Debugging is a crucial part of testing mobile apps. Bugs and crashes need to be diagnosed and fixed before an app can be released. Mobile app debugging requires some specialized tools and techniques. In this guide, we’ll walk through a systematic debugging process to efficiently find and fix issues in mobile apps.
Testing and debugging are intricately connected stages within the application development lifecycle, as they both play crucial roles in pinpointing and rectifying issues within a mobile application. Despite having separate objectives and tasks, they frequently intersect and reinforce one another.
Testing serves as a cornerstone in guaranteeing quality assurance, compatibility, reliability, security, performance enhancement, usability, and iterative refinement. These fundamental facets of application development are instrumental in ensuring that an application adheres to rigorous standards and operates seamlessly across diverse scenarios, thereby enhancing user experience and satisfaction, adhering to regulatory requirements, and bolstering the business’s reputation.
What is debugging a mobile app?
Debugging a mobile app refers to the process of identifying, reproducing, and fixing bugs and issues in a mobile application. It involves using various mobile app testing tools and techniques to examine the application’s code, interface, performance, network communications, and internal state during execution to find problems and errors.
Using debug builds and simulators to consistently recreate issues encountered during testing or by users. Taking detailed bug reports and logs helps reproduce errors for debugging. Connecting the mobile device to a debugger to step through code execution and analyze values. Logging prints and breakpoints also helps trace the execution flow and spot problems. Debugging on emulators that simulate real devices allows testing a wide range of device configurations.
Prepare for Debugging
First, some upfront steps to enable effective debugging:
- Enable developer options on the test device – This unlocks debugging features in the OS.
- Install the platform debugger – Android Studio debugger for Android apps or Xcode debugger for iOS apps.
- Enable USB debugging on the device to connect it to the debugger.
- Set up exception breakpoints in the debugger to pause execution when crashes happen.
- Understand the app architecture and environment – OS, device, network, etc.
With the prerequisites in place, we can move on to techniques of debugging mobile apps.
Reproduce the Crash
The first step is reproducing the exact way the app crashes or malfunctions. Note down all the steps leading up to the crash and details of the state of the app. Try to reproduce it on a regular basis. This crash log will be vital for diagnosing the issue.
Isolate the Cause
Once the bug can be reliably reproduced, we need to isolate where exactly things are going wrong. Use the debugger or add strategic logging statements to understand the flow. Go step-by-step to find the line of code or sequence of events leading to the failure. Isolating the origin of the problem is crucial before fixing it.
Debug the Functionality
For functional bugs or incorrect behaviors, use the debugger or logging to trace the code paths associated with that functionality. Set up test data to analyze how the actual behavior diverges from the expected. Check values of key variables to pinpoint bugs in business logic or calculations. Break down complex processes into smaller, debuggable components.
Check Performance Issues
For performance issues like slow loading times, the debugger and device logs can help uncover bottlenecks. Profile CPU, memory, and network usage during the affected flows to identify spikes. Check for blocked threads, excessive processing, or network requests. A mobile app testing tool with real devices can model real world loads to diagnose performance problems.
Analyze Crashes and Exceptions
When the app crashes, the debugger stack trace and device crash logs provide clues on the exception. For native crashes, symbolicate the crash dump to demangle symbols. Examine the exception type, error messages and stack frames leading up to it. Look for bad state, unexpected nulls, invalid data, etc. that caused the exception.
Check Edge Cases
Often, bugs manifest in edge cases that are not regularly tested. Make sure to debug scenarios like low memory, network failures, sudden terminations, etc. Test on a variety of supported OS versions and device configurations to catch bugs. Stress test boundary conditions and simulate unreliable networks during debugging.
Debug Memory Issues
Memory issues like leaks or block corruption can be notoriously hard to debug. Use memory profiling tools to check for spikes in memory allocation and monitor for leaks. Debugging with guard malloc can help catch overruns. Enable address sanitizers to detect heap corruption. In the worst-case scenario, a memory debugger helps debug complex memory bugs.
Debug Cross-Platform Issues
For apps targeting multiple platforms, subtle differences in OS behavior can cause bugs. Debug across multiple devices and OS versions, watching for platform-specific issues. Create consistency in handling dates, encodings, locales, etc. Check for OS-based feature detection. Automate parallel testing across platforms to efficiently catch multi-platform bugs.
Debug Intermittent Issues
Bugs that come and go randomly are tricky to diagnose. Add more logging to narrow down the conditions triggering the issue. Analyze logs from past occurrences for clues. Persist in the application state frequently to investigate prior unstable states. Gather as much runtime data as possible to reconstruct intermittent issues.
Inspect Third-Party Code
Bugs in third party libraries need a different approach. Isolate the buggy behavior to the external code. Debug within the library constraints by hooking APIs or reverse engineering. Check for problems calling into the library, like invalid arguments or sequencing issues. Wrapping problematic interfaces can aid in debugging.
Field Debugging Techniques
Once the app is live, debug user-reported issues through crash reports, telemetry and logs. Reproduce problems using debug builds, virtual devices and emulators. Support diagnostic features like on-device logging for beta testers. Analyze real user workflows and behaviors to fix field bugs.
Final Note
In conclusion, debugging mobile apps leverages specialized tools and techniques to inspect functionality, analyze crashes, and fix bugs. Methodically isolating issues, profiling performance, stress testing edge cases, and debugging in production are key to stamping out mobile app bugs and delivering robust apps.