Composable Architecture

https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture
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### Constructing a NavigationLinkStore

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationlinkstore

Example of initializing a NavigationLinkStore using a scoped store focused on the presentation domain.

```swift
NavigationLinkStore(
  self.store.scope(state: \.$child, action: { .child($0) })
) {
  viewStore.send(.linkTapped)
} destination: { store in
  ChildView(store: store)
} label: {
  Text("Go to child")
}
```

--------------------------------

### Usage of binding(get:send:) with TextField

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/binding%28get%3Asend%3A%29-65xes

Example showing how to bind a TextField to store state using a getter and an action creator.

```swift
struct State { var name = "" }
enum Action { case nameChanged(String) }


TextField(
  "Enter name",
  text: viewStore.binding(
    get: { $0.name },
    send: { Action.nameChanged($0) }
  )
)
```

--------------------------------

### Declaration of starts(with:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/stackstate/starts%28with%3A%29

The method signature for starts(with:) as defined in the Sequence protocol.

```swift
func starts<PossiblePrefix>(with possiblePrefix: PossiblePrefix) -> Bool where PossiblePrefix : Sequence, Self.Element == PossiblePrefix.Element
```

--------------------------------

### Transforming all dependencies

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/bindingreducer/transformdependency%28_%3Atransform%3A%29

Example of using the \.self key path to access and transform all dependency values at once.

```swift
Feature()
  .transformDependency(\.self) { dependencyValues in
    // Access to all dependencies in here
  }
```

--------------------------------

### Feature Reducer Implementation

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/send%28_%3Awhile%3A%29

A reducer example demonstrating how to track loading state to support the send(_:while:) method.

```swift
struct Feature: Reducer {
  struct State: Equatable {
    var isLoading = false
    var response: String?
  }
  enum Action {
    case pulledToRefresh
    case receivedResponse(TaskResult<String>)
  }
  @Dependency(\.fetch) var fetch


  func reduce(into state: inout State, action: Action) -> Effect<Action> {
    switch action {
    case .pulledToRefresh:
      state.isLoading = true
      return .run { send in
        await send(.receivedResponse(TaskResult { try await self.fetch() }))
      }


    case let .receivedResponse(result):
      state.isLoading = false
      state.response = try? result.value
      return .none
    }
  }
}
```

--------------------------------

### Using binding(get:send:) with an alert

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/binding%28get%3Asend%3A%29-l66r

Example showing how to bind an alert item to a view store state property.

```swift

struct State { var alert: String? }
enum Action { case alertDismissed }


.alert(
  item: viewStore.binding(
    get: { $0.alert },
    send: .alertDismissed
  )
) { alert in Alert(title: Text(alert.message)) }
```

--------------------------------

### Registering a dependency

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/swiftconcurrency

Example of extending DependencyValues to provide a custom dependency.

```swift
extension DependencyValues {
  var factClient: FactClient {
    get { self[FactClient.self] }
    set { self[FactClient.self] = newValue }
  }
}
```

--------------------------------

### Declaration of starts(with:by:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/stackstate/starts%28with%3Aby%3A%29

The method signature for checking sequence prefixes with a custom closure.

```swift
func starts<PossiblePrefix>(
    with possiblePrefix: PossiblePrefix,
    by areEquivalent: (Self.Element, PossiblePrefix.Element) throws -> Bool
) rethrows -> Bool where PossiblePrefix : Sequence
```

--------------------------------

### Onboarding Reducer Structure

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/bindingreducer/dependency%28_%3A_%3A%29

An example of a reducer structure that embeds a feature and additional onboarding logic.

```swift
struct Onboarding: Reducer {
  struct State {
    var feature: Feature.State
    // Additional onboarding state
  }
  enum Action {
    case feature(Feature.Action)
    // Additional onboarding actions
  }


  var body: some Reducer<State, Action> {
    Scope(state: \.feature, action: /Action.feature) {
      Feature()
    }


    Reduce { state, action in
      // Additional onboarding logic
    }
  }
}
```

--------------------------------

### Example usage of receive with predicate

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore/receive%28_%3Atimeout%3Aassert%3Afile%3Aline%3A%29-7md3m

Demonstrates using a predicate to match a specific action case and asserting the resulting state change.

```swift
await store.send(.buttonTapped)
await store.receive {
  guard case .response(.success) = $0 else { return false }
  return true
} assert: {
  store.count = 42
}
```

--------------------------------

### Initialize the App Store

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/gettingstarted

Constructs the store at the application entry point by providing initial state and the reducer.

```swift
@main
struct MyApp: App {
  var body: some Scene {
    FeatureView(
      store: Store(initialState: Feature.State()) {
        Feature()
      }
    )
  }
}
```

--------------------------------

### Asserting an action and state change

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore/receive%28_%3Atimeout%3Aassert%3Afile%3Aline%3A%29-5vi0x

Example usage of the receive method to verify an action and update state.

```swift
await store.send(.buttonTapped)
await store.receive(.response(.success(42)) {
  $0.count = 42
}
```

--------------------------------

### init(Store<StackState<State>, StackAction<State, Action>>, root: () -> Root, destination: (Store<State, Action>) -> Destination)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationstackstore

Creates a navigation stack with a store of stack state and actions, using a closure that provides a store to the destination view.

```APIDOC
## init(Store<StackState<State>, StackAction<State, Action>>, root: () -> Root, destination: (Store<State, Action>) -> Destination)

### Description
Creates a navigation stack with a store of stack state and actions. This initializer uses a closure that provides a store to the destination view.

### Parameters
- **store** (Store<StackState<State>, StackAction<State, Action>>) - The store focused on stack state and actions.
- **root** (() -> Root) - A closure that returns the root view of the navigation stack.
- **destination** ((Store<State, Action>) -> Destination) - A closure that provides a store to the destination view.
```

