feat: [WIP] Add setProviderAndWait

Signed-off-by: Fabrizio Demaria <[email protected]>

Author: fabriziodemaria

Sources/OpenFeature/OpenFeatureAPI.swift

@@ -85,3 +85,22 @@ public class OpenFeatureAPI {
         .eraseToAnyPublisher()
     }
 }
+
+extension OpenFeatureAPI {
+    public func setProviderAndWait(provider: FeatureProvider) async {
+        await setProviderAndWait(provider: provider, initialContext: nil)
+    }
+
+    public func setProviderAndWait(provider: FeatureProvider, initialContext: EvaluationContext?) async {
+        var holder: [AnyCancellable] = []
+        await withCheckedContinuation { continuation in
+            let stateObserver = provider.observe().sink {
+                if $0 == .ready {
+                    continuation.resume()
+                }
+            }
+            stateObserver.store(in: &holder)
+            setProvider(provider: provider, initialContext: initialContext)
+        }
+    }
+}

Tests/OpenFeatureTests/DeveloperExperienceTests.swift

@@ -49,6 +49,29 @@ final class DeveloperExperienceTests: XCTestCase {
         XCTAssertNotNil(eventState)
     }
 
+    func testSetProviderAndWait() async {
+        let readyExpectation = XCTestExpectation(description: "Ready")
+        let errorExpectation = XCTestExpectation(description: "Error")
+        let staleExpectation = XCTestExpectation(description: "Stale")
+        let eventState = OpenFeatureAPI.shared.observe().sink { event in
+            switch event {
+            case ProviderEvent.ready:
+                readyExpectation.fulfill()
+            case ProviderEvent.error:
+                errorExpectation.fulfill()
+            case ProviderEvent.stale:
+                staleExpectation.fulfill()
+            default:
+                XCTFail("Unexpected event")
+            }
+        }
+        let provider = SlowProvider()
+        await OpenFeatureAPI.shared.setProviderAndWait(provider: provider)
+        wait(for: [readyExpectation], timeout: 0)
+
+        XCTAssertNotNil(eventState)
+    }
+
     func testClientHooks() {
         OpenFeatureAPI.shared.setProvider(provider: NoOpProvider())
         let client = OpenFeatureAPI.shared.getClient()

Tests/OpenFeatureTests/Helpers/SlowProvider.swift

@@ -0,0 +1,74 @@
+import Foundation
+import OpenFeature
+import Combine
+
+class SlowProvider: FeatureProvider {
+    public static let name = "Slow"
+    private let eventHandler = EventHandler(.stale)
+    private var holdit: AnyCancellable?
+
+    func onContextSet(oldContext: OpenFeature.EvaluationContext?, newContext: OpenFeature.EvaluationContext) {
+        eventHandler.send(.ready)
+    }
+
+    func initialize(initialContext: OpenFeature.EvaluationContext?) {
+        Task {
+            // TODO Remove the sleep in the tests
+            print(">> Sleeping")
+            try await Task.sleep(nanoseconds: 1_000_000_000)
+            print(">> Emitting Ready")
+            eventHandler.send(.ready)
+        }
+    }
+
+    var hooks: [any OpenFeature.Hook] = []
+    var metadata: OpenFeature.ProviderMetadata = DoMetadata()
+
+    func getBooleanEvaluation(key: String, defaultValue: Bool, context: EvaluationContext?) throws
+        -> ProviderEvaluation<
+            Bool
+        >
+    {
+        return ProviderEvaluation(value: !defaultValue)
+    }
+
+    func getStringEvaluation(key: String, defaultValue: String, context: EvaluationContext?) throws
+        -> ProviderEvaluation<
+            String
+        >
+    {
+        return ProviderEvaluation(value: String(defaultValue.reversed()))
+    }
+
+    func getIntegerEvaluation(key: String, defaultValue: Int64, context: EvaluationContext?) throws
+        -> ProviderEvaluation<
+            Int64
+        >
+    {
+        return ProviderEvaluation(value: defaultValue * 100)
+    }
+
+    func getDoubleEvaluation(key: String, defaultValue: Double, context: EvaluationContext?) throws
+        -> ProviderEvaluation<
+            Double
+        >
+    {
+        return ProviderEvaluation(value: defaultValue * 100)
+    }
+
+    func getObjectEvaluation(key: String, defaultValue: Value, context: EvaluationContext?) throws
+        -> ProviderEvaluation<
+            Value
+        >
+    {
+        return ProviderEvaluation(value: .null)
+    }
+
+    func observe() -> AnyPublisher<OpenFeature.ProviderEvent, Never> {
+        eventHandler.observe()
+    }
+
+    public struct DoMetadata: ProviderMetadata {
+        public var name: String? = DoSomethingProvider.name
+    }
+}