Add ability to refresh modified atoms (#91)

* Add test case

* Add ability to refresh modified atoms

* Update example

* Update documentation comments

* Refactoring

* Fix tests

Author: ra1028

Examples/Packages/iOS/Sources/ExampleMovieDB/Atoms/SearchAtoms.swift

@@ -7,19 +7,15 @@ struct SearchQueryAtom: StateAtom, Hashable {
     }
 }
 
-struct SearchMoviesAtom: PublisherAtom, Hashable {
-    func publisher(context: Context) -> AnyPublisher<[Movie], Error> {
+struct SearchMoviesAtom: ThrowingTaskAtom, Hashable {
+    func value(context: Context) async throws -> [Movie] {
         let api = context.watch(APIClientAtom())
         let query = context.watch(SearchQueryAtom())
 
-        if query.isEmpty {
-            return Just([])
-                .setFailureType(to: Error.self)
-                .eraseToAnyPublisher()
+        guard !query.isEmpty else {
+            return []
         }
 
-        return api.getSearchMovies(query: query)
-            .map(\.results)
-            .eraseToAnyPublisher()
+        return try await api.getSearchMovies(query: query).results
     }
 }

Examples/Packages/iOS/Sources/ExampleMovieDB/Backend/APIClient.swift

@@ -8,7 +8,7 @@ protocol APIClientProtocol {
     func getTopRated(page: Int) async throws -> PagedResponse<Movie>
     func getUpcoming(page: Int) async throws -> PagedResponse<Movie>
     func getCredits(movieID: Int) async throws -> Credits
-    func getSearchMovies(query: String) -> Future<PagedResponse<Movie>, Error>  // Use Publisher as an example.
+    func getSearchMovies(query: String) async throws -> PagedResponse<Movie>
 }
 
 struct APIClient: APIClientProtocol {
@@ -30,7 +30,7 @@ struct APIClient: APIClientProtocol {
             imageBaseURL
             .appendingPathComponent(size.rawValue)
             .appendingPathComponent(path)
-        let request = URLRequest(url: url, cachePolicy: .returnCacheDataElseLoad, timeoutInterval: 10)
+        let request = URLRequest(url: url, cachePolicy: .returnCacheDataElseLoad, timeoutInterval: 5)
         let (data, _) = try await session.data(for: request)
         return UIImage(data: data) ?? UIImage()
     }
@@ -58,24 +58,6 @@ struct APIClient: APIClientProtocol {
     func getSearchMovies(query: String) async throws -> PagedResponse<Movie> {
         try await get(path: "search/movie", parameters: ["query": query])
     }
-
-    func getSearchMovies(query: String) -> Future<PagedResponse<Movie>, Error> {
-        Future { fulfill in
-            Task {
-                do {
-                    let response = try await get(
-                        PagedResponse<Movie>.self,
-                        path: "search/movie",
-                        parameters: ["query": query]
-                    )
-                    fulfill(.success(response))
-                }
-                catch {
-                    fulfill(.failure(error))
-                }
-            }
-        }
-    }
 }
 
 private extension APIClient {
@@ -142,9 +124,7 @@ final class MockAPIClient: APIClientProtocol {
         try creditsResponse.get()
     }
 
-    func getSearchMovies(query: String) -> Future<PagedResponse<Movie>, Error> {
-        Future { fulfill in
-            fulfill(self.searchMoviesResponse)
-        }
+    func getSearchMovies(query: String) async throws -> PagedResponse<Movie> {
+        try searchMoviesResponse.get()
     }
 }

Examples/Packages/iOS/Sources/ExampleMovieDB/Screens/SearchScreen.swift

@@ -2,7 +2,7 @@ import Atoms
 import SwiftUI
 
 struct SearchScreen: View {
-    @Watch(SearchMoviesAtom())
+    @Watch(SearchMoviesAtom().phase)
     var movies
 