--------------------------------

### init(_:content:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/switchstore/init%28_%3Acontent%3A%29

Initializes a SwitchStore with a store and a view builder closure that transforms the state into content.

```APIDOC
## init(_:content:)

### Declaration
`init(_ store: Store<State, Action>, @ViewBuilder content: @escaping (State) -> Content)`

### Description
Initializes a new SwitchStore instance. It observes the provided store and uses the content closure to render views based on the current state.
```

--------------------------------

### TestStore Failure Example

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore

Example of an incorrect state assertion that triggers a test failure.

```swift
await store.send(.incrementButtonTapped) {
  $0.count = 42
}
```

--------------------------------

### init(_:state:action:onTap:destination:label:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationlinkstore/init%28_%3Astate%3Aaction%3Aontap%3Adestination%3Alabel%3A%29

Initializes a NavigationLinkStore with a store, state transformation, action transformation, tap handler, destination view builder, and label builder.

```APIDOC
## init(_:state:action:onTap:destination:label:)

### Declaration
```swift
init(
    _ store: Store<PresentationState<State>, PresentationAction<Action>>,
    state toDestinationState: @escaping (State) -> DestinationState?,
    action fromDestinationAction: @escaping (DestinationAction) -> Action,
    onTap: @escaping () -> Void, 
    @ViewBuilder destination: @escaping (Store<DestinationState, DestinationAction>) -> Destination, 
    @ViewBuilder label: () -> Label
)
```

### Availability
- iOS 13.0–16.0 (Deprecated)
- macOS 10.15–13.0 (Deprecated)
- tvOS 13.0–16.0 (Deprecated)
- watchOS 6.0–9.0 (Deprecated)
```

--------------------------------

### init<State>(_:observe:content:file:line:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withviewstore/init%28_%3Aobserve%3Acontent%3Afile%3Aline%3A%29-8g15l

Initializes a WithViewStore to observe state changes and compute views. Available when ViewState conforms to Equatable and Content conforms to View.

```APIDOC
## init(_:observe:content:file:line:)

### Description
Initializes a structure that transforms a `Store` into an observable `ViewStore` in order to compute views from state. This allows for performance optimization by observing only necessary slices of state.

### Signature
```swift
init<State>(
    _ store: Store<State, ViewAction>,
    observe toViewState: @escaping (State) -> ViewState, 
    @ViewBuilder content: @escaping (ViewStore<ViewState, ViewAction>) -> Content,
    file: StaticString = #fileID,
    line: UInt = #line
)
```

### Parameters
- **store** (Store<State, ViewAction>) - The store to observe.
- **toViewState** ((State) -> ViewState) - A function that transforms store state into observable view state. Changes to this view state trigger view re-computation.
- **content** ((ViewStore<ViewState, ViewAction>) -> Content) - A function that generates content from the view store.
- **file** (StaticString) - Optional. The file identifier for debugging.
- **line** (UInt) - Optional. The line number for debugging.
```

--------------------------------

### Exhaustive integration test example

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore

An example of an exhaustive test flow for a login feature, requiring assertions on every state change and effect.

```swift
let store = TestStore(initialState: App.State()) {
  App()
}


// 1️⃣ Emulate user tapping on submit button.
await store.send(.login(.submitButtonTapped)) {
  // 2️⃣ Assert how all state changes in the login feature
  $0.login?.isLoading = true
  …
}


// 3️⃣ Login feature performs API request to login, and
//    sends response back into system.
await store.receive(.login(.loginResponse(.success))) {
// 4️⃣ Assert how all state changes in the login feature
  $0.login?.isLoading = false
  …
}


// 5️⃣ Login feature sends a delegate action to let parent
//    feature know it has successfully logged in.
await store.receive(.login(.delegate(.didLogin))) {
// 6️⃣ Assert how all of app state changes due to that action.
  $0.authenticatedTab = .loggedIn(
    Profile.State(...)
  )
  …
  // 7️⃣ *Finally* assert that the selected tab switches to activity.
  $0.selectedTab = .activity
}
```

--------------------------------

### init(initialState:reducer:withDependencies:file:line:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore/init%28initialstate%3Areducer%3Awithdependencies%3Afile%3Aline%3A%29-3zio1

Initializes a new TestStore instance with the provided state, reducer, and dependency overrides.

```APIDOC
## init(initialState:reducer:withDependencies:file:line:)

### Description
Creates a test store with an initial state and a reducer powering its runtime. This is used to test features in the Composable Architecture.

### Declaration
```swift
init<R>(
    initialState: @autoclosure () -> R.State, @ReducerBuilder<State, Action> reducer: () -> R,
    withDependencies prepareDependencies: (inout DependencyValues) -> Void = { _ in
    },
    file: StaticString = #file,
    line: UInt = #line
) where State : Equatable, State == R.State, Action == R.Action, R : Reducer
```

### Parameters
- **initialState** (autoclosure) - The state the feature starts in.
- **reducer** (ReducerBuilder) - The reducer that powers the runtime of the feature.
- **prepareDependencies** (closure) - A closure that can be used to override dependencies that will be accessed during the test.
```

--------------------------------

### trimPrefix(while:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/stackstate/trimprefix%28while%3A%29

Removes elements from the start of the collection that satisfy the provided predicate.

```APIDOC
## trimPrefix(while:)

### Description
Removes elements from the beginning of the collection as long as they satisfy the given predicate.

### Declaration
`mutating func trimPrefix(while predicate: (Self.Element) throws -> Bool) rethrows`

### Availability
- iOS 16.0+
- macOS 13.0+
- tvOS 16.0+
- watchOS 9.0+
```

