Restructured the Sample app target in the Xcode project and added its unit tests target as well.

Apps/Attendi/Tests/Mocks/PreinstallingMock.swift

@@ -0,0 +1,53 @@
+import Foundation
+import Recording
+
+/// A preinstalling service that records its requests, resolves the supported locales from configurable tables, and emits events
+/// on demand.
+@MainActor
+final class PreinstallingMock: Preinstalling {
+
+    /// The stream of events the service emits while preinstalling.
+    let events: AsyncStream<PreinstallingEvent>
+
+    /// The supported equivalents the service resolves, keyed by the requested locale.
+    var equivalents: [Locale: Locale] = [:]
+
+    /// The locales the service reports as supported.
+    var localesSupported: [Locale] = []
+
+    /// The locales a preinstallation was requested for, in request order.
+    private(set) var localesPreinstalled: [Locale] = []
+
+    /// The continuation that feeds ``events``.
+    private let continuation: AsyncStream<PreinstallingEvent>.Continuation
+
+    init() {
+        (events, continuation) = AsyncStream.makeStream(of: PreinstallingEvent.self)
+    }
+
+    /// Emits the given event through ``events``.
+    ///
+    /// - Parameter event: The event to emit.
+    func emit(
+        _ event: PreinstallingEvent
+    ) {
+        continuation.yield(event)
+    }
+
+    func preinstall(
+        for locale: Locale
+    ) async {
+        localesPreinstalled.append(locale)
+    }
+
+    func supportedLocale(
+        equivalentTo locale: Locale
+    ) async -> Locale? {
+        equivalents[locale]
+    }
+
+    func supportedLocales() async -> [Locale] {
+        localesSupported
+    }
+
+}

Apps/Attendi/Tests/View Models/ContentViewModelTests.swift

@@ -0,0 +1,210 @@
+import Foundation
+import Notifying
+import Recording
+import Testing
+
+@testable import Attendi
+
+@Suite("Content view model")
+struct ContentViewModelTests {
+
+    typealias Model = ContentView.Model
+
+    // MARK: Load
+
+    @MainActor
+    @Suite("Load")
+    struct Load {
+
+        @Test
+        func `load fills the supported locales and aligns the picked locale`() async {
+            let preinstaller = PreinstallingMock()
+
+            preinstaller.localesSupported = [.dutch, .english]
+            preinstaller.equivalents = [.current: .english]
+
+            let model = Model(preinstaller: preinstaller)
+
+            await model.load()
+
+            #expect(model.locale == .english)
+            #expect(model.locales.count == 2)
+            #expect(model.locales.contains(.dutch))
+            #expect(model.locales.contains(.english))
+        }
+
+        @Test
+        func `load preinstalls the aligned locale`() async throws {
+            let preinstaller = PreinstallingMock()
+
+            preinstaller.localesSupported = [.dutch, .english]
+            preinstaller.equivalents = [.current: .english]
+
+            let model = Model(preinstaller: preinstaller)
+
+            await model.load()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(preinstaller.localesPreinstalled == [.english])
+        }
+
+    }
+
+    // MARK: Preinstall
+
+    @MainActor
+    @Suite("Preinstall")
+    struct Preinstall {
+
+        @Test
+        func `preinstalling the same locale twice runs once`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .dutch
+
+            model.preinstall()
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(preinstaller.localesPreinstalled == [.dutch])
+        }
+
+        @Test
+        func `preinstalling a newly picked locale runs again`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .dutch
+            model.preinstall()
+
+            model.locale = .english
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(preinstaller.localesPreinstalled == [.dutch, .english])
+        }
+
+    }
+
+    // MARK: Events
+
+    @MainActor
+    @Suite("Events")
+    struct Events {
+
+        @Test
+        func `a started event posts an info notification`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .dutch
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            preinstaller.emit(.started(.dutch))
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(model.notifier.notifications.count == 1)
+            #expect(model.notifier.notifications.first?.kind == .info)
+            #expect(model.notifier.notifications.first?.symbol == "arrow.down.circle")
+            #expect(model.notifier.notifications.first?.message == String(localized: .viewRecordingNotificationDownloadStarted(model.name(for: .dutch))))
+        }
+
+        @Test
+        func `a cancelled event posts a warning notification`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .dutch
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            preinstaller.emit(.cancelled(.dutch))
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(model.notifier.notifications.first?.kind == .warning)
+            #expect(model.notifier.notifications.first?.symbol == "xmark.circle")
+            #expect(model.notifier.notifications.first?.message == String(localized: .viewRecordingNotificationDownloadCancelled(model.name(for: .dutch))))
+        }
+
+        @Test
+        func `a failed event posts an error notification`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .dutch
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            preinstaller.emit(.failed(.dutch))
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(model.notifier.notifications.first?.kind == .error)
+            #expect(model.notifier.notifications.first?.symbol == "exclamationmark.triangle")
+            #expect(model.notifier.notifications.first?.message == String(localized: .viewRecordingNotificationDownloadFailed(model.name(for: .dutch))))
+        }
+
+        @Test
+        func `a cancellation of the current locale lets a re-pick retry`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .dutch
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            preinstaller.emit(.cancelled(.dutch))
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(preinstaller.localesPreinstalled == [.dutch, .dutch])
+        }
+
+        @Test
+        func `a cancellation of another locale keeps the current preinstallation`() async throws {
+            let preinstaller = PreinstallingMock()
+            let model = Model(preinstaller: preinstaller)
+
+            model.locale = .english
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            preinstaller.emit(.cancelled(.dutch))
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            model.preinstall()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(preinstaller.localesPreinstalled == [.english])
+        }
+
+    }
+
+}
+
+// MARK: - Constants
+
+private extension Locale {
+    /// A supported locale to preinstall in the tests.
+    static let dutch = Locale(identifier: "nl-NL")
+    /// Another supported locale to preinstall in the tests.
+    static let english = Locale(identifier: "en-US")
+}