     @ViewContext
@@ -36,7 +36,7 @@ struct SearchScreen: View {
         .navigationTitle("Search Results")
         .listStyle(.insetGrouped)
         .refreshable {
-            await context.refresh(SearchMoviesAtom())
+            await context.refresh(SearchMoviesAtom().phase)
         }
         .sheet(item: $selectedMovie) { movie in
             DetailScreen(movie: movie)

Examples/Packages/iOS/Tests/ExampleMovieDBTests/ExampleMovieDBTests.swift

@@ -113,33 +113,37 @@ final class ExampleMovieDBTests: XCTestCase {
         XCTAssertEqual(failurePhase.error as? URLError, error)
     }
 
-    func testSearchMoviesAtom() async {
+    func testSearchMoviesAtom() async throws {
         let apiClient = MockAPIClient()
         let atom = SearchMoviesAtom()
         let context = AtomTestContext()
         let expected = PagedResponse.stub()
-        let error = URLError(.badURL)
+        let errorError = URLError(.badURL)
 
         context.override(APIClientAtom()) { _ in apiClient }
         apiClient.searchMoviesResponse = .success(expected)
 
         context.watch(SearchQueryAtom())
 
-        let emptyQueryPhase = await context.refresh(atom)
+        let empty = try await context.refresh(atom).value
 
-        XCTAssertEqual(emptyQueryPhase.value, [])
+        XCTAssertEqual(empty, [])
 
         context[SearchQueryAtom()] = "query"
 
-        let successPhase = await context.refresh(atom)
-
-        XCTAssertEqual(successPhase.value, expected.results)
+        let success = try await context.refresh(atom).value
 
-        apiClient.searchMoviesResponse = .failure(error)
+        XCTAssertEqual(success, expected.results)
 
-        let failurePhase = await context.refresh(atom)
+        apiClient.searchMoviesResponse = .failure(errorError)
 
-        XCTAssertEqual(failurePhase.error as? URLError, error)
+        do {
+            _ = try await context.refresh(atom).value
+            XCTFail("Should throw.")
+        }
+        catch {
+            XCTAssertEqual(error as? URLError, errorError)
+        }
     }
 }
 

Sources/Atoms/Core/Loader/AsyncSequenceAtomLoader.swift

@@ -40,7 +40,7 @@ public struct AsyncSequenceAtomLoader<Node: AsyncSequenceAtom>: RefreshableAtomL
         value
     }
 
-    /// Refreshes and awaits for the passed value to be finished to yield values
+    /// Refreshes and waits for the passed value to finish outputting values
     /// and returns a final value.
     public func refresh(context: Context) async -> Value {
         let sequence = context.transaction(atom.sequence)
@@ -70,9 +70,9 @@ public struct AsyncSequenceAtomLoader<Node: AsyncSequenceAtom>: RefreshableAtomL
         }
     }
 
-    /// Refreshes and awaits for the passed value to be finished to yield values
+    /// Refreshes and waits for the passed value to finish outputting values
     /// and returns a final value.
-    public func refreshOverridden(value: Value, context: Context) async -> Value {
+    public func refresh(overridden value: Value, context: Context) async -> Value {
         value
     }
 }

Sources/Atoms/Core/Loader/AtomLoader.swift

@@ -30,12 +30,12 @@ public extension AtomLoader {
 /// A loader protocol that represents an actual implementation of the corresponding atom
 /// that provides values asynchronously.
 public protocol RefreshableAtomLoader: AtomLoader {
-    /// Refreshes and awaits until the asynchronous is finished and returns a final value.
+    /// Refreshes and waits until the asynchronous process is finished and returns a final value.
     func refresh(context: Context) async -> Value
 
-    /// Refreshes and awaits for the passed value to be finished to yield values
+    /// Refreshes and waits for the passed value to finish outputting values
     /// and returns a final value.
-    func refreshOverridden(value: Value, context: Context) async -> Value
+    func refresh(overridden value: Value, context: Context) async -> Value
 }
 
 /// A loader protocol that represents an actual implementation of the corresponding atom