--------------------------------

### Using ifLet for Navigation in UIKit

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/store/iflet%28then%3Aelse%3A%29

Example demonstrating how to use ifLet to manage navigation stack updates based on optional child state changes.

```swift
class ParentViewController: UIViewController {
  let store: Store<ParentState, ParentAction>
  var cancellables: Set<AnyCancellable> = []
  // ...
  func viewDidLoad() {
    // ...
    self.store
      .scope(state: \.optionalChild, action: ParentAction.child)
      .ifLet(
        then: { [weak self] childStore in
          self?.navigationController?.pushViewController(
            ChildViewController(store: childStore),
            animated: true
          )
        },
        else: { [weak self] in
          guard let self = self else { return }
          self.navigationController?.popToViewController(self, animated: true)
        }
      )
      .store(in: &self.cancellables)
  }
}
```

--------------------------------

### Using binding(send:) with TextField

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/binding%28send%3A%29-7nwak

Example of creating a binding for a TextField that dispatches a nameChanged action when the text input changes.

```swift
typealias State = String
enum Action { case nameChanged(String) }


TextField(
  "Enter name",
  text: viewStore.binding(
    send: { Action.nameChanged($0) }
  )
)
```

--------------------------------

### init(_:root:destination:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationstackstore/init%28_%3Aroot%3Adestination%3A%29-f5dc

Initializes a navigation stack with a store of stack state and actions, a root view, and a destination view builder.

```APIDOC
## init(_:root:destination:)

### Description
Creates a navigation stack with a store of stack state and actions.

### Declaration
`init(_ store: Store<StackState<State>, StackAction<State, Action>>, @ViewBuilder root: () -> Root, @ViewBuilder destination: @escaping (Store<State, Action>) -> Destination)`

### Parameters
- **store** (Store<StackState<State>, StackAction<State, Action>>) - A store of stack state and actions to power this stack.
- **root** (() -> Root) - The view to display when the stack is empty.
- **destination** ((Store<State, Action>) -> Destination) - A view builder that defines a view to display when an element is appended to the stack’s state. The closure takes one argument, which is a store of the value to present.
```

--------------------------------

### WithViewStore Initializers

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withviewstore/init%28_%3Aobserve%3Acontent%3Afile%3Aline%3A%29-8g15l

Initializers for creating a WithViewStore instance to observe state and compute views.

```APIDOC
## WithViewStore Initializers

### Description
These initializers transform a `Store` into an observable `ViewStore` to compute views from state. They support various configurations including state observation, action mapping, binding support, and duplicate removal.

### Signatures
- `init<State>(Store<State, ViewAction>, observe: (State) -> ViewState, removeDuplicates: (ViewState, ViewState) -> Bool, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
- `init<State, Action>(Store<State, Action>, observe: (State) -> ViewState, send: (ViewAction) -> Action, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
- `init<State, Action>(Store<State, Action>, observe: (State) -> ViewState, send: (ViewAction) -> Action, removeDuplicates: (ViewState, ViewState) -> Bool, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
- `init<State>(Store<State, ViewAction>, observe: (BindingViewStore<State>) -> ViewState, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
- `init<State>(Store<State, ViewAction>, observe: (BindingViewStore<State>) -> ViewState, removeDuplicates: (ViewState, ViewState) -> Bool, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
- `init<State, Action>(Store<State, Action>, observe: (BindingViewStore<State>) -> ViewState, send: (ViewAction) -> Action, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
- `init<State, Action>(Store<State, Action>, observe: (BindingViewStore<State>) -> ViewState, send: (ViewAction) -> Action, removeDuplicates: (ViewState, ViewState) -> Bool, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)`
```

--------------------------------

### Parent Reducer Implementation

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/bindingreducer/foreach%28_%3Aaction%3Aelement%3Afileid%3Aline%3A%29

Example of using forEach to integrate a child reducer into a parent feature's state and action domain.

```swift
struct Parent: Reducer {
  struct State {
    var rows: IdentifiedArrayOf<Row.State>
    // ...
  }
  enum Action {
    case row(id: Row.State.ID, action: Row.Action)
    // ...
  }


  var body: some Reducer<State, Action> {
    Reduce { state, action in
      // Core logic for parent feature
    }
    .forEach(\.rows, action: /Action.row) {
      Row()
    }
  }
}
```

--------------------------------

### Counter Reducer Implementation

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore

A simple counter reducer used for testing examples.

```swift
struct Counter: Reducer {
  struct State: Equatable {
    var count = 0
  }


  enum Action {
    case decrementButtonTapped
    case incrementButtonTapped
  }


  func reduce(
    into state: inout State, action: Action
  ) -> Effect<Action> {
    switch action {
    case .decrementButtonTapped:
      state.count -= 1
      return .none


    case .incrementButtonTapped:
      state.count += 1
      return .none
    }
  }
}
```

--------------------------------

### init(initialState:reducer:withDependencies:file:line:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore/init%28initialstate%3Areducer%3Awithdependencies%3Afile%3Aline%3A%29-8f79s

Initializes a new TestStore instance with the specified state, reducer, and dependency overrides.

```APIDOC
## init(initialState:reducer:withDependencies:file:line:)

### Description
Creates a test store with an initial state and a reducer powering its runtime.

### Signature
```swift
init<R>(
    initialState: @autoclosure () -> R.State, 
    @ReducerBuilder<State, Action> reducer: () -> R,
    withDependencies prepareDependencies: (inout DependencyValues) -> Void = { _ in },
    file: StaticString = #file,
    line: UInt = #line
) where State == R.State, Action == R.Action, R : Reducer
```

### Parameters
- **initialState** (@autoclosure () -> R.State) - The state the feature starts in.
- **reducer** (() -> R) - The reducer that powers the runtime of the feature.
- **prepareDependencies** ((inout DependencyValues) -> Void) - Optional. A closure that can be used to override dependencies that will be accessed during the test.
```

