Clean Architecture layers in Flutter - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify the correct Clean Architecture layer for UI code

In Flutter Clean Architecture, where should you place your widgets and UI code?

A In the Presentation layer

B In the Domain layer

C In the Data layer

D In the Infrastructure layer

💡 Hint

Think about where the user sees and interacts with the app.

The Presentation layer contains UI code like widgets because it handles what the user sees and interacts with.

🧠 Conceptual

intermediate

Role of the Domain layer in Clean Architecture

What is the main responsibility of the Domain layer in Clean Architecture for Flutter apps?

A Managing UI state and widgets

B Handling business rules and use cases

C Fetching data from APIs or databases

D Implementing platform-specific code

💡 Hint

This layer contains the core logic that does not depend on UI or data sources.

The Domain layer holds business rules and use cases, making it independent from UI and data layers.

❓ ui_behavior

advanced

Effect of mixing Data layer code in Presentation layer

What happens if you put API calls directly inside Flutter widgets in the Presentation layer?

A The app runs faster because data is fetched directly in UI

B The app will crash due to missing dependencies

C The Domain layer automatically handles the API calls

D The app becomes harder to maintain and test because UI and data logic are mixed

💡 Hint

Consider separation of concerns and testability.

Mixing API calls in UI code breaks separation of concerns, making the app harder to maintain and test.

❓ lifecycle

advanced

Dependency direction in Clean Architecture

In Clean Architecture, which direction should dependencies flow between layers?

A Only between Presentation and Data layers, skipping Domain

B From Domain layer outward to Data and Presentation layers

C From outer layers (Presentation, Data) inward to Domain layer

D Between layers in both directions freely

💡 Hint

Think about which layer is the core and should not depend on others.

Dependencies flow inward toward the Domain layer, which is independent and core to the app.

🔧 Debug

expert

Identifying layer violation causing test failure

You wrote a unit test for a Domain use case but it fails because it tries to access Flutter widgets. What is the likely cause?

A The Domain layer code is incorrectly importing Presentation layer widgets

B The Data layer is missing API implementation

C The Domain layer is missing dependency injection

D The Presentation layer is not initialized

💡 Hint

Domain layer should not depend on UI code.

Domain layer must be independent of UI. Importing widgets there breaks this and causes test failures.