Kakao 2022 New Hire Android Onboarding Retrospective: Learning Clean Architecture and DI

Kakao's 2022 new hires (New Crew) reflected on their 6-week Android technology onboarding process. The onboarding focused on Clean Architecture and Dependency Injection (DI), with the following key assignments:

1. To Do App (Weeks 1–2): Utilized ListView, RecyclerView, ViewModel, and LiveData, separating Presentation, Data, and Domain layers according to Clean Architecture. Implemented data persistence using Room DB.
2. Note App (Week 3): Introduced Use Cases to separate logic from ViewModels and wrote Unit Tests and Android Tests to improve code quality.
3. Network Communication (Week 4): Fetched server data and implemented pagination using HTTP communication and the Paging 3 library.
4. if(kakao) 2021 Website Implementation (Weeks 5–6): Reproduced the if(kakao) 2021 website as an Android app. Designed a native UX using DrawerLayout and ViewPager, resolving issues such as ViewPager height problems.

DI Adoption and TDD Attempt Initially, the team faced code duplication and dependency issues due to manual dependency injection. They adopted DI tools like Hilt and Koin to reduce coupling and facilitate unit testing. Additionally, some crew members attempted TDD (Test-Driven Development), but encountered side effects such as increased workload and higher modification costs due to writing test code and refactoring, which slowed down development speed. Consequently, they halted TDD adoption and returned to a Unit Test-centric approach, recording this process itself as a valuable experience in exploring new programming methodologies.