--------------------------------

### Basic usage of withTaskCancellation

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withtaskcancellation%28id%3Acancelinflight%3Aoperation%3A%29

Example showing how to wrap an operation with a cancellation identifier.

```swift
enum CancelID { case timer }


await withTaskCancellation(id: CancelID.timer) {
  // Start cancellable timer...
}
```

--------------------------------

### init(initialState:reducer:withDependencies:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/store

Initializes a store from an initial state and a reducer.

```APIDOC
## init(initialState:reducer:withDependencies:)

### Description
Initializes a store from an initial state and a reducer.

### Signature
`convenience init<R>(initialState: () -> R.State, reducer: () -> R, withDependencies: ((inout DependencyValues) -> Void)?)`
```

--------------------------------

### Define Todo Reducer

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/foreachstore

Example of a reducer domain for an individual todo item.

```swift
struct Todo: Reducer {
  struct State: Equatable, Identifiable {
    let id: UUID
    var description = ""
    var isComplete = false
  }


  enum Action {
    case isCompleteToggled(Bool)
    case descriptionChanged(String)
  }


  func reduce(into state: inout State, action: Action) -> Effect<Action> {
    // ...
  }
}
```

--------------------------------

### Declaration of binding(get:send:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/binding%28get%3Asend%3A%29-l66r

The method signature for creating a binding from a ViewStore.

```swift
func binding<Value>(
    get: @escaping (ViewState) -> Value,
    send action: ViewAction
) -> Binding<Value>
```

--------------------------------

### init<D>(Store<StackState<State>, StackAction<State, Action>>, root: () -> Root, destination: (State) -> D)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationstackstore

Creates a navigation stack with a store of stack state and actions, using a closure to transform state into a destination view.

```APIDOC
## init<D>(Store<StackState<State>, StackAction<State, Action>>, root: () -> Root, destination: (State) -> D)

### Description
Creates a navigation stack with a store of stack state and actions. This initializer uses a closure that transforms state into a destination view.

### Parameters
- **store** (Store<StackState<State>, StackAction<State, Action>>) - The store focused on stack state and actions.
- **root** (() -> Root) - A closure that returns the root view of the navigation stack.
- **destination** ((State) -> D) - A closure that transforms state into a destination view.
```

--------------------------------

### init(_:content:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/foreachstore/init%28_%3Acontent%3A%29

Initializes a structure that computes views on demand from a store on a collection of data and an identified action.

```APIDOC
## init(_:content:)

### Description
Initializes a structure that computes views on demand from a store on a collection of data and an identified action.

### Declaration
`init<EachContent>(_ store: Store<IdentifiedArray<ID, EachState>, (ID, EachAction)>, @ViewBuilder content: @escaping (Store<EachState, EachAction>) -> EachContent) where Data == IdentifiedArray<ID, EachState>, Content == WithViewStore<IdentifiedArray<ID, EachState>, (ID, EachAction), ForEach<IdentifiedArray<ID, EachState>, ID, EachContent>>, EachContent : View`

### Parameters
- **store** (Store<IdentifiedArray<ID, EachState>, (ID, EachAction)>) - A store on an identified array of data and an identified action.
- **content** ((Store<EachState, EachAction>) -> EachContent) - A function that can generate content given a store of an element.
```

--------------------------------

### Declaration of startIndex

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/stackstate/startindex

The property is defined as a read-only integer representing the start index of the collection.

```swift
var startIndex: Int { get }
```

--------------------------------

### TaskResult in Action

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/taskresult

Example of using TaskResult as a payload within an Equatable action enum.

```swift
enum Action: Equatable {
  case factButtonTapped
  case factResponse(TaskResult<String>)
}
```

--------------------------------

### init(_:observe:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/init%28_%3Aobserve%3A%29-3ak1y

Initializes a view store from a store which observes changes to state.

```APIDOC
## init(_:observe:)

### Description
Initializes a view store from a store which observes changes to state. This initializer is available when `ViewState` conforms to `Equatable`.

### Declaration
```swift
convenience init<State>(
    _ store: Store<State, ViewAction>,
    observe toViewState: @escaping (State) -> ViewState
)
```

### Parameters
- **store** (Store<State, ViewAction>) - A store.
- **toViewState** ((State) -> ViewState) - A transformation of `ViewState` to the state that will be observed for changes.

### Discussion
It is recommended that the `observe` argument transform the store’s state into the bare minimum of data needed for the feature to do its job in order to not hinder performance.
```

--------------------------------

### Configure TestStore with Dependencies

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/gettingstarted

Shows how to instantiate a TestStore and override specific dependencies for testing purposes.

```swift
let store = TestStore(initialState: Feature.State()) {
  Feature()
} withDependencies: {
  $0.numberFact.fetch = { "\($0) is a good number Brent" }
}


await store.send(.numberFactButtonTapped)
await store.receive(.numberFactResponse("0 is a good number Brent")) {
  $0.numberFactAlert = "0 is a good number Brent"
}
```

--------------------------------

### EventsClient definition

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/effect/run%28priority%3Aoperation%3Acatch%3Afileid%3Aline%3A%29

Example structure for a dependency client providing an async stream of events.

```swift
struct EventsClient {
  var events: () -> AsyncStream<Event>
}
```

