Context

When adding a mobile feature in an existing codebase, strong test design matters as much as the implementation. Interviewers want to see that you can add confidence quickly without over-testing low-value paths.

Core Question

Explain how you would think about writing tests for a new mobile feature while pairing in an existing codebase.

Address these points:

1. How do you decide what to test first when the codebase already has patterns and constraints?
2. How do you choose between unit, integration, and UI/end-to-end tests for the feature?
3. How do you handle dependencies such as network calls, local storage, feature flags, and asynchronous behavior?

Scope Guidance

Focus on a practical engineering approach rather than a specific test framework. The interviewer expects a structured explanation of risk-based coverage, test boundaries, maintainability, and how you would learn existing conventions before adding new tests.