Improve Android Testability with Fakes and Factories
Article Summary
Brian Plummer from OkCupid hit a wall adding a simple analytics event: his unit tests broke because static constructs were calling the analytics library directly. Here's how he fixed it with a pattern that made the code more testable.
OkCupid's engineering team faced a common legacy code problem: tightly coupled analytics that broke tests. The existing pattern had ViewModels calling analytics directly through static objects, making unit testing impossible without invoking the actual analytics SDK in the JVM.
Key Takeaways
- Introduced interfaces to decouple ViewModels from concrete analytics implementations
- Created fakes with boolean flags to verify events fired without calling real SDKs
- Extracted processing logic into data class factories for isolated testing
- Reduced ViewModel responsibility by moving event creation to companion objects
Critical Insight
By abstracting analytics behind interfaces and using fakes instead of mocks, the team made their ViewModels testable while keeping event processing logic verifiable in isolation.