--------------------------------

### Applying animation to an Effect

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/effect/animation%28_%3A%29

Example of chaining the animation method to an effect returned by a reducer.

```swift
case .buttonTapped:
  return .run { send in
    await send(.activityResponse(self.apiClient.fetchActivity()))
  }
  .animation()
```

--------------------------------

### init(_:observe:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/init%28_%3Aobserve%3A%29-96hm5

Initializes a ViewStore that transforms a Store into an observable state container for SwiftUI bindings.

```APIDOC
## init(_:observe:)

### Description
Initializes a structure that transforms a `Store` into an observable `ViewStore` in order to compute bindings from state.

### Declaration
```swift
convenience init<State>(
    _ store: Store<State, ViewAction>,
    observe toViewState: @escaping (BindingViewStore<State>) -> ViewState
) where ViewAction : BindableAction, State == ViewAction.State
```

### Parameters
- **store** (Store<State, ViewAction>) - A store.
- **toViewState** ((BindingViewStore<State>) -> ViewState) - A function that transforms binding store state into observable view state. All changes to the view state will cause the `WithViewStore` to re-compute its view.
```

--------------------------------

### init(_:observe:send:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/init%28_%3Aobserve%3Asend%3A%29-1m32f

Initializes a view store from a store which observes changes to state.

```APIDOC
## init(_:observe:send:)

### Description
Initializes a view store from a store which observes changes to state. It is recommended to transform the store's state into the minimum data needed for the feature to optimize performance.

### Declaration
```swift
convenience init<State, Action>(
    _ store: Store<State, Action>,
    observe toViewState: @escaping (State) -> ViewState,
    send fromViewAction: @escaping (ViewAction) -> Action
)
```

### Parameters
- **store** (Store<State, Action>) - A store.
- **toViewState** ((State) -> ViewState) - A transformation of ViewState to the state that will be observed for changes.
- **fromViewAction** ((ViewAction) -> Action) - A transformation of ViewAction that describes what actions can be sent.
```

--------------------------------

### Declaration of binding(get:send:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/binding%28get%3Asend%3A%29-65xes

The function signature for deriving a binding from a view store.

```swift
func binding<Value>(
    get: @escaping (ViewState) -> Value,
    send valueToAction: @escaping (Value) -> ViewAction
) -> Binding<Value>
```

--------------------------------

### Declare alignmentGuide(_:computeValue:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/caselet/alignmentguide%28_%3Acomputevalue%3A%29-4srnl

The method signature for defining a custom horizontal alignment guide.

```swift
func alignmentGuide(
    _ g: HorizontalAlignment,
    computeValue: @escaping (ViewDimensions) -> CGFloat
) -> some View
```

--------------------------------

### init(_:onTap:destination:label:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationlinkstore/init%28_%3Aontap%3Adestination%3Alabel%3A%29

Initializes a navigation link that presents a destination view based on the state of a store.

```APIDOC
## init(_:onTap:destination:label:)

### Declaration
```swift
init(
    _ store: Store<PresentationState<State>, PresentationAction<Action>>,
    onTap: @escaping () -> Void, 
    @ViewBuilder destination: @escaping (Store<State, Action>) -> Destination, 
    @ViewBuilder label: () -> Label
) where State == DestinationState, Action == DestinationAction
```

### Description
Creates a navigation link that observes a store for presentation state. When the link is tapped, it triggers the provided `onTap` closure and navigates to the view generated by the `destination` closure.
```

--------------------------------

### init(_:state:action:id:onTap:destination:label:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationlinkstore/init%28_%3Astate%3Aaction%3Aid%3Aontap%3Adestination%3Alabel%3A%29

Initializes a navigation link store for handling presentation state. This method is deprecated.

```APIDOC
## init(_:state:action:id:onTap:destination:label:)

### Declaration
```swift
init(
    _ store: Store<PresentationState<State>, PresentationAction<Action>>,
    state toDestinationState: @escaping (State) -> DestinationState?,
    action fromDestinationAction: @escaping (DestinationAction) -> Action,
    id: DestinationState.ID,
    onTap: @escaping () -> Void, 
    @ViewBuilder destination: @escaping (Store<DestinationState, DestinationAction>) -> Destination, 
    @ViewBuilder label: () -> Label
) where DestinationState : Identifiable
```

### Availability
- iOS 13.0–16.0 (Deprecated)
- macOS 10.15–13.0 (Deprecated)
- tvOS 13.0–16.0 (Deprecated)
- watchOS 6.0–9.0 (Deprecated)
```

--------------------------------

### Declaration of alignmentGuide(_:computeValue:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/caselet/alignmentguide%28_%3Acomputevalue%3A%29-1ljxv

The method signature for defining a custom vertical alignment guide.

```swift
func alignmentGuide(
    _ g: VerticalAlignment,
    computeValue: @escaping (ViewDimensions) -> CGFloat
) -> some View
```

--------------------------------

### init(_:observe:send:content:file:line:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withviewstore/init%28_%3Aobserve%3Asend%3Acontent%3Afile%3Aline%3A%29-5d0z5

Initializes a WithViewStore structure that transforms a Store into an observable ViewStore to compute views from state.

```APIDOC
## init(_:observe:send:content:file:line:)

### Description
Initializes a structure that transforms a `Store` into an observable `ViewStore` in order to compute views from state. This allows for observing specific slices of state to prevent unnecessary view re-computations.

### Signature
```swift
init<State, Action>(
    _ store: Store<State, Action>,
    observe toViewState: @escaping (State) -> ViewState,
    send fromViewAction: @escaping (ViewAction) -> Action,
    @ViewBuilder content: @escaping (ViewStore<ViewState, ViewAction>) -> Content,
    file: StaticString = #fileID,
    line: UInt = #line
)
```

### Parameters
- **store** (Store<State, Action>) - The store to observe.
- **toViewState** ((State) -> ViewState) - A function that transforms store state into observable view state.
- **fromViewAction** ((ViewAction) -> Action) - A function that transforms view actions into store actions.
- **content** ((ViewStore<ViewState, ViewAction>) -> Content) - A function that generates content from a view store.
- **file** (StaticString) - Optional, defaults to #fileID.
- **line** (UInt) - Optional, defaults to #line.
```

