NotificationSmuggler/Tests/BetterNotificationTests/BetterNotificationTests.swift

@testable import BetterNotification
import Combine
import Foundation
import Testing

struct BetterNotificationTests {
    @Test func notificationName() {
        #expect(HitchhikersNotification.notificationName.rawValue == "BetterNotification:HitchhikersNotification")
    }

    @Test func userInfoKey() {
        #expect(HitchhikersNotification.userInfoKey == "BetterNotification:HitchhikersNotification")
    }

    // MARK: - Notification extensions

    @Test func buildNotification() {
        let hitchhikers = HitchhikersNotification(answer: 42)
        let notification = Notification.better(hitchhikers)
        #expect(notification.name == HitchhikersNotification.notificationName)
        #expect(notification.userInfo?.count == 1)
        let key = HitchhikersNotification.userInfoKey
        let userInfoValue = notification.userInfo?[key] as? HitchhikersNotification
        #expect(userInfoValue == hitchhikers)
    }

    @Test func extractBetterPayload() {
        let hitchhikers = HitchhikersNotification(answer: 42)
        let notification = Notification.better(hitchhikers)
        let extracted: HitchhikersNotification? = notification.better()
        #expect(extracted == hitchhikers)
    }

    @Test func extractBetterPayloadFailsOnWrongType() {
        let imposter = Notification(
            name: HitchhikersNotification.notificationName,
            object: nil,
            userInfo: [HitchhikersNotification.userInfoKey: "imposter"]
        )
        let extracted: HitchhikersNotification? = imposter.better()
        #expect(extracted == nil)
    }

    @Test func extractBetterPayloadFailsOnMissingPayload() {
        let wrongNotification = Notification(name: HitchhikersNotification.notificationName)
        let extracted: HitchhikersNotification? = wrongNotification.better()
        #expect(extracted == nil)
    }

    // MARK: NotificationCenter extensions

    // It's important that the tests and the notification-observing tasks are not on the same actor,
    // so we make the tests @MainActor and observe notifications on another actor. Otherwise it's
    // a deadlock.

    @Test(.timeLimit(.minutes(1)))
    @MainActor func notificationCenterAsyncSequence() async throws {
        let center = NotificationCenter()
        nonisolated(unsafe) var received = false
        Task {
            for await hitchhikers in center.notifications(for: HitchhikersNotification.self) {
                #expect(hitchhikers.answer == 42)
                received = true
                break
            }
        }
        await Task.yield()

        let hitchhikers = HitchhikersNotification(answer: 42)
        center.post(.better(hitchhikers))
        while !received { await Task.yield() }
    }

    @Test(.timeLimit(.minutes(1)))
    @MainActor func notificationCenterAsyncSequenceIgnoresInvalidPayloads() async throws {
        let center = NotificationCenter()
        nonisolated(unsafe) var received = false
        let task = Task {
            for await _ in center.notifications(for: HitchhikersNotification.self) {
                received = true
            }
        }
        defer { task.cancel() }
        await Task.yield()

        // Post an invalid one that should be ignored.
        let imposter = Notification(
            name: HitchhikersNotification.notificationName,
            object: nil,
            userInfo: [HitchhikersNotification.userInfoKey: "imposter"]
        )
        center.post(imposter)

        try await Task.sleep(for: .milliseconds(10))
        #expect(!received)
    }

    @Test(.timeLimit(.minutes(1)))
    @MainActor func notificationCenterPublisher() async {
        var cancellables = Set<AnyCancellable>()
        let center = NotificationCenter()
        nonisolated(unsafe) var received = false
        center.publisher(for: HitchhikersNotification.self)
            .sink { hitchhikers in
                #expect(hitchhikers.answer == 42)
                received = true
            }.store(in: &cancellables)
        await Task.yield()

        let hitchhikers = HitchhikersNotification(answer: 42)
        center.post(.better(hitchhikers))
        while !received { await Task.yield() }
    }

    @Test(.timeLimit(.minutes(1)))
    @MainActor func notificationCenterPublisherIgnoresInvalidPayloads() async throws {
        var cancellables = Set<AnyCancellable>()
        let center = NotificationCenter()
        nonisolated(unsafe) var received = false
        center.publisher(for: HitchhikersNotification.self)
            .sink { hitchhikers in
                #expect(hitchhikers.answer == 42)
                received = true
            }.store(in: &cancellables)
        await Task.yield()

        // Post an invalid one that should be ignored.
        let imposter = Notification(
            name: HitchhikersNotification.notificationName,
            object: nil,
            userInfo: [HitchhikersNotification.userInfoKey: "imposter"]
        )
        center.post(imposter)

        try await Task.sleep(for: .milliseconds(10))
        #expect(!received)
    }
}