oneway-reducer-management

name	oneway-reducer-management
description	Guides the creation and testing of Reducers and Stores using the OneWay library and Clean Architecture in the Badabook project. Use this skill when implementing new features or fixing bugs in the App layer that involve state management.

OneWay Reducer Management

This skill provides standardized patterns for implementing and testing Reducers using the OneWay library within the Badabook project's Clean Architecture.

Core Concepts

• State: A thread-safe, immutable data model representing the UI state.
• Action: A set of user intentions or external events that trigger state changes or side effects.
• Reducer: A pure logic component that transitions the state based on actions and manages side effects via AnyEffect.
• Store: The container that holds the state and processes actions.

Workflows

1. Implementing a New Reducer

Follow the patterns in reducer-pattern.md to:

1. Define the Action enum (Sendable).
2. Define the State struct (Equatable, Sendable).
3. Declare dependencies using the @UseCase property wrapper.
4. Implement the reduce(state:action:) method.
5. (Optional) Implement the bind() method for long-running effects.
6. Create private execute...UseCase helpers for async operations.

2. Testing a Reducer

Follow the patterns in test-pattern.md to:

1. Use @Suite and @Test from Swift Testing.
2. Initialize dependencies using UseCaseContainer.instance.register.
3. Create a Store instance with the reducer and initial state.
4. Use await sut.send(action) to trigger actions.
5. Use await sut.expect(\.property, value) to verify state transitions.
6. Use UseCaseContainer.$instance.withValue for scoped dependency injection in tests.

Key Principles

• Surgical State Changes: Only update the necessary properties in reduce.
• Async Safety: Use .single or .sequence effects for asynchronous tasks.
• Dependency Injection: Always use @UseCase and UseCaseContainer to ensure testability.
• Unidirectional Flow: Actions flow into the Store, and state updates flow out.