--------------------------------

### Example of skipped assertion output

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore

Informational output showing state changes that were not explicitly asserted against.

```text
  App.State(
    authenticatedTab: .loggedOut(
      Login.State(
-       isLoading: false
+       isLoading: true,
        …
      )
    )
  )
```

```text
  App.State(
-   authenticatedTab: .loggedOut(…)
+   authenticatedTab: .loggedIn(
+     Profile.State(…)
+   ),
    …
  )
```

--------------------------------

### Debouncing tasks with withTaskCancellation

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withtaskcancellation%28id%3Acancelinflight%3Aoperation%3A%29

Example demonstrating how to debounce async work by setting cancelInFlight to true.

```swift
@Dependency(\.continuousClock) var clock
enum CancelID { case response }


// ...


return .run { send in
  try await withTaskCancellation(id: CancelID.response, cancelInFlight: true) {
    try await self.clock.sleep(for: .seconds(0.3))
    await send(
      .debouncedResponse(TaskResult { try await environment.request() })
    )
  }
}
```

--------------------------------

### Initialize TestStore for Navigation

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/treebasednavigation

Sets up a TestStore for the parent feature with an initial child state.

```swift
func testDismissal() {
  let store = TestStore(
    initialState: Feature.State(
      counter: CounterFeature.State(count: 3)
    )
  ) {
    CounterFeature()
  }
}
```

--------------------------------

### Combining Reducers with Scope

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/scope/init%28state%3Aaction%3Achild%3Afileid%3Aline%3A%29

Example of using Scope to combine reducers for different enum cases.

```swift
var body: some Reducer<State, Action> {
  Scope(state: /State.loggedIn, action: /Action.loggedIn) {
    LoggedIn()
  }
  Scope(state: /State.loggedOut, action: /Action.loggedOut) {
    LoggedOut()
  }
}
```

--------------------------------

### Defining Feature State

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/performance

Example of a feature state struct containing multiple child states.

```swift
struct AppFeature: Reducer {
  struct State {
    var activity: Activity.State
    var search: Search.State
    var profile: Profile.State
  }
  // ...
}
```

--------------------------------

### init(from:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/presentationstate/init%28from%3A%29

Initializes a new PresentationState instance by decoding from the provided decoder.

```APIDOC
## init(from:)

### Description
Creates a new instance by decoding from the given decoder. This method is available when the State type conforms to Decodable.

### Declaration
`init(from decoder: Decoder) throws`

### Parameters
- **decoder** (Decoder) - The decoder to read data from.
```

--------------------------------

### init(_:id:onTap:destination:label:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/navigationlinkstore/init%28_%3Aid%3Aontap%3Adestination%3Alabel%3A%29

Initializes a navigation link that presents a destination view when tapped, using a Store to manage the presentation state.

```APIDOC
## init(_:id:onTap:destination:label:)

### Declaration
```swift
init(
    _ store: Store<PresentationState<State>, PresentationAction<Action>>,
    id: State.ID,
    onTap: @escaping () -> Void, 
    @ViewBuilder destination: @escaping (Store<State, Action>) -> Destination, 
    @ViewBuilder label: () -> Label
) where State : Identifiable, State == DestinationState, Action == DestinationAction
```

### Parameters
- **store**: The store that manages the presentation state.
- **id**: The identifier for the state.
- **onTap**: A closure executed when the link is tapped.
- **destination**: A view builder that creates the destination view from a store.
- **label**: A view builder that creates the label for the navigation link.
```

--------------------------------

### init(initialState:reducer:withDependencies:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/store/init%28initialstate%3Areducer%3Awithdependencies%3A%29

Initializes a store from an initial state and a reducer, with an optional closure to override dependencies.

```APIDOC
## init(initialState:reducer:withDependencies:)

### Description
Initializes a store from an initial state and a reducer. This is the primary method for creating a store instance in the Composable Architecture.

### Declaration
```swift
convenience init<R>(
    initialState: @autoclosure () -> R.State, @ReducerBuilder<State, Action> reducer: () -> R,
    withDependencies prepareDependencies: ((inout DependencyValues) -> Void)? = nil
) where State == R.State, Action == R.Action, R : Reducer
```

### Parameters
- **initialState** (closure) - The state to start the application in.
- **reducer** (closure) - The reducer that powers the business logic of the application.
- **prepareDependencies** (closure) - Optional. A closure that can be used to override dependencies that will be accessed by the reducer.
```

--------------------------------

### Transforming a specific dependency

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/bindingreducer/transformdependency%28_%3Atransform%3A%29

Example of overriding a dependency endpoint while still calling the original implementation.

```swift
  Feature()
    .transformDependency(\.speechClient) { speechClient in
      speechClient.requestAuthorization = {
        print("requestAuthorization")
        try await speechClient.requestAuthorization()
      }
    }
```

--------------------------------

### Initialize a TestStore

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/gettingstarted

Create a TestStore to assert state changes and action sequences in a feature.

```swift
@MainActor
func testFeature() async {
  let store = TestStore(initialState: Feature.State()) {
    Feature()
  }
}
```