Sources/Atoms/Core/Loader/ModifiedAtomLoader.swift

@@ -31,3 +31,20 @@ public struct ModifiedAtomLoader<Node: Atom, Modifier: AtomModifier>: AtomLoader
         modifier.shouldUpdate(newValue: newValue, oldValue: oldValue)
     }
 }
+
+extension ModifiedAtomLoader: RefreshableAtomLoader where Node.Loader: RefreshableAtomLoader, Modifier: RefreshableAtomModifier {
+    /// Refreshes and waits until the asynchronous process is finished and returns a final value.
+    public func refresh(context: Context) async -> Value {
+        let value = await context.transaction { context in
+            await context.refresh(atom)
+            return context.watch(atom)
+        }
+        return await modifier.refresh(modifying: value, context: context.modifierContext)
+    }
+
+    /// Refreshes and waits for the passed value to finish outputting values
+    /// and returns a final value.
+    public func refresh(overridden value: Value, context: Context) async -> Value {
+        await modifier.refresh(overridden: value, context: context.modifierContext)
+    }
+}

Sources/Atoms/Core/Loader/PublisherAtomLoader.swift

@@ -35,7 +35,7 @@ public struct PublisherAtomLoader<Node: PublisherAtom>: RefreshableAtomLoader {
         value
     }
 
-    /// Refreshes and awaits until the asynchronous is finished and returns a final value.
+    /// Refreshes and waits until the asynchronous process is finished and returns a final value.
     public func refresh(context: Context) async -> Value {
         let results = context.transaction(atom.publisher).results
         let task = Task {
@@ -59,9 +59,9 @@ public struct PublisherAtomLoader<Node: PublisherAtom>: RefreshableAtomLoader {
         }
     }
 
-    /// Refreshes and awaits for the passed value to be finished to yield values
+    /// Refreshes and waits for the passed value to finish outputting values
     /// and returns a final value.
-    public func refreshOverridden(value: Value, context: Context) async -> Value {
+    public func refresh(overridden value: Value, context: Context) async -> Value {
         value
     }
 }

Sources/Atoms/Core/Loader/TaskAtomLoader.swift

@@ -32,17 +32,17 @@ public struct TaskAtomLoader<Node: TaskAtom>: AsyncAtomLoader {
         return value
     }
 
-    /// Refreshes and awaits until the asynchronous is finished and returns a final value.
+    /// Refreshes and waits until the asynchronous process is finished and returns a final value.
     public func refresh(context: Context) async -> Value {
         let task = Task {
             await context.transaction(atom.value)
         }
-        return await refreshOverridden(value: task, context: context)
+        return await refresh(overridden: task, context: context)
     }
 
-    /// Refreshes and awaits for the passed value to be finished to yield values
+    /// Refreshes and waits for the passed value to finish outputting values
     /// and returns a final value.
-    public func refreshOverridden(value: Value, context: Context) async -> Value {
+    public func refresh(overridden value: Value, context: Context) async -> Value {
         context.addTermination(value.cancel)
 
         return await withTaskCancellationHandler {

Sources/Atoms/Core/Loader/ThrowingTaskAtomLoader.swift

@@ -32,17 +32,17 @@ public struct ThrowingTaskAtomLoader<Node: ThrowingTaskAtom>: AsyncAtomLoader {
         return value
     }
 
-    /// Refreshes and awaits until the asynchronous is finished and returns a final value.
+    /// Refreshes and waits until the asynchronous process is finished and returns a final value.
     public func refresh(context: Context) async -> Value {
         let task = Task {
             try await context.transaction(atom.value)
         }
-        return await refreshOverridden(value: task, context: context)
+        return await refresh(overridden: task, context: context)
     }
 
-    /// Refreshes and awaits for the passed value to be finished to yield values
+    /// Refreshes and waits for the passed value to finish outputting values
     /// and returns a final value.
-    public func refreshOverridden(value: Value, context: Context) async -> Value {
+    public func refresh(overridden value: Value, context: Context) async -> Value {
         context.addTermination(value.cancel)
 
         return await withTaskCancellationHandler {