this, conduct server transfers in an isolated environment.
Select the Appropriate Tool for Testing
Once everything listed above is cleared, select a suitable testing tool and proceed with app performance tests. Respective test tools are either suited for Android app performance testing or iOS app performance testing. Some tools can test both Android and iOS devices.
Top Mobile App Performance Testing Tools
Mobile app performance testing tools vary based on the type of the device and platform. Some of the most commonly used testing tools include;
Appium Studio is a free testing tool for mobile performance. It’s known for its easy-to-read and write code interface, a wide variety of supported tests, and a unique XPath. It is fully integrated with your existing testing environment and provides developers with access to device-specific features. Users can enjoy free community support.
Robotium is an Android test automation framework that offers full support for native and hybrid applications. The framework makes it easy to write powerful and robust automatic black-box UI tests for Android apps. Developers can write custom function, system, and user acceptance test scenarios across multiple Android activities. Users can also record and replay steps for conducting the test.
Selendroid is a Selenium-based test automation framework for Android native and hybrid mobile apps and the mobile web. Users can simultaneously test multiple Android apps, switch between cases that can be used on emulators or real devices. The downside of the tool is that tests are written using the Selenium 2 client API.
Sauce Labs is a cloud-based, mobile, and web application automated testing platform. It allows users to run tests in the cloud on more than 700 different operating systems, browser types, and device combinations. Developers run parallel tests that don’t interfere with one another in a controlled bug-free environment, handle large testing volumes and automate mobile tests with little programming knowledge. It also provides a secure testing protocol for testing applications behind customer firewalls.
Apica LoadTest tests the scalability of all your applications, identifies performance bottlenecks. It supports a wide range of applications and devices.
Key Challenges in Mobile App Performance Testing
Like any other development process, performance testing for mobile apps isn’t without hurdles. Among the challenges you’re likely to run up against are;
- Compliance with Industry standards and guidelines
- Mobile usability
- Multiple device-specific features and sizes
- Devices restrictions like battery life, memory, location, and resources consumption, touchscreen movements, etc.
- Simulating Network Connectivity like Edge, 3G, 4G, 5G or Wi-Fi, etc.
- UI variations
- Selection of suitable diagnostic tools and test environments
- Hardware procurement
- High concurrency
- Rapid scalability
- Time to market
Troubleshooting Performance Issues with Mobile Applications
Once you’ve tested your app, it’s time to trace and fix performance bottlenecks identified during the test run. Let’s have a look at two standard performance issues in mobile applications and how to solve them:
- Lags/delayed response time — lags are usually caused by the memory (RAM) or by caches. In such instances, clear the cache to end unnecessary processes and rerun the test.
- App crashes, unresponsiveness, freezing, hanging, or slow restarts — check the software for updates or patches or manage caches. You may also need to optimize the app code, do an automatic restore or map the application according to a device. Third-party APIs can also be used to verify if the app works accordingly.
Most troubleshooting issues can be fixed by following the steps mentioned above.
React Native apps vs. Native Apps — Comparing performance
App performance is essential when choosing the proper development framework for your app. Native, React Native, and Flutter offers the best frameworks to develop iOS and Android apps.
Here’s how Native apps compare to React Native and Flutter apps, respectively:
Regardless, developers can use Third-party tools like Appium for testing React Native apps. No official support is provided for such tests. React’s documentation also lacks any automated steps to deploy iOS apps to the App Store.
Flutter Apps vs. Native Apps — Comparing Performance
Flutter is faster than React Native but still no match for Native apps.
Native apps perform exceptionally well on CPU and GPU usage without external library kits. They can reach speeds of 60 FPS and 120 FPS even with core animations on your app.
Flutter bypasses the need for a bridge to interact with native components, drastically improving its performance. It’s also compiled into native ARM code for both iOS and Android. Flutter can also reach animation runtime speeds of 60pfs with the ability to perform even at 120 FPS. Like React, Flutter beats Native apps beats at memory consumption.
Both Native and Flutter provide a rich set of testing features to test apps at the unit, widget, and integration levels. They also have comprehensive testing features with official support. Overall, Native with heavy performance, animations, and functionality. Flutter, not far behind, is an excellent fit for innovative designs with good CPU and Memory performance.
Mobile app performance testing is vital to any app development pipeline. However, it’s not a piece of cake. It’s a major, continuing exercise that requires input and collaboration from across the entire app development chain, as well as a detailed consideration of your end-users.
It doesn’t matter which methodology or tools you’re using for mobile apps performance testing. What matters is a commitment to a strategic testing plan that tailor’s app functions to user needs. Specifically, your mobile apps performance testing plan should effectively meet user needs and deliver excellent value to them. Only then are the rewards of mobile app performance testing worth the efforts involved.
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