--------------------------------

### Testing collection mutations

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/testing

Examples of how to handle collection mutations in exhaustive versus non-exhaustive test stores.

```swift

case .removeButtonTapped:
  state.values.removeLast()
  return .none
```

```swift

await store.send(.removeButtonTapped) {
  $0.values.removeLast()
}
```

```swift

store.exhaustivity = .off
await store.send(.removeButtonTapped) {
  $0.values.removeLast()  // ❌
}
```

```swift

store.exhaustivity = .off
await store.send(.removeButtonTapped) {
  $0.values = []
}
```

```swift

store.exhaustivity = .off
await store.send(.removeButtonTapped) {
  XCTAssertEqual($0.values.count, 0)
}
```

--------------------------------

### init(Store<State, ViewAction>, observe: (State) -> ViewState, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withviewstore

Initializes a structure that transforms a Store into an observable ViewStore in order to compute views from state. This is available when ViewState conforms to Equatable and Content conforms to View.

```APIDOC
### init(Store<State, ViewAction>, observe: (State) -> ViewState, content: (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString, line: UInt)

Initializes a structure that transforms a Store into an observable ViewStore in order to compute views from state.
```

--------------------------------

### Displaying state change expectations

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/testing

Examples of how state change mismatches are represented in test failure reports.

```swift

  AppFeature.State(
    authenticatedTab: .loggedOut(
      Login.State(
-       isLoading: false
+       isLoading: true,
        …
      )
    )
  )
```

```swift

  AppFeature.State(
-   authenticatedTab: .loggedOut(…)
+   authenticatedTab: .loggedIn(
+     Profile.State(…)
+   ),
    …
  )
```

--------------------------------

### init(_:then:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/ifletstore/init%28_%3Athen%3A%29-75n86

Initializes an IfLetStore view that computes content depending on if a store of PresentationState and PresentationAction is nil or non-nil.

```APIDOC
## init(_:then:)

### Description
Initializes an `IfLetStore` view that computes content depending on if a store of `PresentationState` and `PresentationAction` is `nil` or non-`nil`.

### Declaration
`init<IfContent>(_ store: Store<PresentationState<State>, PresentationAction<Action>>, @ViewBuilder then ifContent: @escaping (Store<State, Action>) -> IfContent) where Content == IfContent?, IfContent : View`

### Parameters
- **store** (Store<PresentationState<State>, PresentationAction<Action>>) - A store of optional state.
- **ifContent** (@escaping (Store<State, Action>) -> IfContent) - A function that is given a store of non-optional state and returns a view that is visible only when the optional state is non-`nil`.
```

--------------------------------

### init(_:observe:content:file:line:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/withviewstore/init%28_%3Aobserve%3Acontent%3Afile%3Aline%3A%29-4gpoj

Initializes a structure that transforms a Store into an observable ViewStore in order to compute bindings and views from state.

```APIDOC
## init(_:observe:content:file:line:)

### Description
Initializes a structure that transforms a `Store` into an observable `ViewStore` in order to compute bindings and views from state. This is available when `ViewState` conforms to `Equatable` and `Content` conforms to `View`.

### Signature
`init<State>(_ store: Store<State, ViewAction>, observe toViewState: @escaping (BindingViewStore<State>) -> ViewState, @ViewBuilder content: @escaping (ViewStore<ViewState, ViewAction>) -> Content, file: StaticString = #fileID, line: UInt = #line) where ViewAction : BindableAction, State == ViewAction.State`

### Parameters
- **store** (Store<State, ViewAction>) - A store.
- **toViewState** ((BindingViewStore<State>) -> ViewState) - A function that transforms binding store state into observable view state. All changes to the view state will cause the `WithViewStore` to re-compute its view.
- **content** ((ViewStore<ViewState, ViewAction>) -> Content) - A function that can generate content from a view store.
- **file** (StaticString) - Optional, defaults to #fileID.
- **line** (UInt) - Optional, defaults to #line.
```

--------------------------------

### Test Failure Output for Unhandled Actions

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore

Example of the failure message generated when an action is received but not asserted.

```text
Unhandled actions: [
  [0]: Search.Action.searchResponse
]
```

--------------------------------

### Initialize a Store with dependencies

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/store/init%28initialstate%3Areducer%3Awithdependencies%3A%29

Use this initializer to define the initial state, reducer, and dependency overrides for a Store.

```swift
convenience init<R>(
    initialState: @autoclosure () -> R.State, @ReducerBuilder<State, Action> reducer: () -> R,
    withDependencies prepareDependencies: ((inout DependencyValues) -> Void)? = nil
) where State == R.State, Action == R.Action, R : Reducer
```

--------------------------------

### func help(_ textKey: LocalizedStringKey) -> some View

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/caselet/help%28_%3A%29-23maq

Sets the help text for the view using a localized string key.

```APIDOC
## func help(_ textKey: LocalizedStringKey) -> some View

### Description
Sets the help text for the view using a localized string key. This method is inherited from `View.help(_:)`.

### Parameters
- **textKey** (LocalizedStringKey) - The localized string key to use for the help text.
```

--------------------------------

### Using binding(send:) with an alert

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/binding%28send%3A%29-705m7

Example of using binding(send:) to handle an alert dismissal action.

```swift

typealias State = String
enum Action { case alertDismissed }


.alert(
  item: viewStore.binding(
    send: .alertDismissed
  )
) { title in Alert(title: Text(title)) }
```

--------------------------------

### Usage of skipInFlightEffects in a TestStore

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore/skipinflighteffects%28strict%3Afile%3Aline%3A%29

