Compatibility testing
An application rarely runs in just one environment once it's released. It might run on Windows, macOS, or Linux, on a range of hardware with different amounts of memory or processing power, alongside different versions of a dependency or runtime, or over a flaky mobile network instead of a fast, stable office connection. Compatibility testing checks that behavior holds up across that real variety, not just the specific, often well-resourced environment where development and initial testing happened.
A few specific forms cover most of this work. Operating system compatibility checks whether an app behaves the same on Windows, macOS, Linux, or across different mobile OS versions. Hardware compatibility covers different screen sizes, resolutions, processing power, and memory constraints. Software and dependency compatibility confirms the app still works with an older or newer version of a database, a library, or another integrated system. Network compatibility checks whether it holds up over a slow or unreliable connection, not just a fast one. Cross browser testing is the most familiar specific instance of this for web applications, checking behavior across different browser engines and versions.
Teams generally approach this the same way they approach cross browser testing, prioritizing based on real usage data rather than testing every theoretically possible combination, and running against actual target environments, real devices, real OS versions, real network conditions, where practical, rather than only simulating them, since some compatibility issues only show up on real hardware or a real, imperfect network.
Specific forms
- Operating system compatibility, checking behavior across Windows, macOS, Linux, or different mobile OS versions.
- Hardware compatibility, covering different screen sizes, resolutions, processing power, and memory constraints.
- Software and dependency compatibility, confirming the app still works with an older or newer version of a database, library, or integrated system.
- Network compatibility, checking behavior over a slow or unreliable connection, not just a fast, stable one.
- Cross browser testing, the most familiar specific instance for web applications, checking behavior across different browser engines.
Where it shows up
- Checking that a mobile app behaves correctly across several versions of iOS and Android, not just the newest release.
- Confirming an application still works after a dependency, like a database version, gets upgraded elsewhere in the stack.
- Testing how an app performs for a user on a slow, unreliable mobile network instead of a fast office connection.
- Verifying a desktop application runs consistently across Windows, macOS, and Linux where it's meant to support all three.
Benefits and challenges
| Benefit | Challenge |
|---|---|
| Catches a problem that only appears in an environment different from the one development and initial testing actually happened in. | The full matrix of environments, OS, hardware, software versions, network conditions, is large, testing every combination isn't realistic. |
| Confirms an application actually works for the real variety of conditions users have, not just an ideal, well-resourced setup. | Some compatibility issues only show up on real hardware or a real network, simulation alone doesn't always catch them. |
| Prioritizing based on real usage data keeps the effort focused on environments that actually matter, rather than theoretical completeness. | Usage data changes over time, a combination that was negligible last year might matter a lot more now. |
Frequently asked questions
How is compatibility testing different from cross browser testing?
Cross browser testing is one specific kind of compatibility testing, focused on how a web application behaves across different browser engines and versions. Compatibility testing is the broader category, also covering operating systems, hardware, dependency versions, and network conditions, well beyond just the browser.
How do teams decide which environments to test?
Most prioritize based on real usage data, which operating systems, devices, and browser versions actual users are on, rather than trying to cover every theoretically possible combination. Anything below a small usage threshold is typically treated as lower priority rather than untested by policy.
Does compatibility testing need real hardware, or is simulation enough?
Simulation and emulation cover a lot of ground efficiently, but some issues, timing quirks, real network conditions, actual device performance, only show up on real hardware. Many teams use simulation for broad coverage and real devices for the combinations that matter most.
How Klarent helps
Klarent's AI agents run generated tests across the browser and device combinations that matter most for an application, recognizing an element by what it does rather than a fixed selector that might resolve differently between environments.