Better Android Testing at Airbnb (Part 4)
Article Summary
Airbnb's Android tests were failing randomly. The culprit? Everything from cached drawables to delayed runnables creating unpredictable test behavior.
In Part 6 of their testing series, Airbnb's Eli Hart reveals the hidden sources of test flakiness that plague screenshot and interaction testing. With tests running in unpredictable order via Flank, even small state leaks compound into major reliability issues.
Key Takeaways
- Forced drawable cache clearing after each screenshot eliminated pixel variation flakiness
- Custom wrapper functions for postDelay and async code enable deterministic test execution
- Mocked date framework ensures JodaTime calls return consistent values across test runs
- Disabled RecyclerView prefetching prevents non-deterministic view layout during screenshots
- Centralized ImageView architecture allows synchronous local asset injection instead of network loads
Critical Insight
Airbnb achieved reliable Android testing by systematically eliminating flakiness sources at the framework level, from shared preferences to WebView mocking.