Example showing how to use skipInFlightEffects to explicitly ignore remaining effects in a test.

```swift
let store = TestStore(/* ... */)


await store.send(.buttonTapped) {
  // Assert on how state changed
}
await store.receive(.response(/* ... */)) {
  // Assert on how state changed
}


// Make it explicit you do not want to assert on how any other effects behave.
await store.skipInFlightEffects()
```

--------------------------------

### init(_:observe:send:removeDuplicates:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/init%28_%3Aobserve%3Asend%3Aremoveduplicates%3A%29-9mg12

Initializes a view store from a store which observes changes to state.

```APIDOC
## init<State, Action>(_ store: Store<State, Action>, observe toViewState: @escaping (State) -> ViewState, send fromViewAction: @escaping (ViewAction) -> Action, removeDuplicates isDuplicate: @escaping (ViewState, ViewState) -> Bool)

### Description
Initializes a view store from a store which observes changes to state. It is recommended to transform the store's state into the bare minimum of data needed for the feature to optimize performance.

### Parameters
- **store** (Store<State, Action>) - A store.
- **toViewState** ((State) -> ViewState) - A transformation of ViewState to the state that will be observed for changes.
- **fromViewAction** ((ViewAction) -> Action) - A transformation of ViewAction that describes what actions can be sent.
- **isDuplicate** ((ViewState, ViewState) -> Bool) - A function to determine when two State values are equal. When values are equal, repeat view computations are removed.
```

--------------------------------

### Initialize a TestStore

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore/init%28initialstate%3Areducer%3Awithdependencies%3Afile%3Aline%3A%29-3zio1

Use this initializer to set up a test store with a specific initial state and reducer, optionally overriding dependencies.

```swift
init<R>(
    initialState: @autoclosure () -> R.State, @ReducerBuilder<State, Action> reducer: () -> R,
    withDependencies prepareDependencies: (inout DependencyValues) -> Void = { _ in
    },
    file: StaticString = #file,
    line: UInt = #line
) where State : Equatable, State == R.State, Action == R.Action, R : Reducer
```

--------------------------------

### Scoping a Store for a Child View

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/store/scope%28state%3Aaction%3A%29-9iai9

Example of using scope to pass a narrowed store to a child view.

```swift
// Application state made from child states.
struct AppFeature: Reducer {
  struct State {
    var login: Login.State
    // ...
  }
  enum Action {
    case login(Login.Action)
    // ...
  }


// A store that runs the entire application.
let store = Store(initialState: AppFeature.State()) {
  AppFeature()
}


// Construct a login view by scoping the store
// to one that works with only login domain.
LoginView(
  store: store.scope(
    state: \.login,
    action: AppFeature.Action.login
  )
)
```

--------------------------------

### Testing a Search Feature with TestStore

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/teststore

Demonstrates initializing a TestStore with overridden dependencies and asserting on state changes and received actions.

```swift
let clock = TestClock()


let store = TestStore(initialState: Search.State()) {
  Search()
} withDependencies: {
  // Override the clock dependency with the test clock
  $0.continuousClock = clock


  // Simulate a search response with one item
  $0.apiClient.search = { _ in
    ["Composable Architecture"]
  }
)


// Change the query
await store.send(.searchFieldChanged("c") {
  // Assert that state updates accordingly
  $0.query = "c"
}


// Advance the clock by enough to get past the debounce
await clock.advance(by: 0.5)


// Assert that the expected response is received
await store.receive(.searchResponse(.success(["Composable Architecture"]))) {
  $0.results = ["Composable Architecture"]
}
```

--------------------------------

### init(_:observe:removeDuplicates:)

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/viewstore/init%28_%3Aobserve%3Aremoveduplicates%3A%29-81c6d

Initializes a ViewStore with a store, a transformation function for view state, and a predicate for removing duplicate state updates.

```APIDOC
## init(_:observe:removeDuplicates:)

### Description
Initializes a structure that transforms a `Store` into an observable `ViewStore` in order to compute bindings from state.

### Declaration
```swift
convenience init<State>(
    _ store: Store<State, ViewAction>,
    observe toViewState: @escaping (BindingViewStore<State>) -> ViewState,
    removeDuplicates isDuplicate: @escaping (ViewState, ViewState) -> Bool
) where ViewAction : BindableAction, State == ViewAction.State
```

### Parameters
- **store** (Store<State, ViewAction>) - A store.
- **toViewState** ((BindingViewStore<State>) -> ViewState) - A function that transforms binding store state into observable view state. All changes to the view state will cause the `WithViewStore` to re-compute its view.
- **isDuplicate** ((ViewState, ViewState) -> Bool) - A function to determine when two `ViewState` values are equal. When values are equal, repeat view computations are removed.
```

--------------------------------

### Implement Reducer with Effects

Source: https://pointfreeco.github.io/swift-composable-architecture/1.1.0/documentation/composablearchitecture/reducer

Example of a reducer that manages asynchronous effects, such as a timer, using cancellable identifiers.

```swift
struct Feature: Reducer {
  struct State {
    var count = 0
  }
  enum Action {
    case decrementButtonTapped
    case incrementButtonTapped
    case startTimerButtonTapped
    case stopTimerButtonTapped
    case timerTick
  }
  enum CancelID { case timer }


  func reduce(into state: inout State, action: Action) -> Effect<Action> {
    switch action {
    case .decrementButtonTapped:
      state.count -= 1
      return .none


    case .incrementButtonTapped:
      state.count += 1
      return .none


    case .startTimerButtonTapped:
      return .run { send in
        while true {
          try await Task.sleep(for: .seconds(1))
          await send(.timerTick)
        }
      }
      .cancellable(CancelID.timer)


    case .stopTimerButtonTapped:
      return .cancel(CancelID.timer)


    case .timerTick:
      state.count += 1
      return .none
    }
  }
}